Renal cell carcinoma and body composition: Results from a case-control study

Background: Recent studies have found modest increases in risk for renal cell carcinoma (RCC) among those with high relative weight and body fat. The present study used a case-control design to further evaluate associations between RCC and body composition. Methods: Incident cases of RCC (n = 335) were identified from Florida hospital records and the state cancer registry, and population controls (n = 337) were identified from random-digit dialing. In-person interviews included height, weight, waist and hip size, skinfold thickness, and body fat percentage measurements. Odds ratios and 95% confidence intervals were calculated using logistic regression, controlled for age, sex, race, and smoking. Results: Cases were more likely than controls to be obese (BMI > 30)(OR = 1.53; 95% CI: 1.12 – 2.10) and to have 40% or greater body fat percentage (OR = 1.73; 95% CI: 1.16 –2.57), associations that were stronger among whites and men. Dose-response associations for both measures were significant at p = 0.022 and p = 0.001, respectively. Cases were more likely to have a waist-to-hip ratio greater than 1.00 (OR = 1.60; 95% CI: 1.03 – 2.49), especially among African-Americans. Skinfold measurements were greater among cases than controls at the thigh (p= 0.02) and trunk (p = 0.02). Correlation statistics demonstrated BMI to be a reliable indicator of body fat percentage (r = 0.67, p = 0.000). Conclusion: Risk of RCC increases between 50% and 70% for those scoring high on obesity indicators, which may explain the rising trend in RCC incidence in the U.S.