The significance of bone marrow involvement in non-Hodgkin's lymphoma: the Eastern Cooperative Oncology Group experience.

Data from four clinical trials conducted by the Eastern Cooperative Oncology Group (ECOG) were used to investigate the importance of bone marrow involvement as a prognostic factor in patients with non-Hodgkin's lymphoma (NHL). A total of 502 patients, 275 with nodular, poorly differentiated lymphocytic lymphoma (NLPD) and 227 with diffuse histiocytic lymphoma (DHL) or diffuse mixed-cell lymphoma (DML), were included in this analysis. Patients were separated into four categories: stage III, stage IV with bone marrow involvement (stage IV-M), stage IV without marrow involvement (stage IV-O), and stage IV with bone marrow and other organ involvement (stage IV-OM). Among the DHL and DML patients, the incidence of marrow involvement was 23%. However, stage IV-M patients had a prognosis that is similar to stage IV-O and stage IV-OM and worse than stage III patients. In contrast, the incidence of involvement with NLPD was 59% and patients with stage IV-M had a survival not different than stage III and not worse than stage IV-O and stage IV-OM. The results suggest that the current emphasis on bone marrow biopsy(s) as a routine diagnostic staging procedure for patients with NHL should be reevaluated. The necessity for this procedure in stage III patients with NLPD is not apparent from our data. One can still justify a bone marrow biopsy in stage I and II patients and can confirm the complete clinical response when all nodes have regressed in more advanced disease.