Genital invasion or perigenital spread may pose a risk of marginal misses for Intensity Modulated Radiotherapy (IMRT) in anal cancer
The optimal treatment for squamous and cloacogenic tumors of the anorectum is controversial. Radical surgery, limited surgery, and radiotherapy (XRT) are all potentially curative. This study was undertaken to determine which patients are candidates for each type of treatment and which would benefit from combined treatment. The records of 192 patients treated at this institution between 1954 and 1979 with the diagnosis of squamous or cloacogenic carcinoma of the anorectum were retrospectively reviewed. A subgroup of 132 patients undergoing abdominal perineal resection (APR) was analyzed to determine prognostic factors for these tumors. No survival difference was observed between the two histologic types (P = 0.51). Prognostic variables significant at P = 0.05 or better were sex, size, nodal status, and level of invasion. A new staging system is proposed that utilizes tumor size, invasion, grade, and nodal status. Actuarial 10-year survival was 100%, 76%, 29%, and 0% for Stages A, B, C and D, respectively (P values 0.22, 0.0007, and 0.01, respectively). Twelve patients undergoing APR received postoperative XRT; when compared by stage with APR alone no survival difference can be shown, although there is a trend towards fewer local recurrences. Of 26 patients (14 Stage B, 12 Stage C) receiving preoperative XRT (average 4000 R) before APR, 10 had inoperable tumors prior to XRT. All became operable. Eight patients had negative surgical margins and survival was equivalent stage for stage to the operable group (Stage B 78%, 5-year survival; Stage C 43%, 5-year survival). Eleven patients had no demonstrable primary tumor after XRT, although three had nodal metastasis. Five-year survival was 83% for this group. Thirty-one local recurrences were retreated for cure by surgery, XRT, or combination. Actuarial 5-year survival after retreatment was 38%. Thirty metachronous inguinal metastases were seen, 20 were retreated for cure, 18 by inguinal lymphadenectomy. Actuarial 5-year survival was 42%. Using a new staging system based on analysis of prognostic parameters for this disease, the outcome of combined surgery and XRT is compared. The efficacy of preoperative XRT for inoperable tumors is demonstrated. An appreciable salvage rate for local or inguinal recurrence was observed.