Acute lymphoblastic leukemia (acute lymphocytic leukemia)

Acute lymphoblastic leukemia (acute lymphocytic leukemia), which is the most frequent oncological disease in children, also affects adults of all ages. Malignant transformation and uncontrolled proliferation of anomalously differentiated, long-lived hematopoietic progenitor cells leads to the appearance of circulating power cells, replacement of normal bone marrow with malignant cells and potential leukemia infiltration of the central nervous system and abdominal organs. Symptoms include fatigue, pallor, infection, a tendency to bleeding and subcutaneous hemorrhage. Studies of the smear of peripheral blood and bone marrow are usually sufficient to establish a diagnosis. Treatment includes combined chemotherapy to achieve remission, intrathecal chemotherapy to prevent central nervous system damage and / or head irradiation with intracerebral leukemia infiltration, consolidation chemotherapy with or without stem cell transplantation, and maintenance for 1-3 years to prevent recurrence of the disease.

Two thirds of all cases of acute lymphoblastic leukemia are recorded in children. The peak incidence falls on the age of 2 to 10 years. Acute lymphoblastic leukemia is the most common type of cancer in children and the second cause of death in children younger than 15 years. The second peak of incidence falls on age over 45 years.

[1], [2], [3], [4], [5]

Relapses of acute lymphoblastic leukemia

Leukemia cells can reappear in the bone marrow, central nervous system, or testicles. A bone resuspension is most dangerous. Although the second chemotherapy line can induce recurrence in 80-90% of children (30-40% of adults), subsequent remissions are usually short. Only a small proportion of patients with late bone marrow relapse achieve long-term remission without disease or cure. In the presence of HLA-compatible sibling, stem cell transplantation is the best chance of prolonged remission or cure.

When relapses are detected in the central nervous system, treatment involves the intrathecal administration of methotrexate (with cytarabine and glucocorticoids or without them) twice a week until all symptoms of the disease disappear. Due to the high probability of systemic spread of blast cells, most regimens include systemic re-induction chemotherapy. The role of prolonged use of intrathecal therapy or irradiation of the central nervous system is unclear.

Testicular relapse can be manifested by a painless dense enlargement of the testicle or can be detected by biopsy. In clinically obvious unilateral defeat of the testicle, a second testicle biopsy should be performed. Treatment consists of radiation therapy of the affected testicles and the use of systemic re-induction therapy, as in isolated relapse in the central nervous system.

Treatment of acute lymphoblastic leukemia

The protocol for the treatment of acute lymphoblastic leukemia includes 4 phases: induction of remission, prevention of central nervous system damage, consolidation or intensification (after remission) and maintenance of remission.

A number of regimes attach special importance to the early application of intensive multicomponent therapy. Modes of induction of remission include daily intake of prednisolone, weekly administration of vincristine with the addition of anthracycline or asparagine-nase. Other drugs and combinations used in the early stages of treatment include cytarabine and etoposide, as well as cyclophosphamide. Some regimens contain medium or high doses of methotrexate intravenously with leucovorin, used to reduce toxicity. Combinations and doses of drugs can be modified depending on the presence of risk factors. Allogeneic stem cell transplantation is recommended as consolidation with Ph-positive acute lymphoblastic leukemia or with a second or subsequent relapse or remission.

Brain shells are an important localization of lesions in acute lymphoblastic leukemia; while prevention and treatment may include intrathecal administration of high doses of methotrexate, cytarbin and glucocorticoids. It may be necessary to irradiate the cranial nerves or the entire brain, these methods are often used in patients with a high risk of damage to the central nervous system (eg, high leukocyte count, high serum lactate-hydrogenase, B-cell phenotype), but in recent years their prevalence decreased.

Most regimens include maintenance therapy with methotrexate and mercaptopurine. The duration of therapy is usually 2.5-3 years, but may be shorter in regimens that are more intense in the early phases and with B-cell (L3) acute lymphoblastic leukemias. In patients with a remission duration of 2.5 years, the risk of recurrence after discontinuation of therapy is less than 20%. Usually relapse is registered within a year. Thus, if it is possible to stop treatment, 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 the age from 3 to 7 years, the level of leukocytes is less than 25 000 / μL, the FAB L1 variant of acute lymphoblastic leukemia, the karyotype of leukemia cells with the presence of more than 50 chromosomes and t (12, 21), the absence of central nervous system damage at the time of diagnosis . Adverse factors are karyotype of leukemic cells with a normal number of chromosomes, but anomalous morphology (pseudo-diploid) or the presence of the Philadelphia chromosome t (9; 22); elderly age in adults and B-cell immunophenotype with superficial or cytoplasmic immunoglobulin.

Despite the risk factors, the probability of achieving primary remission in children is more than 95% and in adults 70-90%. About 3/4 of the children have a significant duration without disease for 5 years, and they are considered cured. In most of the protocols under study, patients with poor prognosis are selected for more intensive treatment, because the increased risk of treatment failure and subsequent death outweighs the increased risk and toxicity of therapy.