A nationwide study of more than 1,000 women with breast cancer has wide ranging implications for all women who carry either of two gene mutations linked to breast and ovarian cancer. Specifically, researchers discovered women who have the BRCA1 or BRCA2 gene mutation have a 20% chance of developing breast cancer by age 40, a 55% chance by age 60, and more than an 80% chance by age 80. That's compared to just a 10% lifetime risk for women without the gene mutations.
"We found two things in our study. That the risk of breast and ovarian cancer associated with the mutations in BRAC1 and 2 are very high and there are lifestyle factors in one's young life that are protective," says Mary Clair King, University of Washington.
The study found that even though women can't get rid of that gene, they can at least help postpone their cancer risk by exercising and maintaining a healthy weight during their teenage years. The study also found that family history isn't always an obvious clue since a woman can inherit the gene mutations from their father.
Researchers say they hope these findings will help doctors and their patients make informed decisions to prevent or reduce their risks.
The BRCA1 and 2 gene mutations occur in about 10% of women. Researchers say when a woman is born, it also plays a role in her risk. Women born before 1940 had a 24% chance of developing breast cancer by age 50; women born after 1940 had a nearly 70% chance, suggesting environmental factors play a role.
Previous studies had suggested widely varying estimates of breast cancer risk ranging from 25% to 80% - among women with BRCA1 and BRCA2 mutations. The study was conducted by the New York Breast Cancer Study Group and is in the October 24 edition of Science.
The New York Breast Cancer Study Group includes Dr. King, other University of Washington researchers, and co-authors Joan H. Marks and Jessica B. Mandell of the Sarah Lawrence College graduate program in human genetics. The study team also included physicians, surgeons, and genetic counselors from Albert Einstein College of Medicine/Montefiore Medical Center; Beth Israel Medical Center; Columbia Presbyterian Medical Center, Columbia University; Englewood Hospital and Medical Center; Greenwich Hospital, Yale Cancer Center; Hackensack University Medical Center; Memorial Sloan-Kettering Cancer Center; New York University Medical Center; North Shore University Hospital; Sarah Lawrence College; Stamford Hospital, Bennett Cancer Center; Strang Cancer Prevention Center; White Plains Hospital Center; and private practitioners.
More than 100 genetics counseling graduate students also worked on the project.