5-Fluorouracil/leucovorin/interferon alpha-2a in patients with advanced colorectal cancer. Effects of maintenance therapy on remission duration.

Background. A Phase II study of combination treatment with 5-fluorouracil (5-FU), leucovorin (LV), and interferon alpha-2a (IFN) in patients with previously untreated metastatic colorectal cancer was previously reported by the authors. Therapy was on an outpatient basis and consisted of LV 60 mg orally every 8 hours days 1-3, IFN 18 × 106 IU subcutaneously days 1-3, and bolus 5-FU 750 mg/m2 intravenously days 2-3. Treatment was repeated every 14 days, until a maximum of 8 courses was administered. A response rate of 54% [95% confidence interval (CI), 34-72%] was observed. However, remission duration after cessation of therapy was short, with a median duration of 5 months (range, 2 to 13+ months). Methods. Subsequent to the above study, patients on this induction treatment who achieved remission received maintenance therapy: the above described 3-day regimen every 6 weeks until progression, for a maximum of 2 years. Results. Fifty-three patients were enrolled in the induction regimen and 18 out of 29 patients who achieved remission received maintenance treatment. In 50 assessable patients 3 complete recoveries and 26 partial recoveries were observed for a response rate of 58% (CI, 43-72%). Median remission duration of patients receiving maintenance therapy was 9.4 months (CI, 8.4-10.3 months) compared with 4.7 months (CI, 3.2-6.2 months) for patients without maintenance therapy. Median overall survival of all patients was 16.6 months. Toxicity of maintenance therapy was confined to WHO grade 2. Conclusions. The high response rate of this 5-FU/LV/IFN regimen holds true in a larger group of patients. The group that received maintenance treatment had a remission duration of just over 9 months, the maintenance regimen added little toxicity. Cancer 1995;75:1072–6.