Genetic Mysteries of Breast Cancer

(Ivanhoe Newswire) -- New research is helping doctors unlock the genetic mysteries behind breast cancer, helping women discover and treat their disease earlier.

Nearly 200,000 women learn they have breast cancer each year. Doctors estimate between five percent and 10 percent of these women have a hereditary form of the disease caused by genetic mutations, but not all of these genetic mutations have been identified. The most understood -- BRCA1 and BRCA2 gene mutations -- can lead to breast cancer in up to 80 percent of carriers. However, there are many patients who have a clear genetic risk, but are not carriers of BRCA genetic mutations.

Researchers followed nearly 1,500 women in 365 families who tested negative for BRCA gene mutations, but had two or more cases of breast cancer in close relatives under the age of 50, or three or more cases among close relatives of any age. They discovered a 4.3-fold increase in their breast cancer occurrence compared to average rates in their area.

“Now when we see families such as this, we will be able to offer better advice about their actual risk. It is clear to me that the risk is high enough that we need to discuss options such as breast MRI for screening and chemoprevention with tamoxifen or raloxifene,” Steven Narod, M.D., the study’s senior author who holds the Canada Research Chair in breast cancer at the University of Toronto and Women’s College Research Institute, was quoted as saying.

Dr. Narod also said following these women closely will help evaluate the best methods of prevention.

SOURCE: Presented at the American Association for Cancer Research’s Seventh Annual International Frontiers in Cancer Prevention Research in National Harbor, MD, November 18, 2008