More genes show possible link to breast cancer risk

Scientists reported Sunday that they had discovered several additional genes that might contribute to the risk of getting breast cancer – discoveries that, if confirmed, could someday lead to better screening tests and treatments.

Breast cancer risk is in part inherited, but the genes responsible are largely unknown. Rare mutations in two genes, BRCA1 and BRCA2, account for less than half of the inherited part of breast cancer prevalence.

Many scientists suspect the remaining parts are spread among scores of other genetic mutations that are probably much more common than BRCA1 and BRCA2 but individually contribute a much smaller degree of risk. That makes them more difficult to find, because many people who have them will not get cancer.

In one of the new studies, researchers at Harvard University and the National Cancer Institute used blood samples to compare the genetic makeup of about 3,000 women with breast cancer against about 3,000 healthy counterparts.

Of more than half a million mutations – or “gene variants” – studied, one in particular, called FGFR2, appeared to contribute significantly to breast cancer risk. It is notable because the risky variant exists in up to 60 percent of women of European descent and can increase risk by 20 percent to 60 percent compared with women with the safer variant, the team reported in Sunday’s online edition of the journal Nature.

BRCA1/2 raises breast cancer risk by about 900 percent.

Related research in Sunday’s online edition of Nature Genetics offers evidence for contributions from a handful of other genes as well. But researchers said it is too soon to think about testing women for the genes because the results are still preliminary, and, to be meaningful, any test would have to include a combination of many of the low-risk genes.