PURPOSEThree trials were conducted to define the efficacy and toxicity of interferon alfa-2a in the treatment of metastatic renal cell cancer. Univariate and multivariate analyses were performed to identify prognostic factors for survival.PATIENTS AND METHODSProspectively, 159 patients were treated with interferon alfa-2a. In the first trial, 42 patients received 50 x 10(6) U/m2 intramuscularly three times per week. In the second trial, 64 patients received gradually escalating doses of interferon alfa-2a from 3 to 36 x 10(6) U subcutaneously administered daily. The third trial was randomized; 25 patients received daily interferon alfa-2a alone and 28 were treated with daily interferon alfa-2a and 0.15 mg/kg vinblastine every 3 weeks.RESULTSThe overall response proportion was 10% (two complete and 14 partial responses). The median response duration was 12.2 months. The median survival duration was 11.4 months, with 3% of patients alive at 5 or more years. A univariate statistical analysis showed that a Ka...