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Many women don’t believe their breast cancer risk numbers

A study’s author says women’s skepticism about risks leads some to put off preventive medicine, while others may undergo unnecessary treatments.

By — Posted Sept. 2, 2013

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Telling patients how likely they are to develop breast cancer within the next five years might not be enough to ensure that women make informed decisions related to that risk, a recent study said.

Nineteen percent of women who completed a breast cancer risk assessment survey didn’t believe their calculated five-year risk. They also did not believe estimates on how much their cancer risk would be reduced by taking the chemoprevention drugs tamoxifen or raloxifene, according to the study in the August issue of Patient Education and Counseling.

“If people don’t believe their risk numbers, it does not allow them to make informed medical decisions,” said senior study author Angela Fagerlin, PhD, an associate professor of medicine at the University of Michigan Medical School. “Women who believe their risk is not high might skip chemoprevention strategies that could significantly reduce their risk. And women who think their risk should be higher could potentially undergo treatments that might not be medically appropriate.”

To help alleviate that problem, physicians should take a few extra minutes to explain to patients what factors were used to estimate their likelihood of developing cancer and why other information wasn’t included in the assessment, said Laura D. Scherer, PhD, first study author.

Patients “might need more guidance than throwing a number out there and saying, ‘It’s personalized,’ ” said Scherer, an assistant professor of psychology at the University of Missouri.

Breast cancer is the second-leading cause of cancer death in women, exceeded only by lung cancer, according to the American Cancer Society. An estimated 232,340 new cases of invasive breast cancer are expected to be diagnosed in women in 2013, and about 39,620 women will die of the disease, the society said.

Explaining risks and benefits

Researchers examined data on 690 women ages 46-74 who lived in Detroit or Seattle and had an average or above average risk of developing breast cancer. Patients’ cancer risks were estimated using the Breast Cancer Risk Assessment Tool, a seven-question survey that was completed online.

The tool calculated women’s absolute risk of developing breast cancer within five years using several factors. Those factors include the patient’s age, ethnicity, personal history of breast cancer, age at first menses and number of first-degree relatives with the disease. First-degree relatives were defined as aunts, daughters, mothers and sisters.

When the survey was completed, patients received an online decision aid about breast cancer and chemoprevention. The aid provided each woman with tailored estimates of her absolute five-year risk of breast cancer, as well as information on how much that risk would be reduced by choosing to take tamoxifen or raloxifene.

Decision aids for half of the study participants detailed the factors that were used to calculate their tailored risk number. The other women simply were informed that their risk calculation was based on “women like you.”

After receiving the decision aid, participants were asked to recall their two breast cancer risk estimates. If they answered incorrectly, they were asked whether it was because they forgot, made a rounding error or disagreed with the number.

The most common reason for misreporting both numbers was disagreement with the estimates. Of those women, 37% didn’t think the estimates adequately accounted for their family history, and 25% said the risk seemed too high or too low. Other reasons for not believing risk figures were lifestyle and health habits (21%) and personal medical history (15%).

Fifteen percent of women said they misreported both estimates because they forgot the number, and 14% said they experienced a rounding error.

The study findings highlight the challenges doctors face in trying to educate patients on the risks and benefits of disease prevention, including mammograms and other efforts, in a limited amount of time, said Chicago family physician Ravi Grivois-Shah, MD, MPH.

“We’re getting inundated by recommendations that are very unclear,” he said. “I don’t use risk numbers with my patients [because they’re confusing] and they mean nothing to me as a provider. High or low risk” is how he explains it.

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External links

“Belief in Numbers: When and Why Women Disbelieve Tailored Breast Cancer Risk Statistics,” Patient Education and Counseling, August (link)

Breast cancer information, American Cancer Society (link)

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