Selecting Patients with Small Renal Masses for Active Surveillance: A Domain Based Score from a Prospective Cohort Study

Abstract

Purpose: We sought to identify predictors of active surveillance in a prospective cohort study of patients with a small renal mass demonstrating favorable outcomes. We generated a summary score to discriminate patients selected for active surveillance or primary intervention.

Materials and methods: We analyzed the records of 751 patients from 2009 to 2018 who were enrolled in the DISSRM (Delayed Intervention and Surveillance for Small Renal Masses) Registry to compare active surveillance and primary intervention in the domains of demographics, tumor characteristics, comorbidity and patient reported quality of life. Regression models were created to assess univariable and multivariable model discrimination by the AUC and quality by the AIC (Akaike information criterion). The DISSRM score was based on the most predictive combination of variables and validated for its association with overall survival by Kaplan-Meier survival curves and a Cox proportional hazards regression model.

Results: Of the patients 410 (55%) elected active surveillance and 341 (45%) elected primary intervention. Of the domains patient age, the Charlson comorbidity index, tumor diameter and the SF-12® Physical Component Score had the greatest discrimination for clinical selection into active surveillance. These domains made up the DISSRM score (AUC 0.801). The maximum DISSRM score was 7. The average score for active surveillance was 4.19 (median 4, IQR 2-6) and 72% of scores were 4 or greater. The average score for primary intervention was 3.03 (median 3, IQR 1-5) and 63% of scores were 3 or less. A higher DISSRM score was associated with worse overall survival, for example a score of 6-7 had a HR of 10.45 (95% CI 1.25-87.49, p = 0.03).

Conclusions: The DISSRM score represents a measure of oncologic and competing risks of death in various important domains in patients with a small renal mass. It could be used to guide the management selection. Patients with intermediate scores that express illness uncertainty may require additional workup, such as confirmatory biopsy, to reach a treatment decision.

Keywords: carcinoma; kidney;; mortality; renal cell; risk assessment; watchful waiting.