Validation and Modification of the American Joint Commission on Cancer 8th Edition Staging System for Patients With Anal Squamous Cell Cancer: A Surveillance, Epidemiology and End Results Analysis

This study aimed to validate the clinical utility of American Joint Committee on Cancer (AJCC) 8th edition staging system for anal squamous cell cancer (ASCC). Further, Surveillance, Epidemiology, and End Results database (2004–2015) was used to validate the practicability of 8th AJCC stages. Disease-specific survival (DSS) and overall survival (OS) were evaluated using Kaplan-Meier analysis. Hazard ratios (HRs) were calculated using Cox regression analysis. Furthermore, the modification was validated using Kaplan-Meier analysis and calculating the concordance index (C-index). A total of 11891 patients with ASCC were analysed. the 5-year DSSs for stage I, IIA, IIB, IIIA, IIIB, IIIC, and IV were 93.8%, 87.4%, 76.2%, 76.9%, 72.0%, 66.1%, and 34.9%. We found the OS and DSS of IIIA patients showed better than IIB. After hazard analysis, modified IIIA patients showed worse OS and DSS than IIB. C-indexes were increased from 0.612 to 0.636 for DSS and from 0.566 to 0.582 for OS of stage II and III ASCCs. In conclusion, our study validated 8th AJCC staging system as overall suitable classification with a few defects. Thus, we suggested modifications in II and III stages to make it more suitable for ASCCs that could be adopted in clinical practice.