CASE
Using the assessment results, the clinician talks to Ms. P about her lifetime risk for breast cancer. The Gail model indicates her lifetime risk is 13.3%, just slightly higher than the average (12.5%), and her 5-year risk is 0.5% (average, 0.4%). The IBIS or Tyrer-Cuzick model, which takes into account her second-degree relatives with breast and ovarian cancer and her Ashkenazi ethnicity (which confers increased risk due to elevated risk of BRCA mutations), predicts her lifetime risk of breast cancer to be 20.4%. This categorizes Ms. P as high risk.
Enhanced screening recommendations for women at high risk
TABLE 48,13,22 summarizes screening recommendations for women deemed to be at high risk for breast cancer. The American Cancer Society (ACS), NCCN, and the American College of Radiology (ACR) recommend that women with at least a 20% lifetime risk have yearly magnetic resonance imaging (MRI) and mammography (staggered so that the patient has 1 test every 6 months) starting 10 years before the age of onset for the youngest affected relative but not before age 30.8 For carriers of high-risk (as well as intermediate-risk) genes, NCCN recommends annual MRI screening starting at age 40.13BRCA1/2 screening includes annual MRI starting at age 25 and annual mammography every 6 months starting at age 30.22 Clinicians should counsel women with moderate risk factors (elevated breast density; personal history of ADH, LCIS, or DCIS) about the potential risks and benefits of enhanced screening and chemoprophylaxis.
Risk-reduction strategies
Chemoprophylaxis
The US Preventive Services Task Force (USPSTF) recommends that all women at increased risk for breast cancer consider chemoprophylaxis (B recommendation)23 based on convincing evidence that 5 years of treatment with either a synthetic estrogen reuptake modulator (SERM) or an aromatase inhibitor (AI) decreases the incidence of estrogen receptor positive breast cancers. (See TABLE 57,23,24 for absolute risk reduction.) There is no benefit for chemoprophylaxis in women at average risk (D recommendation).23 It is unclear whether chemoprophylaxis is indicated in women with moderate increased risk (ie, who do not meet the 20% lifetime risk criteria). Chemoprophylaxis may not be effective in women with BRCA1 mutations, as they often develop triple-negative breast cancers.
Accurate risk assessment and shared decision-making enable the clinician and patient to discuss the potential risks and benefits of chemoprophylaxis.7,24 The USPSTF did not find that any 1 risk prediction tool was better than another to identify women who should be counseled about chemoprophylaxis. Clinicians should counsel all women taking AIs about optimizing bone health with adequate calcium and vitamin D intake and routine bone density tests.
Surgical risk reduction
The NCCN guidelines state that risk-reducing bilateral mastectomy is reserved for individuals with high-risk gene variants and individuals with prior chest radiation between ages 10 and 30.25 NCCN also recommends discussing risk-reducing mastectomy with all women with BRCA mutations.22
Bilateral mastectomy is the most effective method to reduce breast cancer risk and should be discussed after age 25 in women with BRCA mutations and at least 8 years after chest radiation is completed.26 There is a reduction in breast cancer incidence of 90%.25 Breast imaging for screening (mammography or MRI) is not indicated after risk-reducing mastectomy. However, clinical breast examinations of the surgical site are important, because there is a small risk of developing breast cancer in that area.26
Risk-reducing oophorectomy is the standard of care for women with BRCA mutations to reduce the risk of ovarian cancer. It can also reduce the risk of breast cancer in women with BRCA mutations.27
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