Defining the Optimal Management Strategy for Small Renal Masses.

Small renal masses are typically defined as solid, contrast enhancing kidney tumors under 4 cm in size, corresponding to American Joint Cancer Commission TNM stage T1a. They are most commonly asymptomatic and incidentally discovered, a classic by-product of increasing use of cross-sectional imaging for any variety of unrelated abdominal symptoms. The risk that a small renal mass represents a malignancy is closely tied to size with nearly 20% of tumors under 4 cm being benign. [1] Also, of the small renal masses that are kidney cancer, the majority have indolent histology with prolonged natural history. In this issue of the journal, Drs. Ellis and Messing provide a comprehensive review of the management of small renal masses [2]. They conclude that “short and intermediate-term data demonstrate that active surveillance with the option for delayed intervention is a safe management approach with similar survival outcomes to primary intervention (PI) at 2 and 5 years, is cost effective, and prevents overtreatment, especially in patients with significant comorbidities”. As with low-risk prostate cancer, over-detection and over-treatment of small renal masses is an important clinical problem. A 2017 study by Welch