Study should encourage physicians to take note of findings
Blacks have a higher risk of developing prostate cancer than whites; for obese black men, that risk can quadruple as their weight increases, a recent study finds.
Roughly six in 10 prostate cancer cases occur in men older than 65, according to the American Cancer Society. For unknown reasons, it has long been known that black men, at any age, face a greater overall risk for the disease than men of other races. They also have the highest risk for aggressive prostate cancer and death.
This study, led by Wendy Barrington, an assistant professor in the school of nursing at the University of Washington, was designed to explore a possible connection between obesity and prostate cancer. Investigators analyzed data collected from nearly 3,400 black men and almost 22,700 white men between 2001 and 2011 as part of the Selenium and Vitamin E Cancer Prevention Trial. All of the men, age 55 and older, were cancer-free at the start of the trial.
During a five-year follow-up period, 270 black men and 1,453 white men in the study developed prostate cancer. Overall, there was 58 percent increased risk for prostate cancer among black men compared with white men. And obese black men had an even greater increase in risk. Very obese black men, those with a body mass index (BMI) of 35 or greater, had a 103 percent increased prostate cancer risk compared to white men in the same weight group.
The study also found that severely obese black men had a 122 percent increased risk for low-grade (slow-moving) prostate cancer. Their risk for high-grade (fast-moving) disease was 81 percent higher. Obese white men, meanwhile, had a 33 percent higher risk for aggressive prostate cancer compared with normal-weight whites, and no greater risk for the slow-growing form.
“We did account for many differences that could affect prostate cancer risk, such as access to care, and lifestyle factors, such as diet and physical activity,” Barrington said.
Being overweight or obese has been linked to a higher risk of some other types of cancer, including colon, esophagus, kidney and pancreatic cancers, but experts say this study established only an association between race, obesity and prostate cancer, not a direct cause-and-effect relationship. Barrington said the findings should lead to a redoubling of efforts to encourage obesity prevention among black men. The study’s results should also strengthen calls for routine prostate cancer screening in high-risk populations, which now includes obese men of African descent.
“The main ‘take-home’ point for practicing physicians is to recognize that obesity has a different relationship to prostate cancer risk in African-American [men] compared to non-Hispanic white men,” Barrington said. So the reasons for the disparity could “really just speculation at this point. it could be that there’s actually a biological difference between African-American and non-Hispanic white men.”