Active surveillance of small kidney masses is a safe and effective alternative to immediate surgery. The overall and cancer specific survival rates are similar for both approaches.

Currently, active surveillance is primarily used to treat elderly patients who have complex health issues or decline surgery. Notably, this study suggests that active surveillance could be safely extended to other selected patients.

Lead author Nilay Patel, MD, of the Department of Urology at Churchill Hospital, Oxford, United Kingdom, explained that the more sophisticated imaging techniques have led to an increasing incidence of kidney cancer in Europe and the United States. Smaller masses of less than 4 cm are being detected at earlier stages. Dr. Patel said, “This has led to an increased rate of surgery for small kidney masses, but the benefits of this remain unclear. Conflicting reports on improvements in death rates for kidney cancer over the last few years suggest that increased detection may not necessarily be improving survival rates for patients with smaller tumors inside their kidney.”

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This study included 202 patients with 234 small renal masses of less than 4 cm inside their kidney, which were classified as T1a. Among these patients, 90 were managed with a partial nephrectomy, 41 with radical nephrectomy, and 71 with active surveillance.

Over a median follow-up period of 34 months, the mean growth rate of kidney masses that were under active surveillance was 0.21 cm. Moreover, 53% of the small renal masses in these patients had negative or zero growth.

Overall and cancer-specific survival rates did not have statistically significant differences between patients under active surveillance and those who received partial or radical nephrectomy. The overall survival rates were 83% for active surveillance, 80% for radical nephrectomy, and 90% for partial nephrectomy. The cancer-specific survival rates were 99% for active surveillance, 93% for radical nephrectomy, and 97% for partial nephrectomy.

“Our research suggests that active surveillance of small kidney masses offers similar cancer outcomes to radical or partial surgery in the short and intermediate term,” said Patel.

This research was published in BJUI (2012; doi:10.1111/j.1464-410X.2012.11130.x).