A nationwide study led by researchers at the University of Washington and Fred Hutchinson Cancer Research Center in Seattle recently revealed that obese African American men have an increased risk for prostate cancer development. The study was published in the journal JAMA Oncology and is entitled “Difference in Association of Obesity With Prostate Cancer Risk Between US African American and Non-Hispanic White Men in the Selenium and Vitamin E Cancer Prevention Trial (SELECT).”
According to the National Cancer Institute, African American men have the highest incidence of prostate cancer than any other racial or ethnic group in the United States, and their cancers tend to be more aggressive, inducing higher mortality rates in comparison to non-Hispanic white men. The reasons behind this phenomenon are not clear, although it is thought that it might be linked to environmental and genetic factors. Since obesity, which is influenced by both social and biological factors, has been reported to be more prevalent among African Americans, the research team hypothesized that it could have an impact in prostate cancer risk in this specific racial group.
“Given that obesity is more common among African-Americans, [the prostate cancer-obesity connection] is an important question to study, as it may shed light on how to reduce black/white disparities in prostate cancer incidence,” said the study’s lead author Dr. Wendy Barrington in a news release.
A prospective study was conducted to assess how ethnicity and obesity affect prostate cancer risk and to better understand the so-called “African-American race effect” on the differences observed in this type of cancer. In total, data of 3,398 African Americans and 22,673 non-Hispanic white men enrolled in the Selenium and Vitamin E Cancer Prevention Trial (SELECT study, 2001-2011) were collected and analyzed.
Researchers found that African American men who are obese (with a body mass index of 35 or higher) had an 122% increase in the risk for low-grade prostate cancer and 81% increase in the risk for developing high-grade prostate cancer in comparison to individuals with normal weight (body mass index of 25 or lower). Remarkably, on the other hand, obese non-Hispanic white man were found to have a 20% reduction in the risk of low-grade prostate cancer and a 33% increase in the risk of developing high-grade prostate cancer in comparison to non-Hispanic white man with normal weight.
The research team concluded that obesity has a different impact on prostate cancer risk depending on the individual’s ethnicity. “For unknown reasons, African-American men have a much higher risk of prostate cancer than non-Hispanic white men. Different effects of obesity might explain at least some of the difference in risk and, more importantly, preventing obesity in African-American men could substantially lower their prostate cancer risk,” said the study’s senior author Dr. Alan Kristal.
The reasons underlying this disparity are unknown. “There is some evidence that the biological responses to obesity, such as inflammation and glucose tolerance, are more pronounced in African-American men; both inflammation and insulin may promote cancer development,” explained Dr. Kristal. “This is the next question for researchers to ask, because the answer will likely tell something very important about prostate cancer development and prevention.” It has also been speculated that obesity could interfere with genes that control prostate cancer development.
This study reinforces the importance of preventing obesity. “Obesity prevention and treatment should be a priority for all Americans, but in particular for African-American men,” concluded Dr. Barrington. “Prostate cancer kills 45 out of 100,000 African-Americans and only 19 out of 100,000 white men, and obesity is contributing to this important health disparity. Health care providers need to consider obesity prevention for their African-American male patients as a targeted strategy to reduce prostate cancer disparities.”