Disease-free survival as a predictor of overall survival in localized renal cell carcinoma following initial nephrectomy: а retrospective analysis of Surveillance, Epidemiology and End Results-Medicare data
Summary. Objectives. This study aimed to assess whether disease-free survival (DFS) may serve as a predictor for long-term survival among patients with intermediate-high risk or high risk renal cell carcinoma (RCC) post-nephrectomy when overall survival (OS) is unavailable. Methods. The Surveillance, Epidemiology and End Results-Medicare database (2007–2016) was used to identify patients with non-metastatic intermediate-high risk and high risk RCC post-nephrectomy. Landmark analysis and Kendall’s τ were used to evaluate the correlation between DFS and OS. Multivariable regression models were used to quantify the incremental OS post-nephrectomy associated with increased time to recurrence among patients with recurrence, adjusting for baseline covariates. Results. A total of 643 patients were analyzed; mean age of 75 years; >95% of patients had intermediate-high risk RCC at diagnosis; 269 patients had recurrence post-nephrectomy. For patients with versus without recurrence at the landmark points of 1, 3, and 5 years post-nephrectomy, the 5-year OS were 37.0% versus 70.1, 42.3 versus 72.8, and 53.2 versus 78.6%, respectively. The Kendall’s τ between DFS and OS post-nephrectomy was 0.70 (95% confidence interval (CI) 0.65, 0.74; p<0.001). After adjusting for baseline covariates, patients with one additional year of time to recurrence were associated with 0.73 years longer OS post-nephrectomy (95% CI 0.40, 1.05; p<0.001). Conclusion. The significant positive association of DFS and OS among patients with intermediate-high risk and high risk RCC post-nephrectomy from this study supports the use of DFS as a potential predictor of OS for these patients when OS data are immature.
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