Is radiotherapy curative for stage I and II low-grade follicular lymphoma? Results of a long-term follow-up study of patients treated at Stanford University.

PURPOSE To evaluate retrospectively the results of radiotherapy for 177 patients with stage I (n = 73 [41%]) and II (n = 104 [59%]) follicular small cleaved-cell and follicular mixed small cleaved-cell and large-cell non-Hodgkin's lymphoma (NHL) treated in the Department of Radiation Oncology, Stanford University between 1961 and 1994. PATIENTS AND METHODS Histology was follicular small cleaved-cell in 101 (57%) cases and follicular mixed small cleaved-cell and large-cell in 76 (43%). Forty-five patients (25%) had staging laparotomy; 34 (19%) had extranodal involvement. All patients had received radiotherapy, either to one side of the diaphragm (involved or extended field) or to both sides (total lymphoid irradiation [TLI] or subtotal lymphoid irradiation [STLI]. Radiotherapy doses ranged from 35 to 50 Gy. RESULTS The median follow-up duration was 7.7 years. The longest follow-up duration was 31 years. Actuarial survival rates at 5, 10, 15, and 20 years were 82%, 64%, 44%, and 35%, respectively. The median survival time was 13.8 years. At 5, 10, 15, and 20 years, 55%, 44%, 40%, and 37% of patients, respectively, were relapse-free. Only five of 47 patients who reached 10 years without relapse subsequently developed recurrence. Survival and freedom from relapse (FFR) were significantly worse for older patients. Relapse rates were lower following treatment on both sides of the diaphragm or staging laparotomy. Univariate analysis showed that youth and staging laparotomy were associated with significantly better survival and that FFR was better following treatment on both sides of the diaphragm or laparotomy. CONCLUSION Radiotherapy remains the treatment of choice for early-stage low-grade follicular lymphomas. Patients who have remained free of disease for 10 years are unlikely to relapse.