Renal cell cancer and body size at different ages: an Italian multicenter case-control study.

An increased risk of renal cell cancer (RCC) has been reported in overweight persons. The authors aimed to clarify which anthropometric measures are associated with risk of RCC and whether risk may vary according to selected variables. Between 1992 and 2004, they carried out an Italian multicenter case-control study including 767 (494 men, 273 women) incident cases of RCC and 1,534 hospital controls, frequency-matched to cases. To estimate odds ratios and 95% confidence intervals, they used conditional logistic regression matched on study center, sex, and age and adjusted for period of interview, years of education, smoking habits, and family history of kidney cancer. Using body-size measurements taken 1 year prior to diagnosis/interview, the authors found an odds ratio of 1.3 (95% confidence interval (CI): 1.0, 1.7) among obese persons (body mass index (BMI; weight (kg)/height (m)(2)) > or =30) versus normal-weight persons (BMI <25) and an odds ratio of 1.5 (95% CI: 1.1, 2.0) among persons in the highest tertile of waist-to-hip ratio. Direct associations emerged for BMI > or =30 (vs. <25) at ages 30 years (odds ratio = 1.5, 95% CI: 1.0, 2.3) and 50 years (odds ratio = 1.5, 95% CI: 1.1, 2.0). The direct association with waist-to-hip ratio was stronger among women than among men. RCC risks among overweight and obese persons were apparently higher in never smokers, persons with the clear-cell histologic type, and persons with a Fuhrman nuclear grade of G3-G4.