2025 年 9 巻 4 号 p. 385-397
Objectives: In this study, we aimed to present the clinicopathological features of anal canal carcinomas based on differentiation and clarify whether differentiation affects prognosis.
Methods: We included 597 patients with adenocarcinoma registered in the multicenter colorectal cancer registry data of the Colorectal Cancer Study Group. We also included 151 patients with squamous cell carcinoma enrolled by the 47 medical affiliates of the Colorectal Cancer Study Group in a multicenter cohort study conducted in Japan. The clinicopathological features by differentiation and prognostic factors of each histological type were examined retrospectively.
Results: The clinicopathological features of adenocarcinoma were similar to those of rectal carcinoma by differentiation. In contrast, the clinicopathological features of squamous cell carcinoma did not differ according to differentiation. Differentiation was a prognostic factor in patients with adenocarcinoma (G3/4; hazard ratio: 1.91, 95% confidence interval: 1.22-3.01, p=0.0043) but not in patients with squamous cell carcinoma.
Conclusions: Differentiation was a prognostic factor for adenocarcinoma in anal canal carcinoma; thus, differentiation should be considered in the treatment strategy. However, differentiation was not a prognostic factor in squamous cell carcinoma. Further studies should explore the involvement of differentiation in squamous cell carcinoma treatment.
