Does better information lead to better decisions?
by Aparna Vidyasagar
Illustration by Grace Molteni
The way medical professionals talk about mammograms is changing, so say the authors of a new research study published in The Lancet, an international medical journal. Researchers from the University of Sydney describe a shift from “uninformative and persuasive approaches” to giving “clear and balanced information” about the risks and benefits of undergoing mammograms.
The study looked at the decisions women made once they reviewed more information about mammograms, particularly about the phenomenon of “over-diagnosis.” According to a release about the study, “Over-detection and over-diagnosis refers to the diagnosis and treatment of breast cancer that would not have presented clinically during a woman’s lifetime.”
Regular mammograms have long been recommended to women older than 40 as a tool to recognize tumors, even those that can’t yet be felt as lumps. These detailed X-rays of the breast are also used to diagnose whether or not tumors are cancerous. The obvious upside of the procedure is that women with cancerous tumors can receive treatment earlier than they otherwise might. But the potential for earlier detection must be weighed against the possibility of finding false positives—that is, being diagnosed as having an abnormal mammogram when the results are actually normal— and over-diagnosis—that is, finding and unnecessarily treating a non-cancerous tumor.
According to 2013 statistics from the American Cancer Society, 67 percent of women get mammograms each year. The Lancet study states that over-diagnosis, and any treatment that follows, can affect a woman’s physical health and emotional well being. Some women who undergo radiotherapy are subject to an increased risk of heart disease or feelings of emotional distress. According to Kirsten McCaffery, a health communications specialist and one of the study’s authors, the current consensus within the medical community is that over-diagnosis occurs in around 15 percent of those screened. A review of breast cancer screening in the United Kingdom put that number as low as 11 percent and as high as 19 percent in certain instances. Yet past research has found that women in the U.K. and Australia are not well informed of the frequency and effects of over-diagnosis.
The women who participated in the study had not been screened in the past 2 years and they didn’t have a strong family history of breast cancer. They were around the age of 50, which according to the study is the age when screening is started in many countries. Participants were given one of two informational packets with slightly different content. One group (408 women) was told about the benefits of mammography and the chances of finding false positives. The second group (409 women) received identical information about mammography and the chances of finding false positives, but was also given information defining the concept of over-diagnosis and how often it occurs.
Women who received information about over-diagnosis more often made an “informed choice”. An informed choice being one where the women demonstrated adequate understanding of the material and their feelings about mammography matched their final decision whether to screen or not. Women were considered adequately informed if they understood certain certain key concepts—the benefits and harms of screening, false positives and over-diagnosis—and they had a numerical understanding of each of these issues. “They had to have some ballpark numeric understanding of the size of the problem,” said McCaffery. Some of the women demonstrated inadequate understanding after reading the materials but wanted to screen anyway
The women who received information about over-diagnosis were also more likely to choose not to undergo mammography screening. This is interesting because it suggests that if women become better informed they may also be less likely to choose screening.
This particular finding has its critics. In a recent Guardian article, Kathy Wells, Breast Cancer Network Australia’s policy manager, said she was in favor of giving women “full health information.” However, Wells felt that the benefits of screening “far outweighed” the limitations. She was concerned that doctors would not always be able to predict which cancers would become harmful.
The Lancet study is noteworthy because for the first time women’s opinions about mammography screening and intentions to screen have been measured in the form of a randomized clinical trial, generating hard numbers.
Studies with a similar focus have also been conducted in the United States. Recently, a team designed an informational packet for women over the age of 75 who had been screened before and were deciding whether to undergo routine follow-up screening. Though the group was smaller, researchers found that once the women were better informed, they more often chose not to screen.
These studies suggest that women are more inclined to avoid mammograms once they fully understand the benefits and limitations of the technology, begging the question: have women been trading the promise of good health for the opportunity to make informed decisions?
“We think it’s very clear now that the benefits versus the harms of screening are very finely balanced,” said McCaffery. “It’s a line-ball call whether it’s worth it or not. And that’s down to an individual’s values and preferences.”
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Aparna Vidyasagar is a freelance science writer who writes about life-sciences research and health. She lives in Portland, Oregon. Follow her on Twitter @aparnavid.
Grace Molteni is a Midwest born and raised designer, illustrator, and self-proclaimed bibliophile, currently calling Chicago home. For more musings, work, or just to say hey check her out on Instagram or at her personal website.
