WCE 2018: Small Renal Masses – Active Surveillance

Paris, France (UroToday.com) The incidence of renal cancer has been increasing in the last two decades, whereas the mortality rate from renal cancer stays stable. One might think that the excellent treatment modalities result in stable mortality rate. However, it is rather the overdiagnosis of indolent tumors (due to increased use of ultrasound and computed tomography) that drives better “cure rates”, as the mortality rate of aggressive tumors remains stable. As the rate of benign pathology of renal masses is 21% for tumors <3 cm (14% for all tumors), active surveillance (AS) is in fact, the most minimally invasive approach to renal tumors. Its rationale is to avoid overtreatment of indolent tumors, especially in patients with competing risks of death. The American Urological Association guideline on Renal Mass and Localized Renal Cancer recommends active surveillance as an option for initial management, especially for indolent tumors smaller than 2 cm.

Several studies have shown that AS is a safe approach. Based on the DISSRM registry, 5-year cancer-specific survival was similar between patients electing AS or intervention (99-100%). In another large series of patients on AS, 5-year cancer-specific mortality was 1.2%. The majority of small renal tumors are indolent (Figure 1) and over 75% of tumors grow at a rate of less than 5 mm per year. When a tumor is closely monitored and grows at a rate higher than expected for a benign lesion, delayed intervention is recommended.

UroToday WCE2018 correlation between tumor size and aggressive histology
Figure 1. correlation between tumor size and aggressive histology

In general, renal mass biopsy prior to initiating AS is recommended only if it would change management. Indolent malignant tumors such as low grade clear cell RCC, chromophobe, or papillary type I have low malignant potential and are therefore suitable for AS (Figure 2). Recommended imaging interval is 3-6 months initially. When the tumor is stable in size and there are more competing risks for death, intervals can be extended.

UroToday WCE2018 Proposed algorithm for active surveillance
Figure 2. Proposed algorithm for active surveillance.

Presented by: David Duchene, MD, Professor, Department of Urology, University of Kansas Medical Center, USA

Written by: Shlomi Tapiero, MD, Department of Urology, University of California-Irvine, medical writer for UroToday.com at the 36th World Congress of Endourology (WCE) and SWL - September 20-23, 2018 Paris, France

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