Surveillance for small renal masses: retrospective analysis of a cohort of 42 patients with long-term follow-up

To provide our experience with active surveillance in patients incidentally diagnosed with small renal masses and show the results of long-term follow-up. We retrospectively evaluated a cohort of 42 patients diagnosed with small renal mass (a parts per thousand currency sign4 cm in diameter). All patients had clinical and radiological follow-up every 6 months. We evaluated the differences between patients who remained on surveillance and those who underwent surgical delayed intervention and the correlations between clinical variables and size growth rate. The mean patients' age was 75 years (66-90); the mean follow-up was 69.4 months (range 35-168). The median initial tumor size at presentation was 2.5 cm (range 1-4.3), and the median estimated tumor volume was 8.6 cm(3) (range 1.7-42.3). The median growth rate of the cohort was 0.8 cm/year (range 0.2-2.9), and the median volumetric growth rate was 9.1 cm(3)/year (range 0-19.6). Death for metastatic disease occurred in 2 patients died due to metastatic disease (4.7 %). No correlation was found between initial tumor size and size growth rate. The mean growth rate of the group of patients who underwent surgery was higher than in those who remained on surveillance (1.8 vs. 0.4 cm/year; P < 0.001). The most of small renal masses initially managed by surveillance will grow slowly and will have a low metastatic potential. Tumor size at diagnosis is not able to predict the natural history of renal masses, even if malignant disease may have a higher growth rate. In elderly patients with relevant co-morbidities, surveillance can be a reasonable option alternative to surgery.