Challenges in the management of Burkitt's lymphoma.

Burkitt's lymphoma and small noncleaved Burkitt's-like lymphoma are rare and are highly aggressive forms of non-Hodgkin's lymphoma that are characterized by dysregulation of the c-myc oncogene. Patients with human immunodeficiency virus (HIV) also appear to be at risk for developing Burkitt's lymphomas. Treatment options for Burkitt's lymphoma involve complex chemotherapy regimens that contain as many as 10 cytotoxic agents. Approximately 50%-80% of adult patients with Burkitt's lymphoma or small, noncleaved lymphoma can be cured with these intensive chemotherapy regimens, and in pediatric populations, the cure rate is even higher. However, a number of factors often compromise the outcome of patients with Burkitt's lymphoma. For instance, the high proliferation rate of Burkitt's lymphoma enhances the risk for tumor lysis syndrome, which results from metabolic imbalances, such as hyperuricemia, that occur as large numbers of malignant cells are lysed during cytotoxic chemotherapy. Standard treatment for tumor lysis syndrome includes adjustments in the chemotherapy regimen, vigorous hydration, administration of a uric acid synthesis inhibitor like allopurinol, and alkalinization. The administration of recombinant urate oxidase (rasburicase) also has been shown to provide effective prophylaxis against hyperuricemia in pediatric and adult patients with hematologic malignancies. The lifetime risk of developing central nervous system disease is 20%-30% for Burkitt's lymphoma. Consequently all chemotherapy regimens with activity in Burkitt's lymphoma utilize some form of central nervous system prophylaxis, such as systemic or intrathecal methotrexate or cytarabine. In the past, patients with HIV who developed Burkitt's lymphoma often received inadequate chemotherapy doses because of their immunosuppression. With the discovery of highly active antiretroviral therapy, the ability to treat and control Burkitt's lymphoma in patients with HIV has improved.