[A case of carcinoma associated with anal fistula resected after preoperative chemoradiotherapy].

A 66-year-old man with a 39-year history of anal fistula was admitted to our hospital for anal pain and bleeding. Fistulectomy was carried out for anal fistula. Histological examination of the specimen revealed carcinoma associated with anal fistula. A computed tomography showed that the tumor had invaded the prostate. Therefore, preoperative chemoradiotherapy(S-1 plus radiation 40 Gy/body)for locally advanced cancer was performed. Magnetic resonance imaging showed that the boundary between the tumor and the prostate was unclear, but we performed an abdominoperineal resection and the prostate was fully preserved. Histopathologically, no cancer cell existed on the surgical margin. The histological effect of chemoradiotherapy was judged as grade 2. This case suggested that surgical treatment combined with preoperative chemoradiotherapy may be effective for locally advanced carcinoma associated with anal fistula, in which preservation of adjacent organs is considered to be difficult.