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

Often not. Across all breast densities, compared to women without a history of breast cancer, mammography is less sensitive and interval cancer rates are higher in women who have had breast cancer [1]. Women diagnosed before the age of 50 or with dense breasts are especially likely to have subsequent breast cancer missed by screening mammography [2]. In these high-risk women, early detection of second breast cancers has been shown to improve survival [3], so there are guidelines recommending additional screening beyond mammography.

Tomosynthesis, or 3D mammography, improves cancer detection in most women (by 1-2 per 1000 screening examinations) compared to standard 2D mammography. In all women with dense breasts, however, tomosynthesis remains limited, as cancers that lack calcifications can be masked by overlying tissue. For women with dense breasts and prior breast cancer, the American College of Radiology now recommends [4] annual MRI in addition to either 2D or 3D mammography 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.

Women with a personal history of breast cancer diagnosed after age 50 even with breasts that are not dense should strongly consider supplemental screening with MRI, especially if other risk factors are present.

If breast MRI is not possible, contrast-enhanced mammography (CEM) or molecular breast imaging (MBI) are other options. Ultrasound can be considered if these options are not possible.

What are the data?

Several supplemental screening methods improve detection of early, node-negative invasive breast cancers in women with a history of breast cancer. MRI will show the most cancers, even after combined mammography (and several studies also used ultrasound), at an average of 15 per 1000 examinations [5-11]. If MRI is not possible, contrast-enhanced mammography may be considered, which improves cancer detection in women who have undergone breast conservation over digital mammography (15 vs. 6 per 1000 examinations, respectively) [12]. If these options are not possible or not available, 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 or CEM. Ultrasound is not indicated for screening women who have had screening MRI [13].