If a woman is a breast cancer survivor and has dense breasts, is mammography adequate screening?

Because many studies have shown improved detection of early, node-negative cancers with MRI even after normal mammography and ultrasound, the ACR now recommends [1] annual MRI in addition to mammography (either 2D or 3D) for the following women (provided the patient has not had bilateral mastectomy):

• All women with a personal history of breast cancer and dense breasts.
• Women with any breast density diagnosed with breast cancer by age 50.

One study from UC San Francisco [2] found that screening mammography every 6 months instead of every year improved early detection, but this is not routinely recommended. Tomosynthesis, or 3D mammography, improves cancer detection in most women (by 1-2 per 1000 screening examinations) compared to standard 2D mammography. In women with extremely dense breasts, however, tomosynthesis remains limited as cancers that lack calcifications can remain masked by overlying tissue. For women with dense breasts and prior breast cancer, screening ultrasound can be added to annual mammography, though the added cancer detection (at 2-4 per 1000 examinations) is less than that achieved with MRI (at 7-20 per 1000 examinations). Indeed, MRI is more effective at depicting early cancer in women of any breast density, even after a normal mammogram.

If MRI is performed, screening ultrasound is of no benefit. Women with a personal history of breast cancer and dense breasts who are unable to tolerate MRI may consider screening ultrasound in addition to mammography.