From the Guidelines
Having heterogeneously dense breasts (HDB) increases the risk of developing breast cancer by a factor of 1.2 compared to average breast density, and dense breast tissue can make it more difficult for radiologists to detect small cancers on mammography. According to the most recent study 1, dense breast tissue is an independent risk factor for developing breast cancer, and the relative risks for developing breast cancer are 1.2 for heterogeneously dense and 2.1 for extremely dense breasts.
Key Considerations
- Heterogeneously dense breast tissue is a common finding, occurring in approximately 40% of women.
- Dense breast tissue decreases the sensitivity of mammography 1 and is associated with a slightly increased risk of developing breast cancer.
- Digital Breast Tomosynthesis (DBT) screening is recommended as it increases cancer detection rate (CDR) and decreases recall rate compared to digital mammography alone 1.
- The American College of Radiology (ACR) recommends annual screening mammography beginning at 40 years of age for women at intermediate risk 1.
- Women with heterogeneously dense breasts should continue with recommended mammograms according to their age and risk factors, and consider discussing supplemental screening options with their healthcare provider, such as breast ultrasound or MRI, especially if they have other risk factors for breast cancer.
Lifestyle Factors
- Maintaining a healthy weight, limiting alcohol consumption, and regular exercise may help reduce breast cancer risk regardless of breast density.
- The density of the breasts may change over time, particularly with age, weight changes, or hormonal fluctuations.
Screening Recommendations
- The ACR recommends screening DBT in average-risk women each year beginning at 40 years of age 1.
- Women should continue screening mammography as long as they remain in overall good health and are willing to undergo the examination and subsequent testing or biopsy, if an abnormality is identified 1.
From the Research
Implications of Heterogeneously Dense Breasts (HDB)
The implications of having heterogeneously dense breasts (HDB) are significant, particularly in terms of breast cancer risk and detection. Women with HDB have a higher risk of breast cancer and lower mammographic tumor detectability compared to those with less dense breasts 2, 3.
Breast Cancer Detection and Screening
Studies have shown that supplemental magnetic resonance imaging (MRI) screening can improve early detection and reduce interval breast cancers in women with extremely dense breast tissue 2, 3. The use of MRI screening in women with extremely dense breast tissue and normal results on mammography resulted in the diagnosis of significantly fewer interval cancers than mammography alone during a 2-year screening period 2.
Comparison of Screening Modalities
A systematic review and meta-analysis compared the clinical outcomes of different supplemental screening modalities in women with dense breasts and negative mammography, including digital breast tomosynthesis, handheld US, automated breast US, and MRI 4. The results showed that MRI was superior to other supplemental modalities in terms of incremental cancer detection rate (CDR) and invasive CDR.
Non-Contrast MRI for Breast Screening
A preliminary study explored the use of non-contrast MRI for breast screening in women with dense breasts, using combined diffusion-weighted imaging and turbo inversion recovery magnitude MRI (DWI + TIRM) 5. The results showed that DWI + TIRM had higher accuracy and sensitivity for breast cancer detection than mammography, and was comparable to clinical MRI.
Key Findings
- Women with HDB have a higher risk of breast cancer and lower mammographic tumor detectability 2, 3
- Supplemental MRI screening can improve early detection and reduce interval breast cancers in women with extremely dense breast tissue 2, 3
- MRI is superior to other supplemental modalities in terms of incremental CDR and invasive CDR 4
- Non-contrast MRI using DWI + TIRM may be a safe and effective alternative for screening women with dense breasts 5
- Primary care providers can discuss breast density and recommend supplemental breast cancer screening using the density of the previous mammography, reducing the need for multiple appointments and patient anxiety 6
Screening Recommendations
- Women with HDB should discuss their breast density and screening options with their primary care provider 6
- Supplemental MRI screening may be recommended for women with extremely dense breast tissue and normal results on mammography 2, 3
- Non-contrast MRI using DWI + TIRM may be considered as an alternative screening modality for women with dense breasts 5