Dec. 12 (UPI) -- Black men are more likely than white men to develop hormone receptor positive, or HR+, breast cancer, even though the opposite is the case for women with the disease, a new analysis has revealed.
In research supported by the American Cancer Society and published Thursday in the journal INCI Cancer Spectrum, rates for all subtypes of breast cancer were higher among black men than white men. Prevalence of HR+/HER- breast cancer, for example, was found to be approximately 41 percent higher among black men, while rates of HR+/HER2+ cancer were 65 percent higher.
HER refers to human epidermal growth factor receptor, a protein involved in breast cancer. The ACS noted that this is the first report on differences in subtype-specific breast cancer incidence rates between black men and white men.
"Difference in cancer risk according to populations suggests that there are variations in the prevalence of risk factors," study co-author Hyuna Sung, a cancer epidemiologist and principal scientist at the American Cancer Society, told UPI. "For male breast cancers, unfortunately we don't know much about risk factors. More research is needed to identify causes of male breast cancer so we can explain the racial disparity we observed and potentially inform targeted prevention strategies."
Less than 3,000 men in the U.S. are diagnosed with breast cancer annually, and males make up roughly 1 percent of the total cases of the disease nationally. In general, risk factors for breast cancer among men include family history of the disease; mutations in the BRCA2 gene, a gene known to be involved in the disease; radiation exposure; and conditions that alter hormonal balance, such as Klinefelter syndrome and gynecomastia.
According to Sung, being obese and having diabetes may also be risk factors for the disease among men. In addition, earlier research has suggested that higher levels of estradiol, a hormone, may increase risk for male breast cancer.
For their study, Sung and the ACS team used nationwide data on breast cancer and reviewed cases according to subtype. In addition to the numbers cited above, they found that rates for HR-/HER2+ and triple-negative breast cancer were 2.5 and 2.27 times higher, respectively, in black men than in white men.
Conversely, they noted, rates in black women were 21 percent lower for HR+/HER2- and comparable for HR+/HER2+, but 29 percent and 93 percent higher for HR-/HER2+ and triple-negative subtypes, respectively. Racial differences in the prevalence of mammography and menopausal hormone supplements are thought to have contributed to the historically higher rates of HR+ cancers in white women, but these are not factors in breast cancer in men, according to the ACS.
Breast cancer in men isn't often talked about, due in large part to the fact it remains relatively rare. There is also a bit of a stigma surrounding it, given that it is often seen as a "women's disease."
Of course, this stigma has no effect on prevalence or cancer risk, though, Sung noted, "hesitance to get an exam when they felt any relevant symptom or lack of awareness in general may have prevented some men from detecting the cancer earlier."