The draft recommends, at a “B” level, screening mammography for women ages 40 to 74 every two years. It also says evidence is insufficient to recommend screening mammography in women 75 and older, or to recommend supplemental screening for breast cancer with ultrasonography or MRI in women who have dense breast tissue but an otherwise negative screening mammogram.
The recommendations would apply to cisgender women and all other people assigned female at birth age 40 or older who are at average risk of breast cancer. They would apply to people with a family history of breast cancer and to those who have other risk factors such as having dense breasts, but not to people with a genetic marker or syndrome associated with an increased risk of breast cancer; a history of high-dose radiation therapy to the chest at a young age; or previous breast cancer or a high-risk breast lesion on previous biopsies.
It should be emphasized that this is a draft and is subject to additional review. The task force will consider all comments before issuing a final recommendation statement.
The draft differs slightly from the recommendations of other organizations, including the American Cancer Society and the American College of Obstetricians and Gynecologists.
Breast cancer is the second most common type of cancer and the second-leading cause of cancer death among women in the United States. The CDC estimates that more than 264,000 new breast cancers were reported in women, and more than 42,000 women died from breast cancer in the U.S. in 2019.
The draft recommendation, if finalized in its current form, would significantly expand the population for whom breast cancer screening is recommended. The task force previously recommended screening mammography for women ages 50 to 74 every two years while individualizing the decision to undergo screening in women younger than 50, based on factors such as personal preference and concerns about the benefits and harms of screening. As a result, the USPSTF estimates that 19% more lives could be saved by starting screening for breast cancer in all women beginning at age 40.
To update the previous recommendation, the USPSTF commissioned a systematic evidence review on the benefits and harms of various mammography-based breast cancer screening strategies by age, taking into account factors such as when to start and stop screening, screening interval, the modality used, the use of supplemental imaging and personalization of screening. The task force also commissioned collaborative modeling studies from the Cancer Intervention and Surveillance Modeling Network to updatea information on the benefits and harms of breast cancer screening strategies.
Although the evidence review identified no new studies on the benefits and harms of lowering the age of initiation for screening mammography from age 50 to 40, the task force relied on two other sources that led to the conclusion to recommend screening beginning at age 40.
The first source was population-based data from the National Cancer Institute’s Surveillance Epidemiology and End Results program, which found that the invasive breast cancer incidence rate in women ages 40 to 49 has increased an average of 2% annually between 2015 and 2019, a higher rate than in previous years.
The second source — the modeling analysis — concluded that screening every two years, starting at age 40 or 45, and ceasing screening at age 79 resulted in “greater incremental gains in survival and mortality reduction per mammogram” compared with most strategies that involved annual screening, a start age of 50 years and cessation at age 74.
The modeling data estimated that compared with screening every two years from ages 50 to 74, biennial screening beginning at age 40 would prevent an additional 1.3 breast cancer deaths per 1,000 women screened over a lifetime of screening for all women. For Black women specifically, the model estimated that biennial screening starting at age 40 would result in 1.8 fewer breast cancer deaths per 1,000.
Regarding the recommendations that had insufficient evidence, the task force stated that although collaborative modeling suggests a benefit to breast cancer screening in women 75 and older, no randomized clinical trials of breast cancer screening in the evidence review included women in that age range. In addition, a trial emulation found no benefit in screening women ages 75 to 84.
The task force also said that although dense breast tissue reduces the sensitivity and specificity of mammography and is associated with an increased risk of breast cancer, increased tissue density is not associated with higher breast cancer mortality among women diagnosed with breast cancer after adjusting for a number of factors.
Finally, the task force noted several potential harms of screening mammography, including false-positive results, overdiagnosis and overtreatment, and radiation exposure. The USPSTF also said the available evidence “suggests a more favorable trade-off of benefits vs. harms” with biennial vs. annual screening.
The task force noted a number of evidence gaps in its evidence review and outlined four particular areas of concern. Specifically, the task force stated that more research is needed to