Chemoradiation For The Treatment Of Locoregional Squamous Cell Carcinoma Of The Anal Canal: A Single Center Retrospective Analysis In Japan.

851 Background: Squamous cell carcinoma of the anal canal (SCCA) is a rare malignancy. In western countries, chemoradiotherapy (CRT) has become the standard treatment for locoregional SCCA according to National Comprehensive Cancer Network guidelines. But only some small amount case reports have been found about CRT for SCCA in Japan. We retrospectively evaluated the results of CRT for SCCA at a single center in Japan. Methods: We had treated 33 patients with the concurrent CRT at the Cancer Institute Hospital between 2007 and 2017. RT consisted of 45.0 to 59.4 Gy given in 5 to 7 weeks, with a daily dose of 1.8 Gy. Chemotherapy was given during RT: 1000mg/m 2 daily fluorouracil (FU) as a continuous infusion on day 1 to 4 and 29 to 32, and a single dose of mitomycin C (MMC) 10mg/m 2 administered on day 1 and 29. Data on relapse and deaths were obtained until August 2017. Results: Of 33 patients who were treated with CRT, the median age was 59 (range 35-82) years. Male to female sex ratio was 1:4.5. Patients who had Eastern Cooperative Oncology Group Performance Status (ECOG PS) 0 were 88% and patients who had ECOG PS 1 were 12%. The clinical stages before CRT were cStage I in 9 (27%), II in 4 (12%), IIIA in 6 (18%) and IIIB in 14 (42%). Although clinical complete response (CR) was observed in 29 patients of 33 (88%), 5 patients of 29 recurred. No patients recurred in cStage I and II. SCCA remained or recurred in 2 patients of 6 in cStage IIIA and 7 patients of 14 in cStage IIIB. 3-year disease free survival (DFS) was 71.3% (95%CI: 52.0-84.0%), and 3-year overall survival was 81.8% (95%CI: 55.1-92.8%). Conclusions: CRT for SCCA resulted in clinically meaningful impact on DFS and OS in our hospital. Therefore, CRT may be the standard of treatment also in Japan.