Concurrent chemoradiotherapy for squamous cell carcinoma of the anus using a shrinking field radiotherapy technique without a boost

Chemoradiotherapy (CRT) is now widely accepted as the primary treatment modality for squamous cell cancer of the anus. While randomised trials have clearly shown CRT to be more effective than radiotherapy alone, there remains uncertainty over the optimal integration of chemotherapy and radiation. We describe a series of 50 patients treated by a site specialist gastrointestinal nonsurgical oncologist with CRT at a single UK centre. Chemotherapy comprised mitomycin C (MMC) (day 1) and 5-fluorouracil (5-FU) (days 1–4, and 29–32), concurrent with 50 Gy in 25 fractions radiation, using a two-phase shrinking field technique. A radiation boost was not planned. At a median follow-up of 48 months, 11 (22%) of the patients have failed locally, of which three have been surgically salvaged. Nine (18%) have died of anal cancer. These results are comparable with those from large randomised studies, and suggest that a two-phase shrinking field radiotherapy technique with no boost, concurrent with MMC/5-FU chemotherapy, is an effective regimen for this disease. The CRT regimen described here provides the basis for the ‘control arm’ of the current UK-randomised CRT trial in anal cancer (ACT2).