Obesity is a cancer risk factor. While it does not increase the risk of localized prostate cancer, it raises the risk of the aggressive disease in men of European ancestry. Few studies investigated obesity as a prostate cancer risk factor in men of African ancestry. Findings from those studies were heterogeneous but some reported an association of excess body fatness with aggressive disease.
We examined the relationship of body mass index (BMI), waist circumference, and waist-hip ratio with prostate cancer in African-American and European-American men in the NCI-Maryland Prostate Cancer Case-Control study consisting of 798 men with incident prostate cancer (402 African-American and 496 European-American) and 1008 population-based controls (474 African-American and 534 European-American). BMI was self-reported. Waist circumference and waist-hip ratio were calculated from measurements at enrollment.
A high BMI either at enrollment or years prior to it was associated with a decreased risk of prostate cancer in African-American men. In contrast, an elevated BMI tended to increase the disease risk in European-American men. Waist circumference was inversely associated with prostate cancer in both African-American and European-American men whereas a high waist-hip ratio did not associate with prostate cancer in African-American men but tended to be associated with advanced/aggressive disease in European-American men.
Our findings reveal an obesity paradox among African-American men in this study population, where a high BMI and waist circumference associated with a decreased disease risk.
Our observations expand the knowledge of how obesity may affect prostate cancer risks in African-Americans.
Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2018 May 21 [Epub ahead of print]
Margaret S Pichardo, Cheryl J Smith, Tiffany H Dorsey, Christopher A Loffredo, Stefan Ambs
Laboratory of Human Carcinogenesis, National Cancer Institute., Lombardi Comprehensive Cancer Center, Georgetown University., Laboratory of Human Carcinogenesis, National Cancer Institute .