Screening modalities
Digital 3-D mammography, or digital breast tomosynthesis (DBT), is widely considered to be a more sensitive screening tool than conventional digital mammography alone. The NCCN recommends DBT for women with an average risk of developing breast cancer starting at age 40,4,5 and the USPSTF, while offering no recommendation on DBT as a primary screening method (“insufficient evidence”), says that DBT appears to increase cancer detection rates.2 So, I do routinely recommend it.
DBT may be especially beneficial for women with dense breast tissue (determined mammographically), who are most often premenopausal women – particularly non-Hispanic White women. Dense breast tissue itself can contribute to an increased risk of breast cancer – an approximately 20% higher relative risk in an average-risk woman with heterogeneously dense breast tissue, and an approximately 100% higher relative risk in a woman with extremely dense breasts6 – but unfortunately it affects the sensitivity and specificity of screening mammography.
I do not recommend routine supplemental screening with other methods (breast ultrasonography or MRI) for women at average risk of breast cancer who have dense breasts. MRI with gadolinium contrast is recommended as an adjunct to mammography for women who have a lifetime risk of developing breast cancer of more than 20%-25% (e.g., women with known BRCA1/2 mutations or radiation to breast tissue), and can be done annually at the same time as the screening mammogram is done. Some clinicians and patients prefer to alternate these two tests – one every 6 months.
Screening breast MRI is more sensitive but less specific than mammography; combining the two screening modalities leads to overall increased sensitivity and specificity in high-risk populations.
Risk assessment
Identifying higher-risk women who need to be sent to a genetic counselor is critically important. The USPSTF recommends that women who have family members with breast, ovarian, tubal or peritoneal cancer, or who have an ancestry associated with BRCA1/2 gene mutations, be assessed with a brief familial risk assessment tool such as the Pedigree Assessment Tool. This and other validated tools have been evaluated by the USPSTF and can be used to guide referrals to genetic counseling for more definitive risk assessment.7
These tools are different from general breast cancer risk assessment models, such as the NCI’s Breast Cancer Risk Assessment Tool,8 which are designed to calculate the 5-year and lifetime risk of developing invasive breast cancer for an average-risk woman but not to identify BRCA-related cancer risk. (The NCI’s tool is based on the Gail model, which has been widely used over the years.)
The general risk assessment models use a women’s personal medical and reproductive history as well as the history of breast cancer among her first-degree relatives to estimate her risk.
Dr. Tkaczuk reported that she has no disclosures.
References
1. “Cancer Stat Facts: Female Breast Cancer.” Surveillance, Epidemiology, and End Results Program. National Cancer Institute.
2. Siu AL et al. Ann Intern Med. 2016 Feb 16. doi: 10.7326/M15-2886.
3. Independent UK Panel on Breast Cancer Screening. Lancet. 2012 Nov 17;380(9855):1778-86.
4. NCCN guidelines for Detection, Prevention, & Risk Reduction: Breast Cancer Screening and Diagnosis. National Comprehensive Cancer Network.
5. NCCN guidelines for Detection, Prevention, & Risk Reduction: Breast Cancer Risk Reduction. National Comprehensive Cancer Network.
6. Ziv E et al. Cancer Epidemiol Biomarkers Prev. 2004;13(12):2090-5.
7. USPSTF. JAMA. 2019;322(7):652-65.
8. The Breast Cancer Risk Assessment Tool. National Cancer Institute.