Visceral obesity is associated with better recurrence-free survival after curative surgery for Japanese patients with localized clear cell renal cell carcinoma

Objective: To investigate the prognostic significance of visceral obesity to predict recurrence after curative surgery for Japanese patients with localized renal cell carcinoma. Methods: The data of 285 patients who underwent curative surgery for localized renal cell carcinoma were retrospectively reviewed. Median follow-up was 36.7 months. The association between visceral obesity and recurrence-free survival rate was evaluated using the Kaplan-Meier method and Cox regression models. Visceral fat area at the level of the umbilicus measured using pre-operative computed tomography was used as an index of visceral obesity. Results: Twenty-nine patients (10.2%) experienced recurrence. Five-year recurrence-free survival rates were 91.3% in high visceral fat area group (≥120 cm2) and 76.9% in low visceral fat area group (<120 cm²) (P = 0.037); however, visceral fat area was not an independent predictor of recurrence- free survival in multivariate analysis. In the patients with clear cell renal cell carcinoma, 28 patients (11.6%) experienced recurrence. Five-year recurrence-free survival rates were 88.7% in high visceral fat area group and 71.0% in low visceral fat area group (P = 0.043), and visceral fat area was an independent predictor of recurrence-free survival (hazard ratio: 1.974, P = 0.042) as well as C-reactive protein, Fuhrman nuclear grade, tumor size and microvascular invasion. In patients with organ confined clear cell renal cell carcinoma in particular, visceral fat area was also a useful and independent predictor of recurrence-free survival (hazard ratio: 2.807, P = 0.038). Body mass index was not useful in either cohort. Conclusions: High visceral fat area was a positive predictive biomarker for better recurrence-free survival after curative surgeries for localized clear cell renal cell carcinomas; however, body mass index was not a predictor.