A mammography screening decision aid with information about the benefits and harms of screening increased the percentage of average-risk women in their 40s who wanted to delay mammography, according to a national online survey.

Before viewing the decision aid, 27% of women ages 39 to 49 preferred to delay screening. The decision aid raised that percentage to 38.5%, reported Laura Scherer, PhD, of the University of Colorado in Aurora, and colleagues.

The survey also showed a narrower majority of women preferred to undergo mammography at their current age after viewing the decision aid (57.2% vs 67.6% beforehand) and more preferred to wait until age 50 (18% vs 8.5%).

As to what information shifted their view, 37.4% of women surveyed said they found the information about overdiagnosis in the decision aid “surprising,” and 28.1% said it differed from what their doctor had told them, Scherer and colleagues reported in the Annals of Internal Medicine.

While the U.S. Preventive Services Task Force (USPSTF) recommends biennial screening starting at age 40 years — compared with a previous recommendation that screening begin at 50 — it “endorses informed choice and shared decision making at all levels of its recommendations,” Scherer’s group wrote.

However, “a lack of language promoting informed choice in the guideline itself may create confusion among clinicians about whether they should discuss both screening benefits and harms with patients or instead provide only information that maximizes screening uptake,” they added.

How information is presented makes a difference, observed Victoria Mintsopoulos, MD, MSc, and Michelle Nadler, MD, both of the University of Toronto, in an editorial accompanying the study.

For example, the decision aid in the study presented overdiagnosis risk as a percentage of all screening-detected cancers (12-22%), which may be perceived as more risky than when presented as an absolute number (1-3 cases per 1,000 persons screened), they pointed out.

Presenting all benefits and harms in absolute numbers with a common denominator may be the most transparent for women to make an informed decision, the editorialists suggested.

Considering the benefits and harms of breast cancer screening are closely balanced, Mintsopoulos and Nadler suggested research should focus on determining the best method of providing shared decision making or using decision aids, “ensuring that all women who are eligible for [breast cancer] screening have access to providers who can engage with them using these tools, and ensuring that those who want screening (after informed consent) have access to it.”

The study surveyed 495 women ages 39 to 49 years without a history of breast cancer or a known BRCA1/2 gene mutation to assess screening preferences before and after receipt of the decision aid.

Participants were recruited for the survey using the Ipsos KnowledgePanel, which uses address-based sampling to maintain a diverse national panel of participants and provide a statistically valid representation of the U.S. population.

This study used a pre-post design in which all participants received the decision aid presenting information on screening recommendations from the USPSTF and American Cancer Society as of 2022, screening benefits, false-positive screening results, overdiagnosis, a personal risk estimate, and decision-making vignettes.

After seeing the decision aid, the proportion of women never wanting mammography didn’t increase (5.4% before vs 4.3% after). And notably, those with higher breast cancer risk preferred earlier screening.

Scherer and colleagues reported that commonly stated reasons for preference to delay screening included a lack of family history, low cancer risk, as well as concerns about screening harms.

“These data suggest that many people who want to delay screening are considering the evidence and deciding that, for them, the harms outweigh the benefits at their current age,” they wrote.