Purpose: To compare the efficacy and toxicity profiles of a combination of fluorouracil (5-FU) and recombinant human interferon alfa-2a ([IFN alpha 2a] Roferon-A; Hoffmann-LaRoche, Basel, Switzerland) versus 5-FU alone in the treatment of advanced colorectal cancer (ACC).
Patients and methods: A total of 245 previously untreated ACC patients were randomized to receive either IFN alpha 2a (9 million IU) subcutaneously (SC) three times weekly with 5-FU (750 mg/m2/d) by continuous intravenous (CIV) infusion on days 1 to 5 and then, after a 1-week hiatus, as a weekly IV bolus at the same dose (IFN/ 5-FU), or 5-FU alone at the same dose schedule (5-FU).
Results: There were no significant differences between IFN/5-FU and 5-FU alone in the overall response rate (24% v 17%, P = .2), duration of response (median, 6.4 v 8.1 months), time to response (plateau at 3 months), time to progressive disease ([PD] median, 4.8 v 4.9 months), or survival duration (median, 13.9 v 13.2 months). Toxicity profiles were not statistically different except for constitutional symptoms, which were more frequent and more severe with IFN/5-FU. More patients interrupted treatment for adverse events (AEs) with IFN/ 5-FU (34%) than with 5-FU alone (21%) (P = .03). The number of deaths (mostly unrelated to drug treatment) during the study (8%) was similar with both regimens.
Conclusion: The combination IFN/5-FU produced a response rate, response duration, and survival duration similar to that of 5-FU alone. The addition of IFN to 5-FU in the doses and schedules used in this study did not provide any further benefit over 5-FU alone and cannot be recommended for patients with metastatic ACC. This study confirms the value of large prospective randomized clinical trials to determine the clinical value of regimens that emerge from smaller single-center phase II studies.