Incidence of benign versus malignant renal tumors in selected studies.

Abstract

357 Background: Use of cross-sectional imaging has increased the detection rate for small renal tumors; more patients now present with early-stage renal cell carcinoma (RCC) or benign or indolent renal masses. Histopathology after surgical resection is the definitive method for characterizing renal tumors. Stage migration of renal masses creates uncertainty about the percentage of resected masses that will be benign vs malignant. We sought to better define these proportions through a targeted review of the literature. Methods: PubMed/select congresses were searched to identify the histologic classification of renal masses in a representative sample from the contemporary literature: [search] incidence AND (renal cell carcinoma AND benign); incidence AND (renal tumor AND benign); percentage AND (renal cell carcinoma AND benign); limit: 2003–2011. Results: Most representative studies included procedures conducted in the mid-1990s to the mid-to-late 2000s. Studies origin was US (n=8), Korea (n=3), China, Japan, Germany, Austria, Australia, and multisite (Israel/France/US; all n=1). Only 8 studies had n≥500 (range, 70–10,404). The proportion of benign masses are shown (see Table); half of the studies reported values between 16% and 17%. The majority found that benign tumors were more likely to be smaller in size (<4 or <7 cm) than malignant tumors. 11 studies reported the RCC subtype (% clear cell range, 46%–83%). Conclusions: Benign renal tumors occur ~15% of the time and are more prevalent among small masses. Nearly 25% of resected lesions are benign or indolent and may not require surgery. Preoperative discrimination of more aggressive renal masses would be an important clinical advance that could improve clinicians’ diagnostic confidence and guide patient management. Funding: Wilex AG/IBA Molecular. [Table: see text]