When should screening mammography begin and stop?

Based on randomized trials (invitation to screening) mammography, there is at least a 15% decrease in deaths due to breast cancer in women screened in their 40s and a 22% reduction in deaths among women screened from ages 50 to 74 [1]. In observational studies of women actually having mammographic screening, reduction in deaths due to breast cancer is closer to 40% [2, 3]. Based on these results, the American College of Radiology (ACR) recommends annual screening beginning at age 40 for women at average risk for breast cancer [4]. The European Society of Breast Imaging (EUSOBI) recommends biennial screening mammography for average-risk women aged 50–69 years; extension up to 73 or 75 years biennially and from 40–45 to 49 years, annually [5]. Breast cancer incidence peaks earlier, in the 40s, for African American, Asian, and Hispanic women [6], than for Caucasian women when the peak is in the early 50s. As such, it is especially important for African American, Asian, and Hispanic women to start screening by age 40. The age to stop screening should be based on a woman’s overall health status. Women with a life expectancy less than 5-7 years are unlikely to realize a benefit from screening mammography.

Women at high risk for breast cancer, because of known or suspected disease-causing mutations in BRCA or other genes such as P53, should begin screening earlier; American Cancer Society recommendations, as well as those of the European Society of Mastology (EUSOMA), include annual MRI [7, 8]: BRCA-1 carriers should begin by age 25, and BRCA-2 carriers by age 30. Women with a history of radiation therapy to the chest (e.g., for Hodgkin’s disease) before age 30 should begin screening with mammography and MRI at age 25, or 8 years after treatment, whichever is later. Emerging evidence suggests that for BRCA-1 carriers who have annual MRI, the benefit of mammography is relatively small before age 40 [9]. Once a woman has had breast cancer, she should have at least annual mammography; if she also has dense breasts and/or was diagnosed with breast cancer by the age of 50, the ACR recommends she consider annual MRI in addition to mammography [10].

For other women with a family history of breast cancer, it is important to consider many factors, including the age at diagnosis of family members. Several risk models have been developed. While all models can over- or underestimate risk in a given individual, the Tyrer-Cuzick model is the most consistently accurate and, as of September 2017, includes breast density as a risk factor. For women estimated to have a lifetime risk of breast cancer of 20% or more, annual MRI screening has been recommended in addition to mammography [7, 10].