Joining FORCES is the FORCE newsletter with news, views and supportive information for individuals concerned about hereditary breast and ovarian cancer.
by Amber Iwan and Sue Friedman
Presenters: Jennie Yoon, MD and Victoria Seewaldt, MD
Radiologist Dr. Yoon outlined standard-of-care guidelines developed by NCCN — a consortium of experts from top centers — for breast surveillance in BRCA mutation carriers:
Because mutation carriers tend to develop breast cancers at a younger age than women without mutations, they should begin screening at a young age. But breast screening has risks and limitations. While mammography is not ideal for screening the dense breasts of young women, it is good at finding microcalcifications — small calcium deposits that may indicate earlystage cancer. The radiation dose from annual mammograms is small, but some scientists are concerned about repeated exposure in young mutation carriers who may be more sensitive to radiation. The utility of mammography for early detection of triple-negative breast cancer (the type most frequently developed by BRCA1 mutation carriers) is uncertain; only 15% of these cancers form calcifications. Breast Magnetic Resonance Imaging (MRI) is more sensitive for screening triple-negative breast cancer. Although it does not expose patients to radiation, MRI more often finds abnormalities — both cancer and harmless changes — that require a biopsy.
Researchers are studying new technologies to improve high-risk surveillance. "Microdose" mammography reduces radiation exposure. Tomosynthesis, a type of three-dimensional mammogram, improves visualization of abnormalities over traditional two-dimensional mammograms. Three-dimensional breast ultrasound may find abnormalities without subjecting patients to radiation. Two other surveillance technologies, breast specific gamma imaging (BSGI) and positron emission mammography (PEM), more accurately image dense breasts, although both expose patients to additional radiation. PEM has also been used to follow response to cancer treatment.
NCCN gidelines include other risk-management options, such as chemoprevention (medications that lower the risk for cancer), riskreducing salpingo-oophorectomy (removal of the ovaries and tubes, which lowers the risk for breast and ovarian cancers) and prophylactic mastectomy.
Dr. Seewaldt discussed tamoxifen and raloxifene, currently the only FDA-approved breast cancer chemoprevention options. Both drugs work by blocking hormones in the body. Only tamoxifen is approved for premenopausal women; some evidence suggests that it may prevent breast cancer in women with BRCA2 mutations, but it may not have the same protective benefit for carriers of BRCA1 mutations. PARP inhibitors are a new class of drugs being tested in people with hereditary cancers. Currently there are safety concerns regarding the use of PARP inhibitors in previvors without cancer. More research is needed before PARP inhibitors can be considered for prevention. Metformin, a drug approved for treating type II diabetes, is being studied for preventing breast cancer. It affects cellular pathways that might lead to cancer, especially in people with BRCA1 mutations. Metformin's safety has already been established from use in diabetics; it also appears to be safe for people without diabetes. Its mechanism for cancer prevention may be similar to the effect of exercise, which lowers breast cancer risk in high-risk women. Dr. Seewaldt will lead a breast cancer prevention study of Metformin later this year. Check the FORCE Featured Research webpage for updates.
Amber is a self-described "lab rat" who lives in Minneapolis with her husband and two dogs. She inherited a BRCA1 mutation from her mother, who successfully completed treatment for breast cancer at the age of 49. In her spare time, Amber works on a modern fiction novel with a BRCA-positive protagonist.