ACUTE LYMPHOCYTIC LEUKEMIA
ALL results from an uncontrolled proliferation of immature cells (lymphoblasts) derived from the lymphoid stem cell. The cell of origin is the precursor to the B lymphocyte in approximately 75% of ALL cases; T-lymphocyte ALL occurs in approximately 25% of ALL cases. The BCR-ABL translocation (see earlier discussion) is found in 20% of ALL blast cells. ALL is most common in young children, with boys affected more often than girls; the peak incidence is 4 years of age. After age 15 years, ALL is relatively uncommon. Increasing age appears to be associated with dimin-ished survival (Nachman, 1999). Because of improvements in therapy for ALL, more than 80% of children survive at least5 years. Even if relapse occurs, resumption of induction therapy can often achieve a second complete remission. Moreover, BMT may be successful even after a second relapse.
Immature lymphocytes proliferate in the marrow and crowd the development of normal myeloid cells. As a result, normal hema-topoiesis is inhibited, resulting in reduced numbers of leukocytes, erythrocytes, and platelets. Leukocyte counts may be either low or high, but there is always a high proportion of immature cells. Manifestations of leukemic cell infiltration into other organs are more common with ALL than with other forms of leukemia and include pain from an enlarged liver or spleen, bone pain, and headache and vomiting (because of meningeal involvement).
The expected outcome of treatment is complete remission. Lym-phoid blast cells are typically very sensitive to corticosteroids and to vinca alkaloids; therefore, these medications are an integral part of the initial induction therapy. Because ALL frequently invades the central nervous system, prophylaxis with cranial irradiation or intrathecal chemotherapy (eg, methotrexate [Folex]) or both is an integral part of the treatment plan.
Treatment protocols for ALL tend to be complex, using a wide variety of chemotherapeutic agents. They often include a main-tenance phase, when lower doses of medications are given for up to 3 years. Despite the complexity, treatment can be provided in the outpatient setting in some circumstances until severe com-plications develop.
Infections are common, especially viral infections. The use of corticosteroids to treat ALL increases the patientâ€™s susceptibility to infection. Patients with ALL tend to have a better response to treatment than patients with AML do. BMT or PBSCT offers a chance for prolonged remission or even cure if the illness recurs after therapy.
Nursing management of the patient with acute leukemia is dis-cussed at the end of the leukemia section.