Outcomes of surgical treatment in patients with anorectal fistula cancer.

Background: No standard treatment for anorectal fistula cancer, such as multidisciplinary therapy, has been established due to the rarity of the disease. Herein, we investigated patients with cancer associated with anorectal fistula who underwent surgery to clarify the clinicopathological characteristics and to propose future perspectives for treatment strategies.
Case Presentation: Seven patients with cancer associated with anorectal fistula who underwent rectal amputation in our institute were analyzed with regard to clinical characteristics, pathological findings, surgical results, and prognosis. Four cases had Crohn's disease as an underlying cause. All seven cases were diagnosed as advanced stage. Preoperative [ ¹⁸ F]-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography/computed tomography (FDG-PET/CT) showed abnormal FDG accumulation in six cases including four mucinous adenocarcinomas. Three cases that received preoperative hyperthermo-chemoradiotherapy achieved pathological R0 resection. Postoperative recurrence was observed in four cases including three with Crohn's disease and one resulting in death.
Conclusions: Anorectal fistula cancer is rare and difficult to be diagnosed at early stages. Mucinous adenocarcinoma associated with anorectal fistula tends to exhibit abnormal FDG accumulation by FDG-PET/CT unlike common colorectal mucinous adenocarcinoma. Preoperative hyperthermo-chemoradiotherapy may be effective in obtaining pathological complete resection.