Active surveillance for small renal tumors: have clinical concerns been addressed so far?

The incidence of small renal masses is increasing, as a result of the wide adoption of imaging exams. Their management, however, is complicated, especially in patients with decreased life expectancy or comorbidities. Approximately 20% of small renal masses are benign and, even if malignant, just 10% show aggressive pathological features. Furthermore, competing cause mortality seems to exceed the cancer-specific mortality in patients aged over 70 years. The role of percutaneous tumor biopsy is still not well defined. All these observations raise the concern as to whether surgery might represent an overtreatment for some cases of small renal masses, calling into question the role of active surveillance. The aim of this review was to evaluate the current evidence pertaining to several hot questions that need to be addressed when contemplating active surveillance for small renal masses. The most relevant publications on this subject available in the literature were selected. Five representative series of active surveillance along with the main related variables were identified. Some relevant items surrounding the field of active surveillance were identified and submitted to an evidence-based discussion. According to the recent evidence, small renal masses under active surveillance tend to show an indolent course with a low probability of disease progression, the latter being triggered most of the time by a tendency to grow faster. Unfortunately, we are currently unable to predict those few cases with aggressive behavior. According to the current evidence, active surveillance is feasible and safe in elderly and comorbid patients.