(HealthDay)—Researchers report that they've identified another genetic variation that appears connected to male breast cancer, a rare condition that kills several hundred men in the United States each year.
The finding won't immediately lead to any improvements in treatment for the disease. Still, "by finding more male breast cancer genes, we can understand more about the biology of the disease and, as a result, get a better understanding of how best to treat male breast cancer," said study author Dr. Nick Orr, a team leader at the Institute of Cancer Research in London. "We hope these findings will also help us to learn more about how the disease works in women, too."
Male breast cancer is about 100 times less common than female breast cancer, according to the American Cancer Society. It estimates that this year breast cancer will be diagnosed in about 2,190 men in the United States and will kill about 410 men.
The prognosis for men with breast cancer is similar to that for women with breast cancer, although less is known about the disease in men. A study released last year also found that men are diagnosed on average at an older age (70) than women (62).
"We've made a lot of progress in finding causes of breast cancer in women over the past couple of decades," Orr explained. "But we know very little about what causes the disease in men."
In the new study, researchers examined the DNA of 823 men with breast cancer and 2,795 similar men without the disease. They then attempted to validate their results by looking at the genes of 438 men with the disease and 474 similar men without it.
Orr said his team found that a variation in a gene known as RAD51B was found in 20 percent of the men with breast cancer, but only 15 percent of those without it. The variation has also been linked to female breast cancer.
The findings add to previous research that has linked mutations in a gene known as BRCA2 to a higher rate of breast cancer in men. Mutations in the gene greatly boost the risk of breast cancer in women.
For now, the findings are useful in terms of understanding the disease, said Dr. Mikael Hartman, an assistant professor at National University of Singapore. "The ultimate goal is prevention, but that is a long way ahead. Thus, any preventive treatment will have to wait."
While it's helpful to know which genes are connected to the disease, he said, "the ability of these markers to predict breast cancer is so far only marginally better than flipping a coin. When hopefully hundreds of these markers are identified, we could consider making predictions based on an individual's genetic makeup."
The study is published online Sept. 23 in the journal Nature Genetics.
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More information: For more about male breast cancer, see the U.S. National Library of Medicine.
Paper: DOI: 10.1038/ng.2417