Obesity, adipokines, and prostate cancer in a prospective population-based study.

BACKGROUND: The purpose of this investigation was to examine the association of obesity and the adipokines leptin, adiponectin, and interleukin-6 (IL-6) with prostate cancer risk and aggressiveness. METHODS: One hundred twenty-five incident prostate cancer cases and 125 age-matched controls were sampled from among participants in the original San Antonio Center for Biomarkers of Risk of Prostate Cancer cohort study. The odds ratios (OR) of prostate cancer and high-grade disease (Gleason sum >7) associated with the WHO categories of body mass index (kg/m(2)) and with tertiles of serum concentrations of adiponectin, leptin, and IL-6 were estimated using multivariable conditional logistic regression models. RESULTS: Body mass index was not associated with either incident prostate cancer [obese versus normal; OR, 0.75; 95% confidence interval (95% CI), 0.38-1.48; P(trend) = 0.27] or high-grade versus low-grade disease (OR, 1.17; 95% CI, 0.39-3.52; P(trend) = 0.62). Moreover, none of the three adipokines was statistically significant associated with prostate cancer risk or high-grade disease, respectively: leptin (highest versus lowest tertile; OR, 0.77; 95% CI, 0.28-1.37; P(trend) = 0.57; OR, 1.20; 95% CI, 0.48-3.01; P(trend) = 0.85); adiponectin (OR, 0.87; 95% CI, 0.46-1.65; P(trend) = 0.24; OR, 1.93; 95% CI, 0.74-5.10; P(trend) = 0.85); IL-6 (OR, 0.84; 95% CI, 0.46-1.53; P(trend) = 0.98; OR, 0.84; 95% CI, 0.30-2.33; P(trend) = 0.17). CONCLUSIONS: Findings from this nested case-control study of men routinely screened for prostate cancer and who had a high prevalence of overweight and obesity do not provide evidence to support that prediagnostic obesity or factors elaborated by fat cells strongly influence prostate cancer risk or aggressiveness. However, due to the small sample population, a small or modest effect of obesity and adipokines on these outcomes cannot be excluded.