Patterns of treatment failure in Burkitt's lymphoma.

We have studied patterns of treatment failure in 49 evaluable children with Burkitt's lymphoma (BL) who received chemotherapy at different levels of intensity of cyclophosphamide, vincristine, methotrexate (MTX) or cytosine arabinoside, with or without high-dose dexamethasone, combined with intrathecal MTX. We observed 8 (16%) non-responders (NR), 8 (16%) partial (PR) and 33 (67%) complete responders (CR). PR + NR were all dead by the 10th observation month, while the survival graph plateaued at 70% around the 10th month for CR. We projected that 44% of all evaluable patients would experience prolonged survival beyond the 12th observation month. Three and 5 CR relapsed systemically and in the CNS respectively. Thus 11, 10 and 3 of 26 treatment failures were directly attributable to resistance to chemotherapy, sanctuary effect of the CNS or both respectively. Late complications of paraplegia were responsible for the other two failures. We conclude that drug resistance of BL cells and pharmacological sanctuary effect of the CNS are the major problems in the chemotherapeutic eradication of BL.