Conditional survival predictions after surgery for patients with penile carcinoma

Conditional survival (CS) implies that, on average, long-term cancer survivors have a better prognosis than newly diagnosed individuals. The objective of the current study was to devise an accurate predictive tool that accounts for CS in men diagnosed with penile cancer.

Overall, 1245 patients treated with primary tumor excision (PTE) for pT(1-3)M0 squamous cell carcinoma of the penis (SCCP) between 1998 and 2006 were identified. Cox regression models were fitted for prediction of cancer-specific mortality (CSM). Nomogram development for prediction of CSM using CS methodology at 2 and 5 years was performed on 670 patients. External validation and calibration of the conditional nomogram was performed in 575 patients.

The 5-year CSM-free survival of patients at surgery was 84.3% and increased to 95.0% and 97.8% after 2 and 5 years of disease-free survival (DFS), respectively. The predicted probabilities varied by as much as 49% (57% vs 85%) when, for example, predictions of CSM-free survival at 5 years were made after PTE versus after 2 years of DFS. Within the external validation cohort, the accuracy of the conditional nomogram was 75.3% and 78.1% at 2 and 5 years after PTE.

The authors developed and externally validated the first conditional nomogram for predicting SCCP CSM-free survival that allows consideration of the length of survivorship.