A comparative study of AJCC and the modified staging system in pT2/pT3 penile squamous cell carcinoma – a validation on an external data set

Aims The recent changes in the American Joint Commission on Cancer, 8th edition (AJCC‐8E) pT2 and pT3 tumour definitions for penile cancer need robust validation studies. A recent study redefined and modified the pT2 and pT3 stages incorporating the histopathological variables (tumour grade, lymphovascular invasion, perineural invasion) similar to that used in the current AJCC‐8E pT1 stage tumour subclassification. In this study, we validate and compare this proposed staging with the AJCC staging systems on an external data set. Methods and results The data set from a previously published study was obtained. pT2 and pT3 stages were reconstructed as per AJCC 7th edition (AJCC‐7E), AJCC‐8E and the proposed staging. The staging systems were correlated with nodal metastasis, disease‐free survival (DFS), cancer‐specific survival (CSS) and overall survival (OS). All systems were compared using receiver operating characteristic (ROC) curves. A total of 281 cases formed the study cohort. AJCC‐8E ( P = 0.031) and the proposed staging ( P = 0.003) correlated with nodal metastasis on adjusted analysis, the latter with a better strength of association (AJCC‐8E, γ = –0.471; proposed, γ = –0.625). On adjusted analysis, all the staging systems had a significant correlation with DFS, while only AJCC‐8E and the proposed staging correlated with CSS and OS. On ROC curve analysis, the proposed staging had the highest area under the curve and was the only staging system to statistically correlate with all the outcome variables. Conclusions The proposed staging for pT2/pT3 tumour stages in penile cancer may improve the prognostic and predictive ability.