Abstract
OBJECTIVE: The aim of this study was to investigate the value of the 8th American Joint Committee on Cancer (AJCC) anatomic and prognostic stage groups for penile cancer patients and explore whether there is room for improvement. METHODS: The clinical and histopathologic data from 16 centers between January 2000 and December 2021 were assessed according to the 8th AJCC anatomic and prognostic stage groups. Kaplan-Meier plots were used to estimate the disease-specific survival (DSS) of the patients. The accuracy of the staging systems was investigated using the Harrell's concordance index (C-index). RESULTS: According to the 8th AJCC anatomic and prognostic stage groups, the 5-year DSS rates for patients with stages 0is/a, I, IIA, IIB, IIIA, IIIB, and IV disease were 100%, 99%, 86%, 81%, 66%, 34%, and 23%, respectively (p (0is/a-I)=0.8, p (I-IIA)<0.001, p (IIA-IIB)=0.5, p (IIB-IIIA)<0.001, p (IIIA-IIIB)<0.001, p (IIIB-IV)=0.004, and p (Total)<0.001). According to the modified model 1 system, the 5-year DSS rates without survivorship overlap for patients with stages 0is/a, I, II, IIIA, IIIB, and IV disease were 100%, 99%, 88%, 66%, 34%, and 23%, respectively (p (0is/a-I)=0.8, p (I-II)<0.001, p (II-IIIA)=0.002, p (IIIA-IIIB)<0.001, p (IIIB-IV)=0.004, and p (Total)<0.001). Similarly, according to the modified model 2 system, the 5-year DSS rates without survivorship overlap for patients with stages 0is/a, I, II, IIIA, IIIB, and IV disease were 100%, 99%, 86%, 66%, 34%, and 23%, respectively (p (0is/a-I)=0.8, p (I-II)<0.001, p (II-IIIA)=0.008, p (IIIA-IIIB)<0.001, p (IIIB-IV)=0.004, and p (Total)<0.001). The C-index scores of the simple modified staging systems were not inferior to those of the AJCC anatomic and prognostic stage groups. These results were confirmed by the bootstrap internal validation. CONCLUSION: There is still room for improvement about the 8th AJCC anatomic and prognostic stage groups. The improved models, which are more concise and convenient, have similar prediction accuracy.