To investigate the potential gain of the concomitant use of radiotherapy and chemotherapy in improving local control and reducing the need for colostomy, a randomized phase III trial was performed in patients with locally advanced anal cancer.

From 1987 to 1994, 110 patients were randomized between radiotherapy alone and a combination of radiotherapy and chemotherapy. The patients had T3-4NO-3 or T1-2N1-3 anal cancer. Radiotherapy consisted of 45 Gy given in 5 weeks, with a daily dose of 1.8 Gy. After a rest period of 6 weeks, a boost of 20 or 15 Gy was given in case of partial or complete response, respectively. Surgical resection as part of the primary treatment was performed if possible in patients who had not responded 6 weeks after 45 Gy or with residual palpable disease after the completion of treatment. Chemotherapy was given during radiotherapy: 750 mg/m2 daily fluorouracil as a continuous infusion on days 1 to 5 and 29 to 33, and a single dose of mitomycin 15 mg/m2 administered on day 1.

The addition of chemotherapy to radiotherapy resulted in a significant increase in the complete remission rate from 54% for radiotherapy alone to 80% for radiotherapy and chemotherapy, and from 85% to 96%, respectively, if results are considered after surgical resections. This led to a significant improvement of locoregional control and colostomy-free interval (P = .02 and P = .002, respectively), both in favor of the combined modality treatment. The locoregional control rate improved by 18% at 5 years, while the colostomy-free rate at that time increased by 32% by the addition of chemotherapy to radiotherapy. No significant difference was found when severe side effects were considered, although anal ulcers were more frequently observed in the combined-treatment arm. The survival rate remained similar in both treatment arms. Skin ulceration, nodal involvement, and sex were the most important prognostic factors for both local control and survival. These remained significant after multivariate analysis. The improvement seen in local control by adding chemotherapy to radiotherapy also remained significant after adjusting for prognostic factors in the multivariate analysis. Event-free survival, defined as free of locoregional progression, no colostomy, and no severe side effects or death, showed significant improvement (P = .03) in favor of the combined-treatment modality. The 5-year survival rate was 56% for the whole patient group.

The concomitant use of radiotherapy and chemotherapy resulted in a significantly improved locoregional control rate and a reduction of the need for colostomy in patients with locally advanced anal cancer without a significant increase in late side effects.