Patterns of Failure and Prognostic Factors in Anal Cancer Treated with Radiotherapy

To analyze the patterns of failure and prognostic factors affecting the local control and survivals in anal cancer treated with definitive radiotherapy, and to find the most effective treatment modality.

Thirty consecutive patients, with primary cancers of the anal canal, were treated using radiotherapy, both with and without 5-FU based concurrent chemotherapy. According to the AJCC tumor stage, six patients hadwere stage I, 11 had stage II, 2 had stage IIIA, and 11 had stage IIIB tumors. The median radiation dose was 45 Gy (30-72 Gy), and with 23 patients receivinged concurrent chemotherapy (5-FU and mitomycin C in 12 patients, 5-FU and cisplatin in 7, and other drugs in 4). The Mmedian follow up period was 43 months, (ranginge, from 8- to 99 months).

Among the 1630 patients who16 were treated without surgical resection beforeprior to the radiotherapy, and a complete remission was observed in 12 patients (75%), a partial remission in 3 (19%), and a local progression in the other one patient. The Llocal failures, including persistent disease, were observed in 10 (33%), and the patients with higher T-stages (T3-4) had higher rates of local failure rates (T1-2, 21% vs. T3-4, 72%, p=0.03). Distant metastases were found in 4 patients (13%). The five year survival and disease free survival rates were 64% and 53%, respectively. The factors which affectinged the 5 year local relapse free survival were T-stage (74.9% in T1-2 vs. 28.6% in T3-4, p=0.01), and the existence of a gross tumor beforeprior to radiotherapy (84.6%, no residual vs. 45.1% with residual, p=0.03).

A Llocal recurrence was the major failure pattern in anal cancers, and the factors affecting a local failure were the T-stage and tumor volume beforeprior to radiotherapy. A Rradiation dose around 45 Gy was sufficient to control tumors of the earlier T stage tumors, but a higher dose should be considered for with more advanced lesions.