Three cytotoxic drugs combined with pelvic radiation and as maintenance chemotherapy for patients with squamous cell carcinoma of the anus (SCCA): long-term follow-up of a phase II pilot study using 5-fluorouracil, mitomycin C and cisplatin.

Purpose: Phase III trials in the 1990s for squamous cell carcinoma of the anus (SCCA) demonstrated 5-fluorouracil (5FU) and mitomycinC (MMC) chemoradiation (CRT) improved outcome compared to radiation (RT) alone, but local recurrence remained significant. This prospective pilot study intensified treatment by integrating 3 cytotoxic drugs into CRT and maintenance chemotherapy.

Methods: CRT comprised 5-FU 1000 mg/m(2) days 1-4,29-32, MMC 10 mg/m(2) day 1 and Cisplatin (CDDP) 60 mg/m(2) days1 and 29, with 45 Gy in 25 daily fractions, followed by a 15 Gy boost. Maintenance chemotherapy started 4-8 weeks later, three courses repeated every 21 days, using 5-FU/CDDP doses above, with MMC reduced to 7 mg/m(2) and administered with the first and third cycles.

Results: In CRT only 14/19 (74%) patients received protocol-defined chemotherapy doses in week 5. Compliance to maintenance chemotherapy was poor. 15/19 started cycle 1, 13 started cycle 2 and 11 cycle 3. 17/19 experienced G3-G5 toxicity (16 Grade 3/4 and one Grade 5). 16/19 patients (84%) remain alive and disease-free - median follow-up 79 months (34-115).

Conclusions: Despite favourable results, the significant toxicity and low compliance of the three-drug CRT regimen used, deemed it unsuitable for testing in a phase III trial. A two-drug maintenance regimen was explored in the ACT II trial.