The use of active surveillance as primary management for small renal tumors is increasing, but data on patient outcomes remains limited, wrote Paul L. Crispen, MD, in a “News and Views” piece for the May 2013 issue of Nature Reviews Urology (2013;10:255-256).

In an interview with Renal & Urology News, Dr. Crispen, Assistant Professor of Urology at the University of Florida in Gainesville, highlights the advantages and challenges of active surveillance for small renal masses.

How did the topic of active surveillance for renal masses capture your interest?

Dr. Crispen: I first became interested in the active surveillance of renal masses during my urology residency. At the time our experience was quite limited, with the majority of data merely focusing on growth rates of renal masses. There was little information on predictors of growth rates, tumor histology, or the potential impact of a period of active surveillance on eventual therapy. This limited information was a source of opportunity to explore more about the natural history of renal masses.

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For these reasons we began evaluating the relationship between tumor histology and observed tumor growth and changes in management strategy based upon length of delay between diagnosis and treatment. Through our work and that being done at other institutions we began to appreciate the indolent nature of most small renal tumors. While most of our initial experience was based upon patients who were too high-risk for surgery or those refusing treatment, we realized that active surveillance had the potential to be utilized in other select patient populations presenting with small renal masses.

Why is active surveillance for renal masses gaining attention as a non-treatment strategy now?

Dr. Crispen: Through active surveillance series we have learned that the majority of small renal masses will grow slowly over time and are associated with a low risk of metastatic progression.  Active surveillance may thus provide select patients with a means of avoiding treatment-related morbidity including surgical complications and decreased renal function.

Is there anything about the specific mechanics of the kidney or kidney cancer that make active surveillance for this disease either a particularly effective or challenging option?

Dr. Crispen: The greatest challenge in recommending a patient to undergo active surveillance is the potential for metastatic progression.  At the present time there are no established guidelines for who should initiate a period of active surveillance or when active surveillance should be terminated and definitive therapy be performed.

Which patients (or lesions) are best suited to active surveillance?

Dr. Crispen: When selecting a patient for active surveillance it is important to consider both tumor- and patient-related features. Small—less than 3 cm—asymptomatic masses are likely the best candidates for this approach. There are limited data on renal masses greater than 4 cm and I would only advise this approach in patients who are not surgical candidates or have a known benign histology. Life expectancy, renal function, performance status, and overall surgical candidacy are important patient-related factors that should be considered in all cases.