PERCEPTIONS OF BREAST-CANCER RISK AND SCREENING EFFECTIVENESS IN WOMEN YOUNGER THAN 50 YEARS OF AGE

Background: The National Cancer Institute has recently changed its app roach and has substituted summary-of-evidence statements for specific recommendations for breast cancer screening in women 40-50 years of ag e, leaving these women with a greater share of decision-making respons ibility. To make an informed decision about breast cancer screening, w omen need accurate information about their breast cancer risk and the benefit of screening. Although it has been suggested that women younge r than 50 years of age overestimate this risk and benefit, their estim ates have not been quantified. Purpose: The purpose of this study was to determine how women 40-50 years of age perceive their risk of breas t cancer and the effectiveness of screening and how these perceptions compare with estimates derived from epidemiologic studies of breast ca ncer incidence and randomized clinical trials of screening. Methods: W e mailed a questionnaire to 200 women, identified through the computer ized medical records of Dartmouth-Hitchcock Medical Center, who were b etween 40 and 50 years of age and had no history of breast cancer. Eac h woman was asked about her risk factors for breast cancer and asked t o estimate her probabilities of developing breast cancer and dying of it within 10 years, with and without screening. The women's answers we re compared with individual probabilities derived from the Call et al, model, age-specific probabilities of developing and dying of breast c ancer in the United States, and the results of randomized clinical tri als of screening. Results: The mailed questionnaire was completed and returned by 145 (73%) of the 200 women. Respondents overestimated thei r probability of dying of breast cancer within 10 years by more than 2 0-fold (median, 22.3; interquartile range, 11.1-74.2). Assuming a 10% relative risk reduction from screening, respondents overestimated the relative risk reduction by sixfold (median, 6.0; interquartile range, 5.0-7.5) and the absolute risk reduction more than 100-fold (median, 1 27.5; interquartile range, 47.1-399.6). The median perceived estimate of absolute risk reduction was 6.0 breast cancer deaths per 100 women; the median calculated estimate was only 0.04 per 100 women. Conclusio n: These findings suggest that many women younger than 50 years of age substantially overestimate their breast cancer risk and the effective ness of screening. Implications: A balanced presentation of informatio n about breast cancer risk and screening effectiveness may improve dec ision making for women younger than 50 years of age and reduce their a nxiety about breast cancer, regardless of whether they choose to be sc reened.