Clinical Outcomes and Prognostic Factors of Concurrent Chemoradiotherapy for Anal Squamous Cell Carcinoma in Japan

Abstract

Abstract Background Concurrent chemoradiotherapy (CCRT) is the standard treatment for locoregional anal squamous cell carcinoma (ASCC) in Western countries. However, there have been few reports on the clinical outcomes of CCRT in Japan. This study aimed to evaluate the clinical outcomes of CCRT, prognostic factors, and the clinical impact of programmed cell death-ligand 1 (PD-L1) expression of ASCC in Japan. Methods Patients with locoregional ASCC were enrolled between 2007 and 2017. All patients received CCRT consisting of ≥ 45 Gy of radiation, 5-fluorouracil, and mitomycin C. Disease-free survival (DFS), overall survival (OS), and adverse events (AEs) were estimated. The expression of p16 and PD-L1 was evaluated using immunohistochemical staining (IHC). Results This study included 36 patients, of whom 30 (83.3%) were female. Among the participants, 32 (88.9%) achieved complete clinical remission, while six (16.7%) experienced recurrence. The five-year DFS and five-year OS were 72.2% and 84.7%, respectively. Major AEs of grades ≥ 3 included neutropenia in 10 (27.7%) and perianal dermatitis in eight (22.2%). In a univariate analysis, male sex, lymph node metastasis, and large tumor size were significantly associated with worse outcomes. In a multivariate analysis, tumor size was an independent factor related to short DFS. Of the 30 patients whose biopsy specimens were available for IHC, 29 (96.7%) were positive for p16, and 13 (43.3%) were positive for PD-L1. However, PD-L1 expression did not show any clinical impact. Conclusions The comparative etiology, clinical outcomes, and prognostic factors of CCRT observed in Japanese patients with locoregional ASCC were consistent with Western data.