Options for patients at increased risk for breast cancer
Any patient who is determined to be at increased risk for breast cancer should be offered the following options for early detection and risk reduction, as summarized in Figure 2.
Intensive surveillance
Intensive surveillance generally represents the mainstay for patients at increased lifetime risk of breast cancer. The goal of intensive surveillance is to detect breast cancer at earlier, treatable stages. Mammography represents the standard of care for breast imaging and decreases the risk of breast cancer by 40% for those at average risk with annual use beginning at age 40.15 Breast MRI carries higher sensitivity, with 1 randomized controlled trial of those at high risk for breast cancer due to family history demonstrating that more breast cancers were identified with MRI compared with mammography, were smaller in size, and were less likely to have positive lymph nodes.16 Therefore, annual mammography plus annual supplemental breast MRI with and without contrast is recommended for high-risk patients. It is often clinically recommended that mammogram and MRI be staggered by 6 months, although there are no data suggesting improved cancer detection with this method. This screening is coupled with clinical breast exams every 6 to 12 months at the time of initiation of intensive surveillance, along with ongoing self-breast awareness.
While mammograms represent a rapid and largely accessible study, breast MRI may pose barriers for some patients. Breast MRI may be cost prohibitive for some and may not be available at all radiology centers. For patients with claustrophobia, breast MRI may induce anxiety and cause early termination of the study. Treatment with a one-time dose of a benzodiazepine taken 30 minutes before the MRI may help some patients. Allergies to gadolinium contrast could pose challenges, although some facilities may provide the option of a steroid prep (± diphenhydramine) for gadolinium intolerance. Due to comorbidities (such as morbid obesity, congestive heart failure, or severe pulmonary disease), patients may not be able to tolerate lying prone for extended periods of time. Patients should also be counseled on the higher risk of false positives that could lead to more breast biopsies. For patients who are unable to tolerate or undergo breast MRI, other options such as contrast-enhanced mammography or molecular breast imaging can be explored. Whereas breast ultrasound may also be considered, it does not have comparable sensitivity.
Age of initiation varies based on the reason for increased lifetime breast cancer risk. The recommendations based on high-risk category are outlined in Table 1 and Table 2. There are certain general age considerations regarding imaging. Breast MRI is generally not performed before age 25 (although with some exceptions) and mammogram is generally not performed before age 30. The question of when to discontinue breast screening often arises. While there are no clearly defined guidelines, age 75 is a time at which to consider a risk-benefit discussion. If a patient is overall healthy with a life expectancy of 10 or more years, it is reasonable to continue intensive screening. However, if a patient has medical comorbidities in which life expectancy is not projected to exceed 10 years, shared decision-making should be employed to determine if the patient is capable of continuing screening, and whether they would accept intervention if there were a suspicious finding.
There are certain considerations for high-risk screening during pregnancy and lactation. Breast MRI should be deferred during pregnancy or if the patient is actively trying to conceive. The gadolinium-based contrast used in breast MRI crosses the placenta and can result in fetal exposure and gadolinium retention. Although some small retrospective studies show no adverse effects, animal studies have demonstrated some fetal malformations and demise after supra-clinical doses.17,18 Despite the data being limited and inconclusive, MRI should be avoided due to the potential teratogenicity. Mammography, however, is considered safe in pregnancy and delivers fetal doses of 0.03 mGy, for which the fetal dose is negligible.19 During lactation, both mammogram and breast MRI can be used, although the breast tissue is denser during this time which may limit sensitivity of breast imaging. Pumping or breast/chest feeding prior to imaging is recommended for both modalities to improve sensitivity, specificity, and patient comfort.
Chemoprevention
Tamoxifen is a selective estrogen receptor modulator (SERM) that is shown to reduce breast cancer risk by 49%.20 Whereas the standard dose is 20 mg daily for 5 years, low-dose tamoxifen (5 mg for 3-5 years) can be considered for patients unable to tolerate the higher dose.20,21 (Of note, because 5-mg dosage is not available in the United States, 10 mg every other day could be considered.) Although the benefit of tamoxifen in BRCA1/2 carriers is less well studied, limited data still suggest a possible benefit.22 Tamoxifen can be taken by both pre- and postmenopausal patients starting at age 35, although it should be avoided in those who wish to conceive or are pregnant due to the potential teratogenic effects. Despite the risk-reduction benefits, tamoxifen is associated with vasomotor symptoms, venous thromboembolism (VTE), stroke, cataracts, ovarian cysts, and vaginal discharge. Due to its partial estrogen agonist/antagonist effect on the endometrium, other adverse effects could include amenorrhea, abnormal bleeding patterns, endometrial proliferation including the spectrum of polyps, hyperplasia, invasive carcinoma, and uterine sarcoma (in postmenopausal patients).23
Raloxifene is a SERM that is approved for the treatment and prevention of osteoporosis in postmenopausal AFAB people. It is also used for breast cancer risk reduction after demonstrating effectiveness in the Study of Tamoxifen and Raloxifene (STAR) trial, for which the standard dosage was 60 mg daily for 5 years. Whereas results of the trial showed similar efficacy in decreased invasive breast cancer risk in both tamoxifen and raloxifene groups, raloxifene was not as effective in decreasing the risk of noninvasive breast cancer (ductal carcinoma in situ [DCIS]) or LCIS.24 Long-term data from the STAR trial demonstrates that raloxifene retains 76% of tamoxifen’s effectiveness in reducing the risk of invasive breast cancer in a median follow-up of 81 months.25 Raloxifene also carries a lower risk of VTE and cataracts, as well as a nonsignificant reduction in endometrial cancer. Therefore, while less efficacious regarding breast cancer risk reduction compared with tamoxifen, raloxifene has a more favorable adverse effect profile.
Both aromatase inhibitors (AIs)—exemestane (25 mg daily for 3 years) and anastrozole (1 mg daily for 5 years)—have been shown to reduce risk of breast cancer in large randomized trials by at least 53%.26 While both drugs are approved by the FDA for breast cancer treatment, neither are specifically labeled for preventive use by the FDA. Furthermore, there is little evidence demonstrating the effectiveness of AIs as chemoprevention for those with BRCA1/2 pathogenic variants.6 Adverse effects include vasomotor symptoms, diarrhea, and arthralgias, with no increased risk of VTE or endometrial cancer. Raloxifene and AIs should not be administered to premenopausal patients in this clinical context unless as part of a clinical trial.20
Risk-reducing mastectomy
Risk-reducing mastectomy decreases the risk of breast cancer by at least 90%.27 This option can generally be explored in patients who have a pathogenic/likely pathogenic high-penetrant breast cancer susceptibility gene (as outlined in Table 1), compelling family history, or those with a history of radiation therapy to the breast tissue prior to 30 years of age. There is no established risk benefit in those with pathogenic/likely pathogenic moderate- or low-penetrant genes, or those without a compelling family breast cancer history.20 One prior study suggests a potential mortality benefit to risk-reducing mastectomy in BRCA1/2 pathogenic/likely pathogenic mutation carriers.28 Another prospective analysis shows significant risk reduction in BRCA1/2 patients but that longer follow-up is required to determine true survival benefit.29 Results of one prospective study demonstrated a significantly reduced risk of breast cancer among BRCA1/2 gene mutation carriers (HR, 0.02) and reduced breast cancer-specific mortality (HR, 0.26), with a less than 1% probability of dying from breast cancer 15 years after mastectomy.30 However, much of the historical data on mastectomy in breast cancer survivors do not demonstrate a significant mortality benefit.31,32
Choice of risk-reducing mastectomy is a highly personal decision. For many patients, both the decreased risk of future breast cancer and the discontinuation of intensive surveillance can be primary motivating reasons. For many, the high sensitivity of breast MRI can lead to repeated biopsies (many representing false positives), which can be anxiety provoking and physically painful. For others, witnessing loved ones experience breast cancer could be another motivator to proceed with surgery.
However, there are other considerations. Surgical risk and the possible need for multiple surgeries to achieve aesthetic outcome should be acknowledged. The inability to subsequently breast/chestfeed may lead patients to delay risk-reducing mastectomy until after childbirth. For some, no longer undergoing intensive screening with mammogram and MRI can be stressful due to the very small but not impossible risk of breast cancer following risk-reducing mastectomy (for which the recommended surveillance post mastectomy is continued breast/chest wall awareness and annual clinical exam only). While some may be satisfied with their decision to proceed with mastectomy, others may experience regret.33 There are also multiple studies showing the possible physical and psychological impact of mastectomy on self-esteem, sexuality, and body appearance.34-36
It is important that practitioners share this information with patients during decision-making. Management should be individualized, and patients who wish to explore mastectomy should be referred to a breast surgical oncologist and plastic surgeon for a more in-depth discussion of surgical considerations and reconstruction options.
Conclusion
With the high prevalence of breast cancer nationwide, it is common for ob-gyn practitioners to encounter patients who have a family history of breast cancer or who have been diagnosed with breast cancer themselves. It is important to identify those who may be at increased lifetime risk of breast cancer with interventions that can facilitate early detection or decreased future risk of breast cancer.
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