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Acute lymphoblastic leukemia (acute lympholeukemia)
Last reviewed: 07.07.2025
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Acute lymphoblastic leukemia (ALL), the most common cancer in children, also affects adults of all ages. Malignant transformation and uncontrolled proliferation of abnormally differentiated, long-lived hematopoietic progenitor cells results in circulating lymphocytes, replacement of normal bone marrow by malignant cells, and potential leukemic infiltration of the central nervous system and abdominal organs. Symptoms include fatigue, pallor, infections, bleeding tendency, and subcutaneous hemorrhage. Examination of peripheral blood smear and bone marrow is usually sufficient for diagnosis. Treatment includes combination chemotherapy to achieve remission, intrathecal chemotherapy to prevent central nervous system involvement and/or head irradiation for intracerebral leukemic infiltration, consolidation chemotherapy with or without stem cell transplantation, and maintenance therapy for 1-3 years to prevent disease relapse.
Two-thirds of all cases of acute lymphoblastic leukemia are registered in children. The peak incidence is between the ages of 2 and 10 years. Acute lymphoblastic leukemia is the most common type of cancer in children and the second cause of death in children under 15 years of age. The second peak of incidence is over 45 years of age.
[ Relapses of acute lymphoblastic leukemia
Leukemia cells may recur in the bone marrow, central nervous system, or testes. Bone marrow relapse is the most dangerous. Although second-line chemotherapy can induce repeat remission in 80-90% of children (30-40% of adults), subsequent remissions are usually short-lived. Only a small proportion of patients with late bone marrow relapse achieve long-term disease-free repeat remission or cure. In the presence of an HLA-matched sibling, stem cell transplantation offers the best chance of long-term remission or cure.
If relapse occurs in the central nervous system, treatment includes intrathecal methotrexate (with or without cytarabine and glucocorticoids) twice weekly until all symptoms have resolved. Because of the high likelihood of systemic dissemination of blast cells, most regimens include systemic reinduction chemotherapy. The role of long-term intrathecal therapy or central nervous system irradiation is unclear.
Testicular recurrence may present as a painless, firm enlargement of the testicle or may be detected by biopsy. If clinically evident unilateral testicular involvement is present, a biopsy of the other testicle should be performed. Treatment consists of radiation therapy to the affected testicles and systemic reinduction therapy, as for isolated central nervous system recurrence.
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Treatment of acute lymphoblastic leukemia
The treatment protocol for acute lymphoblastic leukemia includes 4 phases: induction of remission, prevention of central nervous system damage, consolidation or intensification (after remission) and maintenance of remission.
Several regimens emphasize early use of intensive multidrug therapy. Remission-induction regimens include daily prednisone, weekly vincristine, and the addition of an anthracycline or aspartase. Other drugs and combinations used early in treatment include cytarabine and etoposide, and cyclophosphamide. Some regimens contain medium- or high-dose intravenous methotrexate with leucovorin used to reduce toxicity. Combinations and doses of drugs may be modified based on the presence of risk factors. Allogeneic stem cell transplantation is recommended for consolidation in Ph-positive acute lymphoblastic leukemia or for a second or subsequent relapse or remission.
The meninges are an important site of involvement in acute lymphoblastic leukemia; prophylaxis and treatment may include high-dose intrathecal methotrexate, cytarabine, and glucocorticoids. Cranial nerve or whole-brain irradiation may be required; these techniques are often used in patients with high-risk central nervous system involvement (eg, high white blood cell count, high serum lactate dehydrogenase, B-cell phenotype), but their prevalence has declined in recent years.
Most regimens include maintenance therapy with methotrexate and mercaptopurine. The duration of therapy is usually 2.5-3 years, but may be shorter with more intensive regimens in the early phases and in B-cell (L3) acute lymphoblastic leukemia. In patients with a remission duration of 2.5 years, the risk of relapse after stopping therapy is less than 20%. Relapse is usually recorded within a year. Thus, if treatment can be stopped, most patients are cured.
Prognosis of acute lymphoblastic leukemia
Prognostic factors help to more accurately determine the treatment protocol and its intensity. Favorable prognostic factors are age from 3 to 7 years, white blood cell count less than 25,000/μl, FAB L1 variant of acute lymphoblastic leukemia, leukemic cell karyotype with more than 50 chromosomes and t(12;21), no central nervous system involvement at diagnosis. Unfavorable factors are leukemic cell karyotype with normal chromosome number but abnormal morphology (pseudodiploid) or presence of Philadelphia chromosome t(9;22); advanced age in adults and B-cell immunophenotype with surface or cytoplasmic immunoglobulin.
Despite risk factors, the probability of achieving primary remission in children is over 95% and in adults 70-90%. Approximately three-quarters of children have significant disease-free duration of 5 years and are considered cured. Most protocols studied select patients with poor prognosis for more intensive treatment because the increased risk of treatment failure and subsequent death outweighs the increased risk and toxicity of therapy.