Researchers at Huntsman Cancer Institute at the University of Utah in Salt Lake City added four new genes to the list of those known to cause increased breast cancer risk. The findings are the result of an international consortium working to discover gene mutations that cause inherited breast cancer susceptibilities.
BRCA1 and BRCA2 arent the whole story when it comes to inherited breast cancer risk, Sean Tavtigian, PhD, an HCI investigator, professor in the Department of Oncological Sciences at the University of Utah and one of three joint-principal investigators on the study, said in a news release. Weve known for a long time that more genes had to be responsible and several have since been discovered, by us and by others. Originally, the gene we are currently studying, called RINT1, was not considered a human cancer susceptibility gene. But then we discovered there was a two- to three-fold increase in risk for breast cancer in families that carry a mutation in that gene.
The RINT1 findings were published this month in the journal Cancer Discovery.
RINT1 also was found to increase risk for a broad spectrum of gastrointestinal and gynecological cancers in these families. Many genes responsible for a strong increase in cancer risk at one or two sites in the body also are connected with lesser increases in risk at other sites, said David Goldgar, PhD, professor in the Department of Dermatology at the U of U, an HCI investigator, and another of the studys joint-principal investigators. However, with RINT1 mutations, the increased risk for other cancers is about equal to that for breast cancer.
In another study led by Tavtigian, mutations in three other genes MRE11A, RAD50 and NBN also were confirmed to increase breast cancer risk, as reported in the journal Breast Cancer Research June 3. The proteins encoded by these three genes form a tight complex that is involved in DNA repair, and the three genes had been considered likely candidates, said Tavtigian. But we dont know yet if that biochemical connection explains RINT1s cancer susceptibility role.
Now almost 50% of the familial risk for breast cancer can be explained by the ensemble of rare mutations in known breast cancer susceptibility genes and more common genetic variation in about 75 areas of the genome each of which is associated with only a small increased risk of breast cancer, according to Goldgar, compared to about 30% only five years ago.