Conditional survival predictions after nephrectomy for renal cell carcinoma.

PURPOSE: Conditional survival implies that on average long-term cancer survivors have a better prognosis than do newly diagnosed individuals. We explored the effect of conditional survival in renal cell carcinoma.
MATERIALS AND METHODS: We studied 3,560 patients with renal cell carcinoma of all stages treated with nephrectomy. We applied conditional survival methodology to a previously reported posttreatment nomogram predicting survival after nephrectomy for patients with renal cell carcinoma stage I to IV. We used the same predictor variables that were integrated in the original multivariable Cox regression models, namely TNM stage, Fuhrman grade, tumor size and symptom classification. To validate the conditional survival nomogram we used an independent cohort of 3,560 patients from 15 institutions.
RESULTS: The 5-year survival of patients immediately after nephrectomy was 74.2%, which increased to 80.4%, 85.1%, 90.6% and 89.6% at 1, 2, 5 and 10 years after nephrectomy, respectively. The predicted probabilities varied by as much as 50% when, for example, predictions of renal cell carcinoma specific mortality at 10 years were made after nephrectomy vs 5 years later. Within the external validation cohort the accuracy of the conditional nomogram was 89.5%, 90.5%, 88.5% and 86.7% at 1, 2, 5 and 10 years after nephrectomy.
CONCLUSIONS: We developed (2,530) and externally validated (3,560) a conditional nomogram for predicting renal cell carcinoma specific mortality that allows consideration of the length of survivorship. Our tool provides the most realistic prognosis estimates with high accuracy.