title: A case of perianal mucinous adenocarcinoma arising from an anorectal fistula successfully resected after preoperative radiotherapy.
abstract: A case of mucinous adenocarcinoma arising on a long-standing anorectal fistula is described. A 60-year-old man with a long history of mucinous discharge, pain and perianal induration underwent a biopsy of the external opening of the fistula that showed a mucinous infiltrating adenocarcinoma. Due to the large size of the tumor and the fact that it had extended into the surrounding tissue, preoperative radiotherapy was performed. Radiotherapy was given with 40 Gy in 25 fractions for 5 weeks through posterior and bilateral portals. After radiotherapy the tumor was markedly shrunk and the serum level of carcinoembryonic antigen was also improved. Abdominoperineal resection was performed 8 weeks after the termination of radiotherapy. Histological examination of the resected specimen revealed that the invasion of the tumor remained within the sphincter muscle and that no cancer cells were present on the surgical margin. The histological effect of radiotherapy was judged as grade 1b. This treatment can result in downstaging and R0 resection, which also has a possibility to prevent local recurrence. This case suggests that preoperative radiotherapy may play an important role in the definitive treatment of locally advanced perianal mucinous adenocarcinoma.
authors.affiliation: Department of Surgery, Institute of Gastroenterology, Kawasaki Saiwai Hospital, Kawasaki, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Ohta
authors.forename: Koji
authors.initials: K
authors.lastname: Sekikawa
authors.forename: Manabu
authors.initials: M
authors.lastname: Goto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Narita
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Hironari
authors.initials: H
authors.lastname: Ikeda
authors.forename: Masataka
authors.initials: M
authors.lastname: Oneyama
authors.forename: Yudai
authors.initials: Y
authors.lastname: Hirata
authors.forename: Mikihiro
authors.initials: M
authors.lastname: Nakayama
authors.forename: Yohta
authors.initials: Y
authors.lastname: Shimoda
authors.forename: Syun
authors.initials: S
authors.lastname: Sato
keywords: Anorectal fistula; Perianal mucinous adenocarcinoma; Preoperative radiotherapy