Academic journal article
By Buxton, Jane A.; Bottorff, Joan L.; Balneaves, Lynda G.; Richardson, Chris; et al.
Canadian Journal of Public Health , Vol. 94, No. 6
Background: The objective was to compare women's personal estimates of their risk with objective breast cancer risk estimates and to describe the risk factors for breast cancer identified by women.
Methods: Telephone survey of a random sample of 761 rural and urban women with no history of breast cancer. Survey instrument included measures of perceptions of lifetime risk for breast cancer for themselves and for the average woman, perceptions of risk factors that influenced their risk and the average woman's risk for breast cancer. Objective estimates of breast cancer risk were calculated using the Gail et al. algorithm. Descriptive statistics and multiple linear regression were used to analyze the data.
Results: Women's estimates of their own lifetime risk for breast cancer were significantly higher than their Gail model risk estimates (mean difference=9%, p<0.001). The women's personal breast cancer risk estimates were lower than estimates of risk for a hypothetical average woman (mean diffurence=-8%, p<0.001). Fifty percent of the sample reported a perceived risk estimate at least 15% above their Gail risk estimate. The risk factors for breast cancer most frequently identified included family history, nutrition/diet, smoking, lifestyle, environment, stress and age. Although the risk factors used to calculate the Gail model risk estimates were reported by some study participants, these women consistently identified only family history as their personal risk factor.
Conclusion: Women have difficulty accurately estimating their breast cancer risk and identifying known risk factors for breast cancer. Individual risk information may be more useful in enhancing accurate risk perceptions than the "1 in 9" message.
Health care professionals are increasingly involved in providing information and advice to women who are concerned about their risk for breast cancer. Counselling about breast cancer risk, however, may be complicated by difficulties in understanding risk estimates, probabilities, and the relative importance of breast cancer risk factors.1-3 Despite widespread availability of risk information, many women hold inaccurate perceptions of their own risk and the population risk for breast cancer.2,1-7 Misperceptions have been linked to innumeracy,8,9 limited knowledge about breast cancer,8,10 denial,4 perceived lack of control over the disease,11 and anxiety or excessive breast cancer worry.7
When American women's estimates of their personal breast cancer risk (subjective estimates) are compared to estimates obtained from the Gail et al. algorithm (objective estimates),12-14 the majority of women greatly overestimate their risk.6,9,15-17 Researchers in Britain4,7,18 and Australia19 have reported similar results. Confounding this overestimation is the observation that women lack knowledge of the most significant risk factors for breast cancer.2,3,20 To our knowledge, the most recent population-based study in Canada to assess women's perceptions of their risk for breast cancer was conducted in Montreal in 1995.10 In this study, the majority overestimated the average lifetime risk of breast cancer despite reporting being exposed to information about breast cancer. Most women considered themselves at average or low risk for breast cancer as compared to other women their age.
Ongoing study of risk perceptions and the risk factors women associate with breast cancer are needed to identify trends in their understanding of breast cancer risk. These results will assist health care professionals in responding more effectively to requests for information about breast cancer and in providing breast cancer risk information in ways that support the development of accurate risk perceptions. The purposes of this study were to: 1) compare women's subjective and objective breast cancer risk estimates, 2) identify demographic characteristics associated with discrepancies between objective and subjective assessments of breast cancer risk, 3) describe the risk factors for breast cancer that women identify for a hypothetical "average" woman and for themselves, and 4) describe the relationship between perceived risk and breast cancer screening practices. …