Relapse in Burkitt's lymphoma.

Of 109 patients with histologically confirmed Burkitt's lymphoma who completed a course of chemotherapy, 86 (79%) achieved complete remission. Forty-five (52%) of patients with initial complete remission relapsed with tumour over an observation period ranging from 2 years to over 5 years. Relapse was more common in patients who initially presented with abdominal or central nervous system (CNS) involvement than in patients who presented with localized facial tumours (p less than 0.01). Anatomical distribution of tumour on relapse differed from that at presentation. Facial bones were much less frequently involved on relapse; on the other hand, the CNS, cranial nerves, orbits and skin were frequent sites of disease on relapse. CNS involvement occurred in 42% (19/45) of patients at the first relapse and in 73% (11/15) of patients with multiple relapses. Prognosis in these patients was poor. Two relapse types were clinically identifiable. Early relapse (remission duration less than 12 weeks) was associated with frequent involvement of the CNS, drug resistance and a generally unfavourable outcome. Patients with late relapse (remission duration greater than 12 weeks) responded much better to secondary treatment. Possible pathogenic mechanisms underlying these two relapse types are discussed.