When asked to estimate the lifetime risk of breast cancer, 89 percent of women overestimated their risk, with an average estimate of 46 percent - more than three times the actual risk of 13 percent, according to a study by University of Michigan Health System researchers.
"Breast cancer is so commonly in the news, and most of us can think of friends or relatives who have been diagnosed with it. That leads us to overestimate how common it really is. We forget that we know a lot of people with breast cancer because we know a lot of people," says senior study author Peter Ubel, M.D., professor of internal medicine at the U-M Medical School and director of the Center for Behavioral and Decision Sciences in Medicine.
Results of the study appear in the June issue of the journal Patient Education and Counseling.
In the study, researchers surveyed 356 women. Half the women were asked to estimate the average woman's lifetime risk of developing breast cancer, and half were not asked for an estimate. Both groups then received information on breast cancer risk.
The group that did not estimate risk beforehand was asked whether the 13 percent risk was higher or lower than they had expected. Only 37 percent said the actual risk was lower than they had expected - compared to 89 percent of women in the other group who initially thought the risk was much higher.
The researchers then asked women from both groups how anxious or relieved the information made them and whether they thought a 13 percent risk was high or low.
The women who did not give an estimate first were more likely to feel anxious about the breast cancer risk information, 25 percent vs. 12 percent of women who gave an estimate first. At the same time, twice as many women who gave an estimate beforehand said they were relieved by the actual risk, 40 percent vs. 19 percent.
"After estimating that 46 percent of women will be diagnosed with breast cancer, when they find out it's actually 13 percent, that seems relatively low and women feel a sense of relief," says lead study author Angela Fagerlin, Ph.D., research investigator in internal medicine at the U-M Medical School and with the VA Ann Arbor Healthcare System.
The researchers suggest doctors can use these findings to help patients who seem particularly concerned about their risk of breast cancer.
"Doctors need to be in touch with their patients' needs. If a woman is unduly anxious about her risk of breast cancer, and that anxiety is ruining her life, it might help to ask her what she thinks her chance of breast cancer really is. She is likely to overestimate that risk, and now the doctor will have a chance to tell her the true risk and, potentially, put her mind at ease," says Ubel, a staff physician at the VA Ann Arbor Healthcare System.
At the same time, the researchers stress, overestimating the risk does not diminish the importance of prevention strategies, such as yearly mammograms and monthly breast self exams.
In addition to Fagerlin and Ubel, Brian Zikmund-Fisher, a research investigator in the U-M Department of Internal Medicine, was a study author. Funding for the study was from the National Institutes of Health, the Department of Veterans Affairs and a Presidential Early Career Award for Scientists and Engineers.
For more information on breast cancer, visit www.cancer.med.umich.edu/learn/breastinfo.htm or call the Cancer AnswerLine at 800-865-1125.
Reference: Patient Education and Counseling, Vol. 57, issue 3, pp. 294-299