Is total colonic evaluation for anal cancer necessary?

The purpose of this study was to evaluate the necessity of total colonic evaluation in patients diagnosed with anal cancer. We reviewed the cases of 69 patients treated for neoplasm of the anus from January 1973 through November 1998. Patients underwent a barium enema, flexible sigmoidoscopy or colonoscopy; findings from these procedures were analyzed. Anal pathology included: squamous cell carcinoma, 48 patients (72%); adenocarcinoma, 6 patients (9%); and squamous cell carcinoma in situ, 10 patients (15%). Chemoradiation was completed in 41 patients (61%), and 6 patients (9%) underwent abdominal perineal resection. Wide excision was the primary therapy in 15 patients (22%). Procedures included: colonoscopy, 31 patients (46%); flexible sigmoidoscopy only, 15 patients (22%); barium enema only, 3 patients (5%); and a combination of flexible sigmoidoscopy and barium enema, 18 patients (27%). Eighty-five per cent of patients had a normal colonic evaluation. Ten patients (15%) had single or multiple polyps identified. Six adenomatous polyps and two hyperplastic polyps were found. No synchronous colorectal malignancy was identified. We conclude that colonoscopy is an integral part of colonic surveillance in patients diagnosed with anal carcinoma, but our study fails to find evidence to support such intervention. The standard screening recommendation for colorectal cancer based on age and risk factors is appropriate intervention for patients diagnosed with anal cancer; anal cancer itself does not appear to be one of these risk factors.