Conditional survival predictions after surgery for patients with penile carcinoma

BACKGROUND: 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. METHODS: Overall, 1245 patients treated with primary tumor excision (PTE) for pT1-3M0 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. RESULTS: 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. CONCLUSIONS: The authors developed and externally validated the first conditional nomogram for predicting SCCP CSM-free survival that allows consideration of the length of survivorship. Cancer 2011;. © 2011 American Cancer Society.