hematology and oncology
Acute Lymphoblastic Leukemia (ALL)
Introduction
Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer; it also strikes adults of all ages. Malignant transformation and uncontrolled proliferation of an abnormally differentiated, long-lived hematopoietic progenitor cell results in a high circulating number of blasts, replacement of normal marrow by malignant cells, and the potential for leukemic infiltration of the central nervous system (CNS) and testes. Symptoms include fatigue, pallor, infection, bone pain, CNS symptoms (eg, headache), easy bruising, and bleeding. Examination of peripheral blood smear and bone marrow is usually diagnostic. Treatment typically includes combination chemotherapy to achieve remission, intrathecal and systemic chemotherapy and/or corticosteroids for CNS prophylaxis, and sometimes cerebral irradiation for intracerebral leukemic infiltration, consolidation chemotherapy with or without stem cell transplantation, and maintenance chemotherapy for up to 3 years to avoid relapse. (See also Overview of Leukemia .) TheAmerican Cancer Societyestimates that in the United States in 2023 there will be over 6500 new cases of acute lymphoblastic leukemia (ALL) and almost 1400 deaths will have occurred. Sixty percent of all ALL cases occur in children, with a peak incidence at age 2 to 5 years; a second peak occurs after age 50. ALL is the most common cancer in children, and represents about 75% of leukemias among children < 15 years of age. The risk declines slowly until the mid-20s and then begins to rise again slowly after age 50. ALL accounts for about 20% of adult acute leukemias. The average lifetime risk of ALL in both sexes is about 0.1% (1 in 1000 Americans). Hispanic populations have a higher incidence of ALL than other racial or ethnic populations due in part to polymorphisms in theARID5Bgene. 