Randomized controlled study of natural interferon α as adjuvant treatment for stage II or III renal cell carcinoma

Background: The prophylactic effect of postoperative interferon on recurrence and distant metastasis in stage II or III renal cell carcinoma is unclear. In most studies, interferon has been administered for 6 months or less. Therefore, we performed a clinical study of the efficacy of 1-year postoperative administration of natural interferon α, which is generally used in Japan. Methods: The subjects were patients diagnosed with stage II or III renal cell carcinoma who underwent radical nephrectomy. The subjects were randomly allocated to receive an intramuscular injection of natural interferon α (3 million to 6 million units) 3 times a week for 1 year or to receive follow-up observation until recurrence or metastasis occurred. Chest and abdominal CT were performed once yearly for all patients. The primary endpoint was progression-free survival. Results: From September 2001 to August 2006, a total of 107 patients were registered, but 7 subsequently withdrew from the study. Therefore, 100 patients were included in the analysis. The primary endpoint of progression-free survival did not differ significantly between the groups that received natural interferon α or follow-up observation (p = 0.456, log-rank test). However, peak hazards of progression in the interferon group were delayed for about 6-10 months compared with the observation group. Conclusion: Progression-free survival showed no improvement after administration of natural interferon α to patients with stage II or III renal cell carcinoma for 1 year after radical nephrectomy. The peak hazards of progression might be delayed by about 6 months by interferon administration.