High-risk screening
Unlike in screening average-risk patients, there is less disagreement about screening in high-risk groups. TABLE 7 outlines the various categories and recommended strategies that qualify for screening at younger ages or more intensive screening. Adding breast MRI to SM in high-risk individuals results in both higher cancer detection rates and less interval breast cancers (cancers diagnosed between screening rounds) diagnosed compared with SM alone.19,20 Interval breast cancer tends to be more aggressive and is used as a surrogate marker for more recognized factors, such as breast cancer mortality. In addition to less interval breast cancers, high-risk patients are more likely to be diagnosed with node-negative disease if screening breast MRI is added to SM.
Long-term mortality benefit studies using MRI have not been conducted due to the prolonged follow-up times needed. Expense, lower specificity compared with mammography (that is, more false-positive results), and need for the use of gadolinium limit more widespread use of breast MRI screening in average-risk persons.
Screening in patients with dense breasts
Half of patients undergoing SM in the United States have dense breasts (heterogeneously dense breasts, 40%; extremely dense breasts, 10%). Importantly, increasing breast density is associated with a lower cancer detection rate with SM and is an independent risk factor for developing breast cancer. While most states already require patients to be notified if they have dense breasts identified on SM, the US Food and Drug Administration will soon make breast density patient notification a national standard (see: https://delauro.house.gov/media-center/press-releases/delauro-secures-timeline-fda-rollout-breast-density-notification-rule).
Most of the risk assessment tools listed in TABLE 3 incorporate breast density into their calculation of breast cancer risk. If that calculation places a patient into one of the highest-risk groups (based on additional factors like strong family history of breast cancer, reproductive risk factors, BRCA carriage, and so on), more intensive surveillance should be recommended (TABLE 7).7 However, once these risk calculations are done, most persons with dense breasts will remain in an average-risk category.
Because of the frequency and risks associated with dense breasts, different and alternative strategies have been recommended for screening persons who are at average risk with dense breasts. Supplemental screening with MRI, ultrasonography, contrast-enhanced mammography, and molecular breast imaging are all being considered but have not been studied sufficiently to demonstrate mortality benefit or cost-effectiveness.
Of all the supplemental modalities used to screen patients with dense breasts, MRI has been the best studied. A large RCT in the Netherlands evaluated supplemental MRI screening in persons with extremely dense breasts after a negative mammogram.21 Compared with no supplemental screening, the MRI group had 17 additional cancers detected per 1,000 screened and a 50% reduction in interval breast cancers; in addition, MRI was associated with a positive predictive value of 26% for biopsies. At present, high cost and limited access to standard breast MRI has not allowed its routine use for persons with dense breasts in the United States, but this may change with more experience and more widespread introduction and experience with abbreviated (or rapid) breast MRI in the future (TABLE 8).
Equitable screening
Black persons who are diagnosed with breast cancer have a 40% higher risk of dying than White patients due to multiple factors, including systemic racial factors (implicit and unconscious bias), reduced access to care, and a lower likelihood of receiving standard of care once diagnosed.22-24 In addition, Black patients have twice the likelihood of being diagnosed with triple-negative breast cancers, a biologically more aggressive tumor.22-24 Among Black, Asian, and Hispanic persons diagnosed with breast cancer, one-third are diagnosed younger than age 50, which is higher than for non-Hispanic White persons. Prior to the age of 50, Black, Asian, and Hispanic patients also have a 72% more likelihood of being diagnosed with invasive breast cancer, have a 58% greater risk of advanced-stage disease, and have a 127% higher risk of dying from breast cancer compared with White patients.25,26 Based on all of these factors, delaying SM until age 50 may adversely affect the Black, Asian, and Hispanic populations.
Persons in the LGBTQ+ community do not present for SM as frequently as the general population, often because they feel threatened or unwelcome.27 Clinicians and breast imaging units should review their inclusivity policies and training to provide a welcoming and respectful environment to all persons in an effort to reduce these barriers. While data are limited and largely depend on expert opinion, current recommendations for screening in the transgender patient depend on sex assigned at birth, the type and duration of hormone use, and surgical history. In patients assigned female sex at birth, average-risk and high-risk screening recommendations are similar to those for the general population unless bilateral mastectomy has been performed.28 In transfeminine patients who have used hormones for longer than 5 years, some groups recommend annual screening starting at age 40, although well-designed studies are lacking.29
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