Phase III Study of Interferon Alfa-NL as Adjuvant Treatment for Resectable Renal Cell Carcinoma: An Eastern Cooperative Oncology Group/Intergroup Trial

Purpose: To evaluate the role of adjuvant interferon alfa after complete resection of locally extensive renal cell carcinoma. Patients and Methods: A total of 283 eligible patients with pT3–4a and/or node-positive disease were randomly assigned after radical nephrectomy and lymphadenectomy to observation or to interferon alfa-NL (Wellferon, Burroughs-Wellcome, Research Park, NC) given daily for 5 days every 3 weeks for up to 12 cycles. Patients were stratified on the basis of pathologic stage. Patients remained on treatment until documented recurrence, excessive toxicity, or patient/physician preference deemed removal appropriate. Results: At median follow-up of 10.4 years, median survival was 7.4 years in the observation arm and 5.1 year in the treatment arm (log-rank P = .09). Median recurrence-free survival was 3.0 years in the observation arm and 2.2 years in the interferon arm (P = .33). Performance status (P = .003), nodal status (N2 v N0, P < .0001), and tumor stage (P = .0002) were significant prognostic factors in multivariate analysis. A proportional hazards model examining the effects of treatment arm and time to recurrence on survival after recurrence among patients who recurred found that random assignment to interferon treatment (P = .009) and shorter time to recurrence (P < .0001) were independent predictors of shorter survival after recurrence. Although no lethal toxicities were observed, severe (grade 4) toxicities including neutropenia, myalgia, fatigue, depression, and other neurologic toxicities occurred in 11.4% of those randomly assigned to interferon treatment. Conclusion: Adjuvant treatment with interferon did not contribute to survival or relapse-free survival in this group of patients.