Treatment of advanced diffuse histiocytic lymphoma: an analysis of prognostic variables

Sixty-five patients with Stages III and IV diffuse histiocytic lymphoma (DHL) were treated with two different and successive combination chemotherapy protocols. Twenty-seven patients were treated with the cyclophosphamide (CTX) L2 protocol, which included maintenance chemotherapy for three years. Thirty-eight patients received the NHL-3 program. Both protocols included radiotherapy (1350--4000 rad) to areas of initial bulky disease or persistent tumor, as well as central nervous system prophylaxis with intrathecal methotrexate or cytosine arabinoside in patients with bone marrow involvement. Two-year survival rates were 44 and 56%, respectively, for the CTX-L2 and NHL-3 protocols. Of the 65 patients, 59 were evaluable for response to therapy. The CTX-L2 produced a 58% total response (TR) rate, 39% complete (CR), and 19% partial (PR). The patients on NHL-3 achieved a TR rate of 82%, 33% CR, and 48% PR. The difference in TR was significant (P = 0.05), but in CR was not. Prior chemotherapy (P = 0.077) and serum lactic dehydrogenase (LDH) level above 500 U/liter (P = 0.01) significantly lessened the chances for achievement of a CR. However, sex, age, the presence of systemic symptoms, stage (III vs. IV), and prior RT were not found to be significantly related to CR rate. This analysis suggests that a high level of serum LDH characterizes a subgroup of patients with particularly aggressive DHL that requires a more intensive modality of treatment.