Synchronous and metachronous colon lesions in squamous cell carcinoma of the anal canal.

The charts of 79 patients with a histologic diagnosis of squamous cell carcinoma of the anal canal were reviewed to determine the incidence of synchronous and/or metachronous colon lesions. Forty-six patients underwent an adequate preoperative evaluation of the colon and rectum. Ten patients underwent colonoscopy, 33 patients underwent a barium enema, and three patients underwent colonoscopy and a barium enema. In this group six adenomatous polyps and three hyperplastic polyps were discovered. An adenocarcinoma of the sigmoid colon was found in another patient six months prior to the diagnosis of a squamous cell carcinoma of the anal canal. Twenty-three patients had follow-up evaluation of the large bowel for metachronous lesions following treatment of the squamous cell carcinoma of the anal canal. Ten patients underwent colonoscopy, three patients had a barium enema, and ten autopsies were available for analysis. In this group metachronous lesions consisted of two adenomatous polyps and one hyperplastic polyp.