The patterns of failure in patients with pathological stage I and II diffuse histiocytic lymphoma treated with radiation therapy alone.

Radiation therapy was used to treat 36 patients with pathological Stage I and II diffuse histiocytic lymphoma at The University of Chicago Hospitals from 1970 to 1986. Twenty-two patients had pathological Stage I and 14 had pathological Stage II diffuse histiocytic lymphoma. The patients were treated with a median tumor dose of 50 Gy (range of 40-60 Gy). Therapy consisted of extended field radiation therapy in 27 patients (extended mantle or total nodal irradiation) and involved field irradiation in nine patients. The 10-year actuarial relapse-free survival for pathological Stage I and pathological Stage II patients was 91% and 35%, respectively (median follow-up of 7 years). None of the 22 pathological Stage I patients had bulky mediastinal or abdominal disease. Of the 22 pathological Stage I patients, one failed in an unirradiated contiguous lymph node and one relapsed with disseminated disease. Of the 14 pathological Stage II patients, two patients with bulky disease failed in field, one patient failed in a contiguous node, three patients failed within the abdomen, and three patients failed with disseminated disease. To better evaluate the efficacy of staging laparotomy, we analyzed the patterns of failure of 17 clinical Stage I and II diffuse histiocytic lymphoma patients. Four of these patients failed in field (three in sites of bulky disease), and five patients relapsed in the abdomen (three with disseminated disease). Salvage treatment with multiagent chemotherapy resulted in second complete responses in seven of ten patients; however, all but one have recurred and are dead of disease. Radiation therapy may be used as the sole treatment in patients with pathological Stage I diffuse histiocytic lymphoma without bulky disease. Patients with pathological Stage II diffuse histiocytic lymphoma and clinically staged patients have a higher incidence of dissemination and relapse within the abdomen. A benefit resulting from the administration of extended field irradiation was not revealed by this study.