Intergroup RTOG 98–11: A phase III randomized study of 5-fluorouracil (5-FU), mitomycin, and radiotherapy versus 5-fluorouracil, cisplatin and radiotherapy in carcinoma of the anal canal

Abstract

4009 Background: An ∼65% 5-year disease-free-survival (DFS) rate from 5-FU/mitomycin/radiation for anal carcinoma needs improvement. Methods: A phase III randomized trial compared 5-FU (1,000mg/m2 days 1–4 and 29–32) plus mitomycin (10mg/m2 days 1 and 29) and radiation (45 to 59 Gy) (Arm A) to 5-FU (1,000mg/m2 days 1–4, 29–32, 57–60 and 85–88) plus cisplatin (75mg/m2 on days 1, 29, 57 and 85) and radiation (45 to 59 Gy; start day=57) (Arm B) in anal carcinoma patients. Stratification included gender, clinical N status and tumor diameter. Primary endpoint was DFS. Statistical power was 80% with two-sided test to detect 10% DFS increase for Arm B. Results: Of 682 patients accrued, 598 were analyzable. Most unanalyzed patients’ data are early. Patient characteristics were balanced. Median age was 55 years, women predominated (69%), 27.5% had >5 cm tumor diameter and 26% had clinically N+ cancer. Preliminary 5-year estimated DFS was 56% for Arm A and 48% for Arm B (p=0.28) and 5-year estimated overall survival was 69% for both arms (p=0.24). Men(p=0.04), clinically N+ cancer (p<0.0001) and tumor diameter >5 cm (p=0.005) independently prognosticated DFS in a multivariate analysis. 5-year colostomy rate was 10% for Arm A and 20% for arm B(p=0.12). Grade 3/4 toxicity rates: non-hematologic=76% for Arm A and 75% for Arm B but hematologic=67% for Arm A and 47% for Arm B(p=0.0004). Conclusions: In Intergroup-98–11, induction 5-FU/cisplatin followed by 5-FU/cisplatin/radiation failed to improve DFS compared to the standard treatment, 5-FU/mitomycin/radiation. Supported by RTOG U10 CA21661, CCOP U10 CA37422, Stat U10 CA32115. No significant financial relationships to disclose.