Researchers have identified a rare genetic mutation that appears to significantly increase men's risk of prostate cancer.
Men who have the mutation are 10 to 20 times more likely to develop prostate cancer than those without the mutation, the researchers said. In particular, the mutation increases the risk of hereditary and early onset prostate cancer.
The findings mark the first time an inherited gene mutation has been found that confers such a high risk for prostate cancer, said study researcher Dr. Kathleen Cooney, professor of internal medicine and urology at the University of Michigan Medical School. It is also one of the first genetic markers to be identified for early-onset prostate cancer.
The mutation, found in a gene called HOXB13, is quite rare: only about 1 percent of men with prostate cancer have it.
While much more research is needed, there is a possibility that men with a family history of prostate cancer may one day undergo genetic screening for this mutation, said study researcher William Isaacs, professor of urology and oncology at the Johns Hopkins University School of Medicine. Such screening would be similar to the tests given to women with a family history of breast cancer, who are screened for mutations in the breast cancer susceptibility genes known as BRCA1 and BRCA2.
More studies on larger groups of men are needed to confirm exactly how common this mutation is, and how much risk it conveys, Isaacs said. Future studies may identify additional genetic mutations that influence prostate cancer risk.
"This might be potentially the tip of the iceberg," Isaacs said.
Prostate cancer in families
The study included 94 men whose families had a history of prostate cancer (for instance, both father and son had prostate cancer.) Researchers sequenced 200 of the men's genes, all from a region of the genome suspected to be linked with prostate cancer.
The researchers identified four men with the same mutation in the HOXB13 gene. When their relatives were tested, all 18 men with prostate cancer in these four families were found to have the mutation.
Next, the researchers looked to see how common this mutation was in a second group of 5,100 men with prostate cancer. About 1.4 percent, or 72 men, in this group had the mutation.
Among men who had a family history of the disease and who developed prostate cancer before age 55, 3.1 percent had the mutation, whereas 0.6 percent of men without a family history who developed prostate cancer later in life had it.
Among men without prostate cancer, the chances of having this mutation were lower, about 0.1 percent.
The finding is an "important discovery," and may provide insight into the factors that drive prostate cancer, said Dr. Manish Vira, of the Arthur Smith Institute for Urology, part of the North Shore-Long Island Jewish Health System in New Hyde Park, N.Y. "Hopefully, further work with this particular gene will improve our understanding of how prostate cancer develops," Vira said.
It's not clear how the mutation leads to cancer, but the HOXB13 gene is thought to play a role in the development of the prostate gland, Cooney said.
The mutation was found only in families of European descent. More research is needed to determine mutations that may influence the risk of prostate cancer in other ethnic groups.
The study is published in the Jan. 12 issue of the New England Journal of Medicine.
Pass it on: A rare genetic mutation may increase the risk of inherited prostate cancer.