Objective: To evaluate the prognostic factors of penile cancer and the utility of prognostic models.
Methods: We analyzed postoperatively collected data of 311 patients diagnosed with penile cancer. Survival analysis (Kaplan–Meier and cox regression methods) was performed on this cohort. The c-index was used to determine the predictive accuracies of potential prognostic factors. The accuracies of four prognostic models were also evaluated, which were AJCC prognostic stage group for three recent editions, and four nomograms constructed by the Surveillance, Epidemiology, and End Results program (SEER). Two novel nomograms using our data were created and AUC of 2-year survival were determined to compare existing and newly established models.
Results: Tumor site, T and N stages, nuclear grade and lymph vascular invasion (LVI) significantly influenced prognosis. The 8th T and N stages had better c-indexes than former editions, while no improvement was seen in the 8thAJCC stage group. 6th AJCC+grade nomogram had a higher c-index than other three nomograms (SEER+grade, 6th TNM+grade, and 6th T_1-3N_0-3+grade nomograms; c-index: 0.831 vs 0.738, 0.792 and 0.781). New nomogram 1 included the 8th T and N stages, tumor site, nuclear grade, and LVI, with a c-index of 0.870. Novel nomogram 2 replaced the T and N stages with the AJCC stage group, which had a lower c-index of 0.855. The order of prediction accuracy of 2-year survival in the old and new models is consistent with the c-index results.
Conclusion: Tumor site, stages, grade, and LVI play important roles in predicting survival of penile cancer. The 8th stages have better predictive accuracy than former editions. We proposed two models with better predictive accuracy than former models; specifically, nomogram 1 may be a more precise and convenient tool for predicting penile cancer outcomes.
Keywords: penile cancer, TNM stage, survival, nomogram, external validation