AUA 2018: Conditional Survival and Landmark Analysis for Patients with Small Renal Masses Undergoing Active Surveillance at a Tertiary Care Center

San Francisco, CA (  Conditional survival can provide guidance for patients once they have survived a period of time after diagnosis of their disease. In this study, the authors determined conditional survival for patients with small renal masses (SRM) undergoing active surveillance (AS). 

Patients were enrolled in a prospective AS registry at the authors’ institution between May 2005 and January 2016. Patients with localized SRM 4cm were included, with serial radiologic imaging available in-house for re-review. Overall survival (OS) was estimated using the Kaplan-Meier method and modeled via Cox proportional hazards models. The primary end points analyzed were the conditional probability of survival and tumor growth over time. Landmark analysis was used to evaluate survival outcomes beyond the 2-year mark after the initial scan. 

A total of 272 patients were included in this analysis. Mean initial tumor size was 1.74 (0.77) cm and mean tumor size closest to the 2-year mark was 1.97 (0.83) cm. The likelihood of continued survival to 5 years improved after the 2-year landmark was reached. Patients with a tumor size between 3-4 cm were at a greater risk of non-renal cell carcinoma death (HR>3.5; p<0.001). A linear mixed effects model revealed slow tumor growth (beta: 0.12; p < 0.001) for tumors <3 cm. Adjusted tumor size predictions disclosed parallel growth rates for SRM of <2cm and 2-2.99cm with an insignificant difference in growth rates (p = 0.969), as can be shown in the Figure.

overall survival by tumor size copy
Figure: Overall survival by initial tumor size (A) and adjusted predictions from linear mixed effects model predicting tumor size over time (B) for patients with small re3nal masses (SRM) undergoing active surveillance (AS).

The authors concluded that their study provides insight into the survival of patients with SRM on AS who have already survived a certain period of time. The conditional survival probability of patients with SRM <3cm on AS improved after the initial 2 years, suggesting a role for re-counseling for those who survive to the 2-year landmark. Patient factors (renal function and CCI) were significantly associated with survival at baseline and at the 2-year landmark.

Presented by: Firas Petros, Houston, TX, USA

Written by:  Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre @GoldbergHanan at the 2018 AUA Annual Meeting - May 18 - 21, 2018 – San Francisco, CA USA