Available active surveillance follow-up protocols for small renal mass: a systematic review

Purpose: To evaluate follow-up strategies for active surveillance of renal masses and to assess contemporary data. Methods: We performed a comprehensive search of electronic databases (Embase, Medline, and Cochrane). A systematic review of the follow-up protocols was carried out. A total of 20 studies were included. Result: Our analysis highlights that most of the series used different protocols of follow-up without consistent differences in the outcomes. Most common protocol consisted in imaging and clinical evaluation at 3, 6, and 12 months and yearly thereafter. Median length of follow-up was 42 months (range 1–137). Mean age was 74 years (range 67–83). Of 2243 patients 223 (10%) died during the follow-up and 19 patients died of kidney cancer (0.8%). The growth rate was the most used parameter to evaluate disease progression eventually triggering delayed intervention. Maximal axial diameter was the most common method to evaluate growth rate. CT scan is the most used, probably because it is usually more precise than kidney ultrasound and more accessible than MRI. Performing chest X-ray at every check does not seem to alter the clinical outcome during AS. Conclusion: The minimal cancer-specific mortality does not seem to correlate with the follow-up scheme. Outside of growth rate and initial size, imaging features to predict outcome of RCC during AS are limited. Active surveillance of SRM is a well-established treatment option. However, standardized follow-up protocols are lacking. Prospective, randomized, trials to evaluate the best follow-up strategies are pending.