In addition, a new study finds that most women who wanted to delay their mammograms were at low risk of breast cancer.
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Around 20 percent of women in their 40s would delay their breast cancer screenings until around age 50 if given an informed choice, according to survey findings published Monday in the Annals of Internal Medicine.
The study found that women who chose to delay their mammograms, an imaging method for early detection of breast cancer, were usually at low risk of breast cancer and were concerned about harms caused by overdiagnosis.
“Commonly stated reasons for delaying screening included lack of family history, low cancer risk, and concern about screening harms,” the study authors, most of whom were researchers from the University of Colorado, wrote in the paper.
“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.
Informed Consent Changes Screening Decisions
The survey evaluated nearly 500 women aged 39 to 49. Women were given a decision aid to help them decide whether to participate in breast cancer screening. Two-thirds of the women had already had a prior mammography.
The decision aid disclosed the possible harms of overdiagnosis. For example, it noted that out of 1,000 women screened between 40 and 49, 239 experienced a false positive result, and 220 women aged 50 to 59 experienced one.
The aid also reported that starting screening at age 40 would save one additional life out of 1,000 people screened. However, it did not communicate other benefits of early detection, such as the potential for less intensive treatment if cancer were detected.
Survey participants were also given a personal breast cancer risk score based on the National Cancer Institute’s personal risk calculator.
Most women surveyed (57.2 percent) preferred to have a mammography even after being informed of its benefits and potential harms.
Before reading the decision aid, 8 percent said they wished to delay a mammogram. After reading it, 18 percent said they would delay getting mammograms until they turned 50.
Most women who chose to delay it were those deemed to have a lower breast cancer risk, while those with a high risk of breast cancer did not want to delay screening.
However, the authors did not see an increase in the number of women who reported never wanting to undergo a mammogram after reading the decision aid.
Surprised by Overdiagnosis Data
Although mammography may save lives, it also comes with certain risks, including false positives, unnecessary biopsies, and overdiagnosis.
False positives are pretty common. One study showed that one in 10 women getting screened for breast cancer for the first time will receive a false positive.
In the United States, the likelihood that a woman who tests positive for breast cancer actually has it is roughly 7 percent, according to a study by the National Cancer Institute. However, other research states that this percentage could vary from as low as 4 percent to as high as about 50 percent.
The survey results showed that women were surprised by the statistics on overdiagnosis, with around 37 percent expressing this.
Nearly the same percentage of women also reported that the data presented on overdiagnosis were “very different” from what they believed before.
From 2009 until the study was conducted in 2022, the U.S. Preventive Services Task Force (USPSTF) advised that screening should be an individual’s decision for those aged 40 to 49. However, in April 2024, the USPSTF changed the guideline, recommending biennial breast cancer screenings for all women starting at age 40.