Wednesday, March 26, 2014
Cancer genetics experts say the discovery of the BRCA gene mutations has transformed the way doctors prevent and treat hereditary cancers. Read the post and watch the video.
“About 20 years ago, there was much debate about the ethical and clinical implications of identifying a gene mutation linked to cancer risk,” said Kenneth Offit, Director of the Clinical Genetics Service at Memorial Sloan Kettering, at a CancerSmart discussion on hereditary cancers and genetics.
Dr. Offit explained that before the discovery of the BRCA gene mutations, which increase the risk of breast cancer and some other cancers, doctors were already performing preventive breast surgery in women with a strong family history of the disease.
“The paradox is that we are actually doing fewer preventive breast surgeries now because people who thought they were at risk for breast cancer learned they did not have the gene mutation,” he added.
Most cancers are caused by spontaneous changes, called mutations, in genes. Gene mutations that are passed down through families (inherited) can lead to what are referred to as hereditary forms of cancer. BRCA gene mutations, which include mutations in the BRCA1 and BRCA2 genes, were the first to be associated with hereditary cancers. In addition to breast cancer, they are linked to familial ovarian, prostate, and pancreatic cancers.
Who Should Consider Genetic Testing
According to breast surgeon Alexandra Heerdt, there is a fundamental difference between hereditary breast cancer, in which multiple genes place a woman at increased risk for the disease, and breast cancer caused by a BRCA mutation. In fact, while a significant number of women with breast cancer have a family history of the disease, fewer than one in ten of these are considered cases of hereditary breast cancer — and only a subgroup of the hereditary cases are caused by a BRCA mutation. BRCA mutations are more common in people from certain ethnic groups, such as Ashkenazi Jews of Eastern European descent.
Genetic counselors look for red flags, such as having had several relatives diagnosed with breast cancer at an early age, to determine if genetic testing is appropriate, said Memorial Sloan Kettering genetic counselor Emily Glogowski.
Genetic testing involves analyzing tissue from a blood test or a cheek swab to look for mutations in a person’s DNA. Because of the complex decisions that may stem from learning about one’s genetic profile, experts recommend that most people wait until age 20 to 25 before getting tested for BRCA1 and BRCA2 mutations. “Determining whether testing should be done, or what tests should be ordered, is a very individualized process,” explained Ms. Glogowski.Back to top
Cancer Prevention in Women with a BRCA Mutation
Surgery to remove the ovaries is recommended for women who have a BRCA mutation, as there is no consistently reliable or accurate way to screen for ovarian cancer (especially for early-stage disease).
Depending on a woman’s family history of breast cancer and the type of mutation she has, doctors may prescribe regular breast screening with MRI or chemoprevention with estrogen-blocking drugs such as tamoxifen. Preventive breast surgery (mastectomy) is another option for women with a family history of breast cancer and a BRCA mutation. “Your family’s experience with cancer figures dramatically into the decision about whether or not to have preventive surgery,” Dr. Heerdt said.
The panelists observed that Memorial Sloan Kettering’s collaborative approach helps patients navigate a variety of difficult decisions while giving them access to the latest prevention and treatment strategies.Back to top