Reducing the risk of breast cancer: A personalized approach
Although primary care physicians often use the same screening schedule and preventive measures for all the women they see, optimal breast cancer risk reduction requires an individualized approach.
Imaging strategies for those at risk
Although there is evidence that mammography performed on postmenopausal women can reduce breast cancer mortality by 25%, there are known limitations to this detection method.14
One drawback is that in premenopausal women, breast density lowers mammography’s sensitivity. In addition, several studies have found that mammography has a low sensitivity for detecting tumors in patients with a BRCA mutation. This has led to the use of other imaging modalities, especially MRI, for women with a family history that suggests a genetic predisposition.
The first study to demonstrate the superior sensitivity of MRI for detecting invasive breast cancer compared with clinical breast exam and mammography was published in 2004.35 A few years later, the ACS issued guidelines that call for surveillance with MRI as an adjunct to mammography, starting at age 30, for women whose family history, carrier status, or history of chest wall radiation puts them at very high risk (ie, a lifetime risk >20%-25%).14
The ACS found insufficient evidence to recommend for or against breast MRI for women with a lifetime risk of 15% to 20% (or documented high-risk lesions such as lobular carcinoma in situ, ALH, or ADH). Mammographic density, which in itself is a strong risk factor for the development of breast cancer, was not determined to be an indication for MRI screening. In deciding whether MRI is indicated for any high-risk patient, the cost, quality of imaging, and lower specificity must be considered.14
Weighing the benefits of surgery
For women who have a strong family history of breast cancer or are known carriers of a BRCA1 or BRCA gene mutation, the already high risk of developing breast cancer increases as they age. Prophylactic surgery—risk-reduction mastectomy (RRM) and/or bilateral salpingo-oophorectomy (RRSO)—has been found to lower the risk.5,36,37
RRM can reduce the risk of breast cancer by as much as 90% for such patients;38,39 RRSO yields similar results, reducing the risk of ovarian cancer by 80% to 95% and the risk of breast cancer by 40% to 59%, provided the surgery is performed before the patient is 40 years old.36,37
These potential benefits must be weighed against the harm associated with surgically induced menopause, with the attendant risks of cardiovascular disease, osteoporosis, and menopausal symptoms.40 Notably, hormone therapy use after RRSO in women with a gene mutation has not been found to increase the risk of breast cancer. In fact, it may be associated with a decreased risk.5 In general, short-term use of low-dose estrogen—up to the age of 51 or 52 years—is considered to be safe for this population,41,42 but long-term data on breast cancer risk are lacking.
CORRESPONDENCE
Marcia G. Ko, MD, Mayo Clinic, 13737 North 92nd Street, Scottsdale, AZ 85369; ko.marcia@mayo.edu
