Women at High Risk for Breast Cancer May Benefit from Starting Mammography at Age 40For women with twice the average risk of developing breast cancer, the benefits and harms of beginning biennial (every-other-year) screening mammography at age 40 are similar to those for average-risk women aged 50 to 74 screened biennially, according to a new modeling study. These results, published May 1 in the Annals of Internal Medicine, may provide important information to move toward individualized, risk-based screening, the study authors wrote.
A companion paper published in the same issue of Annals identified women aged 40 to 49 with a first-degree relative with breast cancer or with extremely dense breasts (Breast Imaging Reporting and Data System category 4 breast density) as having double the average risk of breast cancer.
To determine which women younger than 50 might benefit from mammography at a level similar to those aged 50 to 74, Nicolien van Ravesteyn of Erasmus Medical Center in the Netherlands and her colleagues used four breast cancer models developed by the NCI-funded Cancer Intervention and Surveillance Modeling Network (CISNET). These models allowed the authors to estimate the benefits and harms associated with mammography screening for women in their 40s under a variety of different assumptions about a woman’s risk of developing breast cancer. The models also incorporated additional data on film and digital mammography use in community practices from the Breast Cancer Surveillance Consortium.
Among younger women, screening mammography prevents fewer deaths because their risk of breast cancer is lower to begin with, explained the authors. Thus, for most younger women, the harms of screening mammography may outweigh the benefits.
According to the models, for women with twice the average risk of developing breast cancer, “the balance of benefits and harms…of starting biennial screening at age 40 years approximates that of biennial screening for average-risk women starting at age 50 years,” wrote the authors. In the models, annual screening added little benefit, and the risk of false-positive results was higher with digital mammography than with film mammography.
“Decisions related to screening women in their 40s on a personal or public policy level are complex, and these results add to the body of knowledge available to inform these decisions,” said Dr. Kathy Cronin of NCI’s Surveillance Research Program and scientific coordinator of the CISNET breast cancer group. “The results do not directly answer the question of which women should be screened in their 40s, but rather highlight the importance of including individual risk in the discussion between women and their physicians.”