Acute lymphocytic leukemia
Highlights
Acute Lymphocytic Leukemia (ALL)
There are four major types of leukemia. ALL is the most common type of leukemia diagnosed in children, and the least common type diagnosed in adults. About 5,200 people are diagnosed with ALL each year. Children account for two-thirds of these cases. In general, children with ALL have a better prognosis than adults. Most children with ALL can be cured of this cancer.
Symptoms and Diagnosis
Symptoms of ALL include fatigue, pale skin, recurrent infections, bone pain, bruising, and small red spots under the skin. Doctors use various tests, including blood counts and bone marrow biopsies, to diagnose ALL.
Treatment
ALL is treated with chemotherapy and, sometimes, radiation. Children receive different types of chemotherapy regimens than adults. Patients with advanced cancer that has not responded to these treatments may need a stem cell transplant.
Infection Prevention
Both chemotherapy and transplantation increase the risk for infection. Patients must take serious precautions to avoid exposure to germs. Ways to prevent infection include:
- Practice good hygiene including regular handwashing and dental care (brushing, flossing)
- Avoid crowds, especially during cold and flu season
- Eat only well-cooked foods (no raw fruits or vegetables)
- Boil tap water before drinking it
- Do not keep fresh flowers or plants in your house as they may carry mold
Introduction
The word leukemia literally means "white blood" and is used to describe a variety of cancers that begin in the blood-forming cells of the bone marrow.
White blood cells (leukocytes) evolve from immature cells referred to as blasts. Malignancy in these blasts is the source of leukemias, which generally progresses as follows:
- Normally, blasts constitute 5% or less of healthy bone marrow. In leukemia, however, these blasts remain abnormally immature and multiply continuously, eventually constituting between 30 - 100% of the bone marrow.
- Eventually these malignant blast cells fill up the bone marrow and prevent production of healthy red cells, platelets, and mature white cells (leukocytes).
They spill out of the marrow into the bloodstream and lymph system and can travel to the brain and spinal cord (the central nervous system). As the number of normal cells decline, dangerous symptoms develop, which, if untreated, become lethal.
Leukemias are divided into two major types:
- Acute (which progresses quickly with many immature white cells)
- Chronic (which progresses more slowly and has more mature white cells)
Some blasts are called lymphoblasts (which become mature cells called lymphocytes) and others are called myeloblasts (which mature to myeloid cells). Acute leukemias are in turn subdivided into two classifications according to whether the malignant blasts are lymphocytes or myeloid:
- Acute lymphocytic leukemia (ALL), which is the subject of this report
- Acute myeloid leukemia (AML), which is not covered in this report
Acute lymphocytic leukemia (ALL) is also known as acute lymphoid leukemia or acute lymphoblastic leukemia. The majority of childhood leukemias are of the ALL type. Malignancies in this disease can arise either in T-cell or B-cell lymphocytes.
- T cell ALL is diagnosed in 15% of children and adults with ALL.
- About 85% of ALL cases are of the B-cell lymphocyte lineage (often referred to as "early" or "pre" B-cell lineage).
Blood Cell Lines
In adults, blood cells are produced by the bone marrow, the spongy material filling the body's bones. The bone marrow produces two blood cell groups, myeloid and lymphoid.
Myeloid Cell Line. The myeloid cell line includes the following:
- Immature cells called erythrocytes that later develop into red blood cells
- Blood clotting cells (platelets)
- Some white blood cells, including macrophages (which act as scavengers for foreign particles), eosinophils (which trigger allergies and also defend against parasites), and neutrophils (the main defenders against bacterial infections)
Lymphoid Cell Line. The lymphoid cell line includes the lymphocytes, which are the body's primary infection fighters. Among other vital functions, certain lymphocytes are responsible for producing antibodies, factors that can target and attack specific foreign substances (antigens).
Lymphocytes develop in the thymus gland or bone marrow and are therefore categorized as either B cells (bone marrow-derived cells) or T cells (thymus gland-derived cells).
Lymphocytes and the Lymph System
Understanding how acute lymphocytic leukemia (ALL) arises requires knowledge of lymphocytic development and function:
- B cells develop and mature in their final form (known as differentiation) in the bone marrow.
- T cells also start out in the bone marrow but differentiate and mature in the thymus gland, located beneath the breastbone. This small gland is active mostly in the fetal stage through the first 10 years of life, after which it atrophies (shrinks).
- B-cell and T-cell lymphocytes leave these organs through the bloodstream, which eventually branches out into the tiny blood vessels called capillaries.
- Once they leave the capillaries, some lymphocytes migrate into the surrounding tissues. Some of these lymphocytes (along with fluid, proteins, and other substances) then enter the lymphatic vessels.
- Lymphatic vessels begin as tiny, blind-ended tubes and lead to larger lymphatic ducts and branches. They drain into two ducts in the neck, where the fluid re-enters the bloodstream.
- Along the way, the fluid passes through lymph nodes, which are oval structures composed of lymph vessels, connective tissue, and white blood cells. Here, the lymphocytes are either filtered out or are added to the contents of the node.
Symptoms
The symptoms of ALL may be difficult to recognize. ALL usually begins abruptly and intensely, but in some cases symptoms may develop slowly. They may be present one day, and absent the next, particularly in children. Symptoms develop when:
- There are not enough healthy mature white blood cells (leukocytes) to mount a defense against infection.
- There are not enough healthy platelets to prevent bleeding.
- The depleted oxygen-bearing red blood cells can't provide enough oxygen to organs.
Symptoms include:
- Fatigue
- Paleness -- patients may have poor coloring from anemia caused by insufficient red blood cells
- Recurrent minor infections
- Fevers
- Bone pain
- Bruising -- may result from only slight injury
- Poor healing of minor cuts
- Uncontrolled bleeding -- bleeding events increase as the bone marrow fails to produce enough platelets to make a normal blood clot, a condition called thrombocytopenia.
- Small, red spots on the skin (petechiae)
- Vision changes (rare)
Causes
Between 1973 - 1990, the number of acute lymphocytic leukemia cases in children under age 15 rose by 27%. The causes of the disease are not known, but experts believe that ALL develops from a combination of genetic, biologic, and environmental factors.
Advances in genetic technologies have allowed identification of a number of mutations associated with ALL. Missing or defective genes that suppress tumors are responsible for some of these cases. Identifying specific genetic allows doctors to determine how aggressive a specific case is and eventually could provide targets for developing highly specific treatments.
Translocations. Up to 65% of leukemias contain genetic rearrangements, called translocations, in which some of the genetic material (genes) on a chromosome may be altered, or shuffled, between a pair of chromosomes.
- The most common genetic injury in ALL is t(12;21), which means a translocation with a genetic shift occurred between chromosome 12 and 21. This translocation is also referred to as TEL-AML1 fusion. It occurs in about 20% of patients with ALL. Researchers believe that this translocation may occur during fetal development in some patients.
- About 20% of adults and about 5% of children with ALL have a genetic abnormality called the Philadelphia (Ph) chromosome [t(9;22)].
- Another important chromosome translocation is t(4;11) involving the MLL gene, also called HRX or ALL-1.
Ikaros. A defective gene known as Ikaros, which regulates lymphocyte development, may play a major role in childhood ALL.
MTHFR. Methylenetetrahydrofolate reductase (MTHFR) is an enzyme involved in folate metabolism. Children with certain variations in the gene for MTHRF have a reduced risk of developing ALL. Variations in the MTHRF gene may also influence response to antifolate chemotherapy.
Risk Factors
ALL in Children. ALL is the most common type of cancer diagnosed in children. ALL accounts for about 75% of cases of childhood leukemia. Each year, about 2,400 American children and adolescents are diagnosed with ALL. ALL can strike children of all ages, but is most likely to occur when children are 2 - 3 years of age.
ALL in Adults. ALL is the least common type of leukemia among adults. About 1 in 3 cases of ALL occur in adults.
Caucasian and Hispanic children have a much higher risk for ALL than African-American children.
Certain inherited disorders can increase the risk for leukemia. For example, children with Down syndrome have a 20-times greater risk of developing ALL than the general population. Other rare genetic disorders associated with increased risk include Bloom syndrome, Fanconi's anemia, ataxia-telangiectasia, neurofibromatosis, Shwachman syndrome, IgA deficiency, and congenital X-linked agammaglobulinemia.
Previous cancer treatment with high doses of radiation or chemotherapy can increase the risk for developing ALL. Prenatal exposure to x-rays also appears to increase risk in children. Lower levels of radiation (living near power lines, video screen emissions, small appliances, cell phones) are unlikely to pose any cancer risk.
Diagnosis
Laboratory tests provide the basis for diagnosing ALL.
Flow cytometry uses light to count blood cells in a stream of fluid. It is an important tool used to diagnose leukemia, determine its progress, and tell if any disease remains after treatment. It can also determine the components and structural features of individual cells. Flow cytometry can process thousands of cells in seconds.
A complete blood cell count (CBC) is the first step in diagnosing ALL. However, blood tests do not always detect leukemia. About 10% of patients with ALL have a normal blood cell count. A CBC may show various findings, including:
- Presence of circulatory leukemic blast cells (may miss the cells on occasion)
- Presence and severity of anemia
- Count of a variety of blood cell types (a high white blood cell count indicates a more severe disease)
Click the icon to see an illustrated series detailing a complete blood cell count test.
If blood test results are abnormal or the doctor suspects leukemia despite normal cell counts, a bone marrow aspiration and biopsy are the next steps. These are very common and safe procedures. However, because this test can produce considerable anxiety, particularly in children, parents may want to ask the doctor if sedation is appropriate for their child.
- A local anesthetic is given.
- A needle is inserted into the bone, usually the rear hipbone. There may be brief pressure or pain. A small amount of marrow is withdrawn. Marrow looks like blood.
- A larger needle is then inserted into the same place and pushed down to the bone. The health professional will wiggle the needle from side to side to loosen a larger specimen for the biopsy. The patient will feel some pressure.
- The sample is then taken to the lab to be analyzed. All the results are completed within a couple of days.
Click the icon to see an image of bone marrow removal.
Normal bone marrow contains 5% or less of blast cells (the immature cells that ordinarily develop into healthy blood cells). In leukemia, abnormal blasts constitute between 30 - 100% of the marrow.
If bone marrow examination confirms ALL, a spinal tap may be performed, which uses a needle inserted into the spinal canal. The patient feels some pressure and usually must lie flat for about an hour afterward to prevent severe headache. This can be difficult, particularly for children, so parents should plan reading or other quiet activities that will divert the child during that time. Parents should also be certain that the professional administering this test is highly experienced.
Click the icon to see an image of a spinal tap.
A sample of cerebrospinal fluid with leukemia cells is a sign that the disease has spread to the central nervous system. In most cases of childhood ALL, leukemia cells are not found in the cerebrospinal fluid.
Once a diagnosis of leukemia has been made, further tests are performed to check:
- Whether the cells are myeloid or lymphocytic
- Stage of maturity of the ALL B cell
- Specific markers, or immunologic features, on the surface of the cancer cell
- The genetic makeup of the cells ( cytogenetics)
- The physical characteristics of the cells ( morphology)
First, the doctors must determine the cell of origin. In other words, they want to determine if the cell is myeloid or lymphocytic. One method is to measure an enzyme called terminal deoxynucleotidyl transferase (TdT).
- About 95% of all ALL types (except the subtype B cell) have elevated TdT.
- Only about 20% of cases of acute myeloid leukemia (AML) express TdT, however, so its use in determining the cell line is limited.
The stage of maturity of the leukemic B cell helps determine prognosis. There are three stages:
- Early precursor-B. About 80% of patients with ALL have the early precursor-B subtype, which is the least mature. It also offers the best prognosis.
- Precursor-B. This is the intermediate stage.
- B cell. This is the mature cell and ALL in this stage is identical to Burkitt's non-Hodgkin's lymphoma. It is therefore treated differently from other ALL cases.
A series of tests are used to determine the immunologic pattern of the leukemia cell (how it can be expected to interact with the immune system).
On the surface of malignant ALL cells are markers for certain antigens (molecules that set off a targeted attack by the immune system using antibodies). Such antigens are proving to be very helpful in predicting outcome.
Important antigens associated with ALL include:
- CD10, more frequently referred to as cALLa (common ALL antigen). This antigen occurs in about half of all ALL cases and in about 80% of ALL B-precursor patients. It is associated with a good prognosis.
- CD95 (associated with a good prognosis)
- CR19
- DR
The surfaces of T-cell ALL cancer cells express several antigens as well. For example, the presence of one of these, CD2, suggests a favorable prognosis.
Genetic tests are useful for a number of important criteria:
- Diagnosing a specific ALL subtype
- Designing appropriate treatment
- Deciding prognosis
- Monitoring patients throughout treatment and beyond
Cytogenetics is a technique that researchers use to determine specific genetic abnormalities, which are found in nearly 65% of all leukemias. Detecting these genetic defects is helpful in making a full diagnosis of ALL and in planning the most appropriate therapy. Specific technologies called microarray chips are capable of checking up to 48,000 different genes in a single test, which holds promise for assessing prognosis and developing very targeted therapies in the future. Research on DNA microarray analysis continues to reveal different prognostic subgroups of ALL. As the precision, logistics, and cost effectiveness of DNA microarray assays improve, they may be used more commonly in the clinical setting.
MTHFR Variants. Methylenetetrahydrofolate reductase (MTHFR) is an enzyme involved in folate metabolism. Variations in the MTHRF gene may also influence response to antifolate chemotherapy. A 2004 study showed that patients with one of two specific variations of the MTHFR gene had a lower probability of survival following treatment with methotrexate.
Translocations. Genetic translocations (swapping of genes on chromosomes) may affect outlook. Examples include:
- Patients with the t(12;21) genetic translocation (also referred to as TEL-AML1 fusion) have an excellent prognosis.
- Patients who carry the defective gene called ETV6 often respond well to chemotherapy.
- The t(4;11), sometimes referred to as MLL, is the most common translocation in children under age 1 year. Unfortunately, anyone with t(4;11) has a poor outlook. One study suggested that this genetic variant may actually be a unique leukemia and require treatments that differ from standard ALL.
- The Philadelphia translocation t(9;22) also indicates a poor outlook. It represents about 20% of adult cases and about only 5% of childhood cases.
- The t(1;19) location occurs in about 5% of ALL childhood cases and requires aggressive treatment.
Ploidy. Ploidy refers to the number of chromosomes. Additional copies (hyperdiploidy) or absence of copies (hypodiploidy) of chromosomes affect prognosis. For example, in children hyperdiploidy is associated with a more favorable outcome and hypodiploidy with a poorer outcome. (Hypodiploidy occurs in only 1% of children with ALL.)
The morphology of a cell includes its physical characteristics, such as shape and structure. To determine the morphology of the leukemia cells, samples of the bone marrow are taken and particular contents of the cells are stained with a dye. They are then examined under a microscope.
Acute lymphocytic leukemia cells are grouped, according to the French-American-British (FAB) classification system, into three ALL morphologic types. (It should be noted that this system is subjective and is now used to complement other diagnostic tests mentioned above):
- L1 cells. These are small blasts with scant amounts of cytoplasm (the substance in a cell between its membrane and nucleus). L1 cells usually contain a round nucleus and there is little variation among them. L1 represents the most common ALL morphology and offers the best prognosis. It occurs in about 85% of children and 30% of adults with ALL.
- L2 cells. These cells are larger than L1 and have more abundant cytoplasm. They vary significantly among each other and have an irregularly shaped nucleus. L2 morphology conveys a poorer prognosis than L1, although the two cells' types are treated similarly. Subtype L2 is the most common morphologic type in ALL adults; 64% of adults with ALL have this subtype compared with only 15% of children.
- L3 cells. These are uncommon. They resemble another malignancy called Burkitt's lymphoma, and their treatments are now the same.
Assays that test for cancerous cells are improving, allowing doctors to detect smaller and smaller amounts of hidden disease. For example, flow cytometry assays can detect 0.01% leukemic cells, and PCR assays can detect 0.001% leukemic cells. A new concept called minimal residual disease (MRD) is becoming an important prognostic factor in ALL. A more precise measure of disease response, MRD may soon replace existing measures such as "complete response" and "partial response" when assessing the effectiveness of ALL treatment. Ongoing studies of MRD in ALL may help identify patients in remission who are at risk of relapse. In addition, early therapeutic intervention based on the presence of MRD may improve outcome and prolong survival.
Using the results of the tests described above, patients are classified into low-, average-, and high-risk groups. This information allows the doctor to diagnosis the type of leukemia and plan the best treatment. Each classification requires unique therapies.
Doctors attempt to make a prognosis and determine an optimal treatment plan by assessing all the cell characteristics plus the white blood cell count. As examples:
- Patients who have an L1 or L2 morphology, a white blood cell count of less than 15,000 mm3, a t(12;21) genetic translocation, and a cALLa-positive antigen marker have an excellent outlook.
- On the other hand, patients who have an L2 morphology, a white blood cell count greater than 30,000 mm3, and who lack the cALLa marker have a poorer prognosis and require more aggressive treatment
Outlook
Acute lymphocytic leukemia is responsible for about 1,400 deaths a year in the U.S., and it can progress quickly if untreated. However, ALL is one of the most curable cancers and survival rates are now at an all-time high. People who have Philadelphia chromosome-positive ALL tend to have a poorer prognosis, although new treatments are helping many of these patients achieve remission.
Outlook in Children with ALL. More than 95% of children with ALL attain remission.
Certain children are at higher risk for a poor outcome than others:
- Infants and children age 10 years and older tend to have a poorer outcome than young children (ages 1 - 9 years).
- Some studies indicate a better prognosis for girls than boys. This may be partly due to boys’ risks for testicular cancer.
- Survival rates for African-American and Hispanic children are lower than Caucasian and Asian children, but this may be due to poorer access to treatment.
Responding well to early treatment is a good sign regardless of the risk category. Other positive predictors include:
- Less than 5% of cells being blasts after 7 - 14 days of treatment
- Less than 1,000 blasts per microliter on peripheral smear after 7 days
Outlook in Adults with ALL. Adults tend to have a more severe condition than children, even if they are carrying the same ALL genes. Still, 60 - 80% of adults with ALL can expect to achieve full remission with standard treatments, and 35 - 40% survive beyond 2 years with aggressive treatments. Younger adults with ALL have better long-term survival rates than older adults with the disease.
Treatment
The aim of initial treatment is to get rid of the leukemia cells in the body (achieve complete remission) and have 5% of lower levels of blasts in the bone marrow.
There are typically four treatment stages for the average-risk patient with ALL:
- Induction therapy in order to achieve a first remission
- Central nervous system prophylaxis (preventive treatment), usually given along with induction therapy
- Consolidation, intensive therapy to prevent relapse after remission has been achieved
- Maintenance treatment, lower intensity therapy given for several years to prevent relapse after remission
The following are specific treatments used for ALL:
- Chemotherapy is the primary treatment for each stage.
- Radiation to the brain and spinal cord is also administered in some cases.
- A bone marrow transplant is often recommended for relapsed ALL or in cases that cannot be induced into remission (refractory disease). It is also sometimes considered after remission is achieved for certain high-risk ALL types. The timing of bone marrow transplantation can be controversial, particularly after a first remission, although it has produced excellent long-term survival rates in appropriate patients.
- New drugs known as biological therapies are also being used.
Drugs Used to Prevent Infections During Treatment. Half of all patients with ALL develop fever in the early stages, especially if patients also have low levels of the white blood cells called neutrophils (a condition called neutropenia).
Neutropenia, common in ALL, is a significant risk factor for serious infection. Doctors are increasingly concerned about fungal infections, which are becoming more common in these patients, particularly after transplant procedures.
- Antibiotics and Antifungal Medications. The use and timing of antibiotics and antifungal medications depend on the particular organisms and severity of the infection. In some cases of neutropenia, patients may need preventive antibiotics.
- Granulocyte Colony-Stimulating Factor. Granulocyte colony-stimulating factor (lenograstim, filgrastim) is often given to patients who receive chemotherapy in order to stimulate the growth of infection-fighting white blood cells. This helps prevent neutropenia.
Intravenous Fluids. Patients may also need to receive intravenous fluids and be treated for fluid imbalances, which can cause abnormal levels of sodium, potassium, calcium, and uric acid. Such treatments might include sodium bicarbonate, allopurinol, and aluminum hydroxide or calcium carbonate.
Transfusions. Red blood cell or platelet transfusions may be needed. (Patients who may need allogeneic transplantations should not receive transfusions from potential donors.)
Home Management
A parent should call the doctor if the child has any symptoms that are out of the ordinary, including (but not limited) to:
- Any fever of 101°F or higher
- Any signs of a flu or cold
- Shortness of breath
- Severe diarrhea
- Blood in the urine or stools
- Trouble urinating
Tracking Neutrophils. Parents should track their child's absolute neutrophil count. This measurement for the amount of white blood cells is an important gauge of a child's ability to fight infection.
- Counts over 1,000 usually provide sufficient protection so that children can engage in normal activities, including school and other functions where they are exposed to other children.
- If the count is between 500 - 1,000, the child should avoid large groups.
- If it falls between 200 - 500, the child should stay at home and should see only healthy visitors who have washed their hands vigorously.
- Neutrophil counts below 200 indicate that the child is at high risk for infection and should have no visitors.
Maintaining Strict Hygiene. Children with ALL and anyone exposed to them, not only friends and family members but also doctors and nurses, should maintain strict hygiene:
- Frequent hand washing with antibacterial soap is particularly essential.
- Everyone should wash their hands before and after meals, after being outside, before preparing food, and after going to the bathroom.
- When visiting the doctor, a parent should ask about a side entrance or areas where the patient will not be exposed to other sick children.
Vaccinations. Studies now suggest that young survivors of leukemia have an increased risk for measles, mumps, and rubella (MMR), even if they have been previously vaccinated. Children may need reimmunization. Siblings of patients with ALL who require polio vaccinations should be given the killed virus (IPV), not the live polio vaccination (OPV).
- Use a soft toothbrush when counts are low to prevent gum bleeding.
- Avoid common pain relievers known as nonsteroidal anti-inflammatory drugs (NSAIDs). They increase the risk for bleeding and include aspirin, ibuprofen (Motrin IB, Advil, Nuprin, Rufen), naproxen (Aleve), and ketoprofen (Actron, Orudis KT).
Some of the drugs used for leukemia cause extreme sun sensitivity. Children should wear sunblock and be covered with sun-protective clothing when going outside to avoid sunburn, which can cause skin infection.
Treatment to Achieve Remission
The aim of induction therapy, the first treatment phase, is to reduce the number of leukemia cells to undetectable levels. The general guidelines for induction therapy are as follows:
- Patients are given intensive chemotherapy that uses powerful multi-drug regimens. (Infants require special regimens not discussed here.)
- For both children and adults, some of these therapies are administered orally, others intravenously.
- Hospitalization is usually necessary at some point to help prevent infection and to administer blood products. However, much of this therapy can be given on an outpatient basis.
- After the first cycle of induction, bone marrow tests are done to determine if the patient is in remission.
- Another bone marrow test is sometimes done about a week later to confirm the first results.
- A bone marrow transplant is considered for patients who do not respond at all to induction treatment.
Both children and adults typically start with a 3-drug regimen. Imatinib (Gleevec) or dasatanib (Sprycel) may be added for patients with Philadelphia chromosome-positive ALL.
For children, the standard drugs are:
- Vincristine (Oncovin), a vinca alkaloid drug
- Prednisone or dexamethasone. These drugs are corticosteroids. Dexamethasone may be more effective than prednisone, but it increases the risk for infections and other serious side effects.
- Asparaginase. Generally provided as pegaspargase (Oncaspar) in place of L-asparaginase (Elspar) for treating newly diagnosed ALL in children. With pegaspargase, patients need only 3 injections over a 20-week period instead of the 21 injections required for L-asparaginase.
For adults, the standard drugs are:
- Vincristine
- Prednisone
- Anthracycline drug, such as such as doxorubicin, daunorubicin, or epirubicin. Some adult chemotherapy regimens also add on an asparaginase drug or cyclophosphamide (Cytoxan).
The induction chemotherapy described above does not penetrate the blood-brain barrier sufficiently to destroy leukemic cells in the brain. CNS prophylaxis is critical for preventing disease that has spread to the brain, spine, and testes (called sanctuary disease sites). Although only 3% of children with ALL have evidence of leukemia in the central nervous system (CNS) at the time of diagnosis, leukemia will spread to this region in 50 - 70% of children who don't receive preventive (prophylactic) treatment. The brain is one of the first sites for relapsing leukemia.
For children, CNS prophylaxis uses intrathecal chemotherapy, in which a drug is injected directly into the spinal fluid. Intrathecal chemotherapy is given with methotrexate alone or a combination of methotrexate, cytarabine, and hydrocortisone.
Some high-risk children also receive radiation to the skull (cranial irradiation), radiation to the spine, or both at the same time. This combination can be very toxic and can cause later learning problems. It is generally used only in children who have evidence of the disease in the central nervous system at the time of diagnosis. Later complications can include learning and neurologic problems. Using lower-dose units of radiation, however, may significantly reduce the risk for mental impairment. Cranial radiation is also associated with increased risks for stroke and secondary cancers.
Adult CNS prophylaxis is performed in one of three ways:
- Cranial radiation plus intrathecal chemotherapy with methotrexate
- High-dose systemic infusion of methotrexate plus intrathecal methotrexate without cranial radiation
- Intrathecal methotrexate chemotherapy alone
Survival in acute leukemia depends on complete remission. Although not always clear-cut, remission is indicated by the following:
- All signs and symptoms of leukemia disappear.
- There are no abnormal cells in the blood, bone marrow, and cerebrospinal fluid.
- The percentage of blast cells in the bone marrow is less than 5%.
- Blood platelet count returns to normal.
Induction can produce extremely rapid results, and the faster the time to remission the better the outlook:
- A complete remission usually occurs within the first 4 weeks. Patients who show low disease levels within 7 - 14 days have an excellent outlook, particularly if they have favorable genetic factors, and may need less-intensive treatments afterward.
- Patients with high disease levels at 14 days or who require more than 4 weeks to achieve remission are at higher risk for relapse and most likely need more aggressive treatment.
Side effects and complications of any chemotherapeutic regimen and radiation therapy are common, are more severe with higher doses, and increase over the course of treatment. Administering drugs for shorter duration can sometimes reduce toxicities without affecting the drugs' cancer-killing effects.
Common Side Effects. Typical side effects include:
- Nausea and vomiting. Drugs known as serotonin antagonists, such as ondansetron (Zofran) or granisteron (Kyril), can relieve these side effects in nearly all patients given moderate drugs, and most patients who take more powerful drugs. In one study, nearly all patients who took a combination of dexamethasone (a steroid) in combination with ondansetron within 24 hours of chemotherapy experienced either a significant or complete reduction in nausea and vomiting.
- Diarrhea
- Hair loss
- Weight loss
- Depression
Serious Side Effects. Serious side effects can also occur and may vary depending on the specific drugs used.
Infection from suppression of the immune system or from severe drops in white blood cells is a common and serious side effect. Patients should make all efforts to prevent infection. The patient at high risk for infection may need very potent antibiotics and antifungal medications as well as granulocyte colony-stimulating factors or G-CSF (lenograstim, filgrastim) to stimulate the growth of infection-fighting white blood cells. Patients should make all efforts to minimize exposure to bacteria and viruses. (See “Infection Prevention” in the Transplant section of this report.)
Other serious side effects include:
- Liver and kidney damage
- Immediate and short-term risks of radiation therapy may include seizures, stroke, and paralysis
- Very high levels of uric acid in the blood, which can damage the kidneys
- Very high levels of calcium in the blood
- Abnormal blood clotting
- Allergic reaction
- Low blood sugar (hypoglycemia) -- a rare complication in young, thin children who are taking purine analogues such as mercaptopurine and thioguanine
- Suppression of adrenal glands in children who take short-term, high-dose corticosteroids such as prednisolone
Long-Term Complications.
- Fatigue is very common after chemotherapy and can be significant and long-lasting.
- Combinations of intrathecal chemotherapy plus brain radiation in children can cause some serious complications, including seizures and problems in learning and concentration. Methotrexate is particularly toxic. (The effects of intrathecal chemotherapy alone on mental functioning, however, did not seem significant.) Seizures can often be treated successfully with anti-epilepsy medications.
- Delayed puberty. The effects of treatment in the brain can affect regions that regulate reproductive hormones, which may affect fertility later on. Chemotherapy, cranial radiation, or both can impair fertility in male and female patients. Cranial radiation can also result in impaired growth.
- Bone loss can occur after chemotherapy, particularly with corticosteroids and after bone marrow transplantation. Drugs are available, particularly bisphosphonates, which may help reduce this risk.
- Pancreatic beta-cell damage. A 2004 study reported that children who have been off treatment for at least 1 year have a higher risk of impaired insulin response. This suggests that chemotherapy-induced beta cell damage persists after therapy has been stopped.
- Heart damage. Some of the treatments increase risk factors for future heart disease, including unhealthy cholesterol levels and high blood pressure. Anthracyclines (doxorubicin, daunorubicin, epirubicin) have been associated with later development of heart failure. Lower doses used for many ALL children may not pose a high risk to the heart. Some anthracyclines (DaunoXome, Myocet, Doxil) now come in tiny protective capsules that may reduce toxic effects. Patients with ALL should be sure to maintain a healthy lifestyle and be regularly monitored for heart risks to help reduce these effects.
- Stroke. Survivors of childhood leukemia are at increased risk of later stroke, especially if they received treatment with cranial radiation.
- Obesity. Children treated for ALL are at higher risk for obesity, possibly because the treatments trigger an earlier than normal occurrence in childhood weight gain. Corticosteroid drugs used in treatments also increase appetite, which contributes to the problem.
- Central nervous system. Radiation and intrathecal MTX therapy may be associated with an increased risk of mood disturbances (such as depression) among adult survivors of childhood ALL. Patients with depression may benefit from psychosocial support. Cranial radiation and drugs used in chemotherapy, especially specific corticosteroids and spinal injection treatments, may also impair mental functioning and cause neurologic problems, such as movement problems.
- Infections. Some children may be more vulnerable to infections after completing chemotherapy, although the immune system tends to improve over time. Patients who have had a bone marrow transplantation or lung damage from the treatments may be particularly vulnerable. Studies suggest that young survivors of leukemia have an increased risk for measles, mumps, and rubella (MMR), even if they have been previously vaccinated. Children, then, may need reimmunization.
- Secondary Cancers. Studies indicate that survivors of childhood ALL are at increased risk of later developing other types of cancers, including brain and spinal cord tumors, basal cell skin carcinoma, and myeloid (bone marrow) malignancies. Radiation and older types of chemotherapy are mainly responsible for this risk. Newer types of ALL treatment may be less likely to cause secondary cancers.
Treatment During Remission
Consolidation and maintenance therapies follow induction and first remission. The goal of consolidation and maintenance therapies is to prevent a relapse. The specific treatment choices and degree of aggressiveness after induction therapy depend on a number of factors, particularly the risk factors for relapse.
Consolidation therapy is additional treatment that is administered after induction therapy and before maintenance therapy. This is an intense regimen that is designed to prevent the high relapse rates that occur with induction therapy alone. (The benefits of this therapy are clearer in children than in older adults, who may just be given maintenance.)
Consolidation therapy usually continues for about 6 months and uses 1 - 6 courses of chemotherapy, depending on risk factors for relapse.
Examples of consolidation regimens for children at standard risk:
- A limited number of courses of intermediate- or high-dose methotrexate, one of the oldest drugs used for leukemia.
- An anthracycline drug, such as daunorubicin (Cerubidine), used for reinduction followed by cyclophosphamide (Cytoxan, Neosar) 3 months after remission. These are very powerful drugs, but when used in this way toxicity is limited.
- Extended use of an asparaginase drug.
More intense regimens are used for children at high-risk for relapse.
Instead of chemotherapy alone as consolidation therapy, some high-risk patients in first remission who are unlikely to be cured by standard chemotherapy alone may undergo allogeneic stem cell or autologous stem cell bone marrow transplant after the intensive chemotherapy regimens. Many adult patients may fall into this category. Studies on high-risk children have been conflicting about the value of transplants during a first remission.
- Allogeneic transplantation is an option when a well-matched donor is available. Although this treatment can be effective in keeping the leukemia away, significant complications -- such as graft versus host disease, blood clots, liver problems, and lung damage -- can occur and may be a cause of death even without a return of cancer.
- Autologous stem cell bone marrow transplant (using the patient's own bone marrow cells) seems to be helpful also and may be as effective as allogeneic transplantation.
The last phase of treatment is maintenance, or continuation therapy:
- Maintenance therapy typically uses weekly administration of methotrexate (usually in oral form) and daily doses of mercaptopurine. (Mercaptopurine should be given in the evening.)
- Treatment continues for 2 - 3 years for most children with ALL (with the exception of those with mature B-cell leukemia). It is not yet clear if prolonged maintenance therapy benefits adults with ALL.
- If children were not given CNS prophylaxis before, it may be given now.
- Vincristine and a corticosteroid drug (generally dexamethasone) are often added to standard maintenance therapy, although some studies indicate that they do not provide additional benefit.
A maintenance regimen is usually less toxic and easier to tolerate than induction and consolidation. Some studies, however, indicate that overall survival could further be improved with more-aggressive maintenance therapies, including:
- Vincristine and a corticosteroid added to the standard maintenance regimen
- Longer term low-dose maintenance
- Intense regimens similar to induction (called reinduction)
Maintenance is typically ongoing until complete remission has lasted 2 - 3 years.
Investigation is ongoing to determine the best drugs and schedules to use. For example, doctors have debated whether thioguanine is a better choice than mercaptopurine (a 2006 study recommended that mercaptopurine remain the standard thiopurine drug for treating childhood ALL). Researchers are also trying to pinpoint patients who would best benefit from aggressive maintenance treatments.
The following are factors that increase the risk for relapse after initial treatments:
- Microscopic evidence of leukemia after 20 weeks of therapy (minimal disease)
- Age over 30
- A high white blood cell count at the time of diagnosis
- Disease that has spread beyond the bone marrow to other organs
- Certain genetic abnormalities, such as the presence of the Philadelphia chromosome or MLL gene translocations
- Patients with high disease levels after 7 - 14 days of induction therapy
- The need for 4 or more weeks of induction chemotherapy in order to achieve a first complete remission
Patients with one or more of these risk factors may be candidates for bone marrow transplantation once they are in first remission.
Treatment After Relapse
Between 50 - 70% of children and 40 - 50% of adults who achieve complete remission after initial therapy but then suffer a relapse may be able to go into a second complete remission.
Treatment for relapse after a first remission may be standard chemotherapy or experimental drugs, or more aggressive treatments such as stem cell transplants.
The decision depends on a number of factors:
- Children who relapse 3 or more years after achieving a first complete remission have an excellent chance for a second remission without aggressive treatments.
- Those who relapse fewer than 6 months following initial treatment, especially while on chemotherapy, have about a 20% chance of long-term freedom from disease. In such cases, remission is possible following another course of standard chemotherapy but the duration of remission is usually fewer than 6 months.
Treatment decisions also rely on prior treatments and where the relapse has occurred. Relapse can occur in the bone marrow, central nervous system, or sanctuary disease sites (brain, spine, or testicles). The incidence of relapse in sanctuary sites is about 10%.
Candidates for transplantation include:
- Patients who relapse following initial remission with standard chemotherapy.
- High-risk patients in first remission who are unlikely to be cured by standard chemotherapy alone. Many adult patients may fall into this category. Studies on high-risk children have been conflicting about the value of transplants during a first remission.
- Patients who fail to achieve a complete remission during initial chemotherapy.
Transplantation procedures do not appear to offer any additional advantages for patients at low or standard risk.
Many different drugs are used to treat ALL relapses. These drugs include vincristine, asparaginase, anthracyclines (doxorubicin, daunorubicin), cyclophosphamide, cytarabine (ara-C), and epipodophyllotoxins (etoposide, teniposide). Corticosteroids, such as prednisone or dexamethasone, may also be used.
In 2004, the Food and Drug Administration (FDA) approved clofarabine (Clolar) for treatment of relapsed or refractory ALL in children. This drug was the first new leukemia treatment approved specifically for young patients in more than a decade. In 2005, nelarabine (Arranon) was approved to treat adults and children with relapsed or refractory T-cell acute lymphocytic leukemia (T-ALL). In 2006, the FDA approved imatinib (Gleevec) for treating patients with Philadelphia chromosome-positive ALL that has not responded to or has returned after treatment. Also in 2006, the FDA approved dasatinib (Sprycel) for patients who are not helped by imatinib.
Tyrosine kinase inhibitors. Tyrosine kinase is a growth-stimulating protein. Tyrosine kinase inhibitor drugs block the cell signals that trigger cancer growth. Several tyrosine kinase inhibitors, including imatinib (Gleevec) and dastinib (Sprycel), have recently been approved for treating Philadelphia chromosome-positive ALL. In 2006 clinical trials, Nilotinib (AMN-107) produced excellent results in patients with Philadelphia chromosome positive ALL who are resistant to imatinib.
Monoclonal antibodies (MAbs). Used alone or in combination with chemotherapy, MAbs target specific antigens on ALL blast cells. Although MAbs have been studied primarily in the treatment of B-cell non-Hodgkin's lymphoma, drugs demonstrating benefit in preliminary trials of ALL include anti-CD20 (rituximab) and anti-CD22 (epratuzumab). Alemtuzumab (MabCampath) is also showing promise in treating relapsed or refractory T-ALL. More studies are needed to determine the best MAb regimens in ALL.
In order to administer high-dose chemotherapy for advanced cancer cases, stem cell transplantation procedures may be used. These procedures are based on removal and replacement of stem cells, which are produced in the bone marrow. Stem cells are the early forms for all blood cells in the body (including red, white, and immune cells). Cancer treatments harm growing cells as well as cancer cells, and so the healthy stem cells must be replaced by transplanting them from the donor into the patient.
Sources of Cells. Stem cells must first be collected either from:
- Bone marrow (bone marrow transplantation)
- Blood (peripheral blood stem cell transplantation). Evidence suggests that peripheral blood stem cell transplantation may be the superior approach. Studies report survival rates of 45% in bone marrow transplant patients compared to 65 - 70% in stem cell transplant patients, with benefits being significant in those with more severe disease.
- Fetal umbilical cord or placentas. This procedure uses donor cells but has a lower risk for immune system rejection of the cells than with a standard donor transplant. It takes longer to restore blood cells with this process, however, so at this time its use is limited to children and sometimes adults with low weight. (Some studies indicate success for adults with normal weights.)
Donor or Patient Cells. The sources of marrow or blood cells can be taken from the patient or a donor:
- If the bone marrow or stem cells are taken from a donor, the transplant is referred to as allogeneic. Allogeneic transplants from genetically matched sibling donors offer the best results in ALL. With new techniques, donor bone marrow from unrelated but immunologically similar donors is proving to work as well as those from matched siblings. This approach is still reserved for patients in second remission or beyond. A 2006 study indicated that allogeneic transplant is also a good treatment option for patients with Philadelphia chromosome-positive ALL who are resistant to imatinib (Gleevec).
- If the marrow or blood cells used are the patient's own, the transplant is called autologous. Autologous transplants in patients with ALL are generally not beneficial, since there is some danger that the cells used may contain tumor cells and the cancer can regrow. Treatment advances that reduce this risk, however, may make autologous transplantation feasible in patients without family donors.
- The donor is usually given a drug called granulocyte colony-stimulating factor, or G-CSF (filgrastim, lenograstim) to stimulate stem cell growth.
- The donor (or patient in an autologous procedure) then undergoes apheresis. With this process, the blood is withdrawn from one of the patient's veins and passed through a machine that filters out the white cells and platelets, which contain the stem cells. The blood is returned through another vein. The entire procedure takes 3 - 4 hours but needs to be repeated several times.
- The stem cells are then frozen.
- The patient is given high-dose chemotherapy with or without radiation -- a treatment known as conditioning. The point is to inactivate the immune system and to kill any residual malignant cells. Drugs used are typically cyclophosphamide, carmustine, and etoposide. Alternative conditioning includes radiation with drugs.
- A few days after treatment, the patient is rescued using the stored stem cells, which are administered through a vein. This may take several hours. Patients may experience fever, chills, hives, shortness of breath, or a fall in blood pressure during the procedure.
- The patient is kept in a protected environment to minimize infection, and the patient usually needs blood cell replacement and nutritional support.
Two- to 5-year survival rates after transplantation plus chemotherapy range from 40 - 80%. Certain patients with the Philadelphia chromosome, which carries a poor prognosis, may achieve significant success with an allogeneic bone marrow transplant from a closely matched related donor.
Common side effects include nausea, vomiting, fatigue, mouth sores, and loss of appetite.
Blood stem cell transplantation itself is fairly dangerous and has a small risk for death. When it was first used, transplantation procedures had 10 - 25% morality rates. Now, mortality rates are below 5%. Potentially serious complications include:
Infection resulting from a weakened immune system is the most common side effect. Because the stem cell procedure is done more swiftly, the risk period is shorter than with bone marrow transplantation. The risk for infection is most critical during the first 6 weeks following the transplant, but it takes 6 - 12 months post-transplant for a patient’s immune system to fully recover. Immune systems of patients with graft-versus-host disease can take even longer to function normally
Many patients develop severe herpes zoster virus infections (shingles) or have a recurrence of herpes simplex virus infections (cold sores and genital herpes). Pneumonia, cytomegalovirus, aspergillus (a type of fungus), and Pneumocystis carinii (a protozoan) are among the most important life-threatening infections.
It is very important that patients take precautions to avoid infections. Guidelines for post-transplant infection prevention include:
- Discuss with your doctor what vaccinations you need and when you should get them.
- Avoid crowds, especially during cold and flu season.
- Be diligent about hand washing and make sure that visitors wash their hands.
- Avoid eating raw fruits and vegetables -- food should be well cooked. Do not eat foods purchased at salad bars or buffets. In the first few months after the transplant, be sure to eat protein-rich foods to help restore muscle mass and repair cell damage caused by chemotherapy and radiation.
- Boil tap water before drinking it.
- Dental hygiene is very important, including daily brushing and flossing. Schedule regular visits with your dentist.
- Do not sleep with pets. Avoid contact with pets’ excrement.
- Avoid fresh flowers and plants as they may carry mold. Do not garden.
- Swimming may increase exposure to infection. If you swim, do not submerge your face in water. Do not use hot tubs.
- Report to your doctor any symptoms of fever, chills, cough, difficulty breathing, rash or changes in skin, and severe diarrhea or vomiting. Fever is one of the first signs of infection. Some of these symptoms can also indicate graft-versus-host disease.
- Report to your ophthalmologist any signs of eye discharge or changes in vision. Patients who undergo radiation or who are on long-term steroid therapy have an increased risk for cataracts.
Graft-versus-host disease (GVHD) is a serious attack by the patient's immune system triggered by the donated new marrow in allogeneic transplants. To reduce the risk for GVHD, doctors remove some immune T cells from the donor’s stem cells before the transplant. Researchers are investigating new techniques to refine this process of T cell depletion.
Acute GVHD occurs in 30 - 50% of allogeneic transplants, usually within 25 days. Its severity ranges from very mild symptoms to a life-threatening condition (more often in older patients). The first sign of acute GVHD is a rash, which typically develops on the palms of hands and soles of feet and can then spread to the rest of the body. Other symptoms may include nausea, vomiting, stomach cramps, diarrhea, loss of appetite and jaundice (yellowing of skin and eyes). To prevent acute GVHD, doctors give patients immune-suppressing drugs such as steroids, methotrexate, cyclosporine, tacrolimus, and monoclonal antibodies.
Chronic GVHD can develop 70 - 400 days after the allogeneic transplant. Initial symptoms include those of acute GVHD. Skin, eyes, and mouth can become dry and irritated, and mouth sores may develop. Chronic GVHD can also sometimes affect the esophagus, gastrointestinal tract and liver. Bacterial infections and chronic low-grade fever are common. Chronic GVHD is treated with similar medicines as acute GVHD.
Too much sun exposure can trigger GVHD. Be sure to always wear sunscreen (SPF 15 or higher) on areas of the skin that are exposed to the sun. Stay in the shade when you go outside.
Other potentially serious complications include:
- Bleeding because of reduced platelets (highest risk within the first 4 weeks); blood transfusions may be required
- Infertility
- Organ complications to the liver, heart, kidney, or lungs
- Failure of the transplant
- Muscle problems, including stiffness, cramps, and joint pain
- Frequent urination and bladder control problems
- Older patients should be screened for osteoporosis (thinning of bones) and hypothyroidism (underactive thyroid)
Resources
- www.leukemia-lymphoma.org -- Leukemia and Lymphoma Society
- www.cancer.org -- American Cancer Society
- www.cancer.gov -- National Cancer Institute
- www.bmtnews.org -- Blood and Marrow Transplant Information Network
- www.asco.org -- American Society of Clinical Oncology
- www.plwc.org -- People Living with Cancer
- www.aspho.org -- American Society of Pediatric Hematology/Oncology
- www.candlelighters.org -- Candlelighters Childhood Cancer Foundation
- www.clf4kids.com -- Childhood Leukemia Foundation
References
Belson M, Kingsley B, Holmes A. Risk factors for acute leukemia in children: a review. Environ Health Perspect. 2007 Jan;115(1):138-45. Campbell LK, Scaduto M, Sharp W, et al. A meta-analysis of the neurocognitive sequelae of treatment for childhood acute lymphocytic leukemia. Pediatr Blood Cancer. 2007 Jul;49(1):65-73.
Hijiya N, Hudson MM, Lensing S, et al. Cumulative incidence of secondary neoplasms as a first event after childhood acute lymphoblastic leukemia. JAMA. 2007 Mar 21;297(11):1207-15.
Ribera JM, Ortega JJ, Oriol A, et al. Comparison of intensive chemotherapy, allogeneic, or autologous stem-cell transplantation as postremission treatment for children with very high risk acute lymphoblastic leukemia: PETHEMA ALL-93 Trial. J Clin Oncol. 2007 Jan 1;25(1):16-24.
Waber DP, Turek J, Catania L, et al. Neuropsychological outcomes from a randomized trial of triple intrathecal chemotherapy compared with 18 Gy cranial radiation as CNS treatment in acute lymphoblastic leukemia: findings from Dana-Farber Cancer Institute ALL Consortium Protocol 95-01. J Clin Oncol. 2007 Nov 1;25(31):4914-21.
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
