[A Case of More Than Five-Year Survival of Carcinoma Associated with Anal Fistula Effectively Treated by Combined Modality Therapy].

The patient was a 56-year-old man who presented with perianal pain and a perianal abscess. After admission, he underwent debridement and colostomy due to poor control of the perianal abscess. Following a biopsy of the resected specimens, he was diagnosed with adenocarcinoma in the anorectal fistula. CT and MRI revealed that the tumor had invaded into the internal obturator muscle. Therefore, preoperative chemoradiotherapy and chemotherapy were given for locally advanced cancer. Subsequent to tumor shrinkage, we performed an abdominoperineal resection. Histopathologically, no cancer cells were detected on the surgical margin, and the effect of the preoperative therapy was judged to be Grade 1b. There has been no indication of recurrence of cancer after 5 years.