Women’s awareness and perceived importance of the harms and benefits of mammography screening : Results from a 2016 national survey

There is growing scientific consensus that mammography has a modest impact on averting deaths from breast cancer, while exposing women to a number of harms. Yet it is not well known how women in the general US public perceive the benefits and harms of mammography screening. Previous research has been published on public enthusiasm for screening and underestimates of harms, but these findings may be outdated. In this study, we present 2016 data on women’s awareness and perceptions of the benefits and harms of mammography, drawn from a larger survey of US adults on exposure to cancer-related information in the media.

Methods : Study participants were recruited by GfK, a survey research firm that maintains a probability-based panel of approximately 55 000 adults. GfK recruits panel participants through address-based probability sampling and provides small financial incentives to panel members for completing surveys. Among eligible panelists randomly selected to participate, 1519 (51%) completed the online survey between May 24 and June 6, 2016. Data reported herein are restricted to US women aged 40 to 59 years (n = 407) who received a stand-alone module about (1) awareness of the benefits/harms of mammograms, and (2) evaluations of the importance of these benefits/harms (Table 1 and Table 2). Both the question blocks, and the items within these blocks, were randomized. Prior to these items, respondents answered questions about their general and mammogram-related news and health media consumption. They also answered 2 items (“have you ever had a mammogram” and “when did you have your most recent mammogram to check for breast cancer”), which we used to construct 3 categories of mammogram history: (1) never had a mammogram, (2) had over a year ago, and (3) had less than a year ago. We tested for differences in importance evaluations by mammogram history using ordered logit regression. Analyses applied the GfK survey weights to adjust for nonresponse bias and panel nonresponse to produce nationally-representative estimates. The study was determined to be exempt from review by the University of Minnesota institutional review board.

Results : Fifty-eight (14.2%) participants reported never having a mammogram, 197 (56.4%) reported having a mammogram within the past year, and 103 (29.4%) reported having a mammogram less recently. Nearly all respondents (366, >90% for each) were aware of 4 statements describing mammography benefits (Table 1). When asked to rate their importance, most (223 [54.8]) concluded that each benefit was “very important.” Respondents’ awareness of harms, however, was much more variable (Table 2). Although only 108 (26.5%) reported prior awareness of overdiagnosis and 161 (39.7%) of overtreatment, 305 (74.9%) were aware of false-positive results and the potential of psychological distress. In contrast to their evaluations of benefits, fewer women rated harms as very important, ranging from 61 (15.1%) (health care system costs) to 117 (28.7%) (overtreatment). There were no statistically significant differences in awareness or ratings of importance by age group (40-49 years vs 50-59 years). Women who reported having a mammogram within the past year were significantly more likely to rate all 4 benefits as very important, compared with those who who never had a mammogram (62.4%-74.9% vs 44.9%-58.0%; differences significant at P<.05). Women who reported having a mammogram within the past year were significantly less likely to rate health care system costs and radiation harms as very important compared with those who never had a mammogram (11.5% and 15.1% vs 22.9% and 25.7%; differences significant at P<.05).

Discussion : Women are more aware of the benefits of mammography screening than the harms, and women who have recently undergone mammography are more likely to judge these benefits as important. This may be owing to a lack of balanced information from physicians,5 public health officials, news media, and disease advocacy groups that have long emphasized screening’s benefits. Our findings suggest that there are opportunities for targeted education and communication at both the general public and individual levels, with a focus on educating women on the harms of screening, which they are much more likely to experience than benefits. However, the fact that women are predisposed to consider benefits as more important than harms poses a challenge to informed decision making about screening, suggesting the need for new paradigms in communicating the cumulative risks of the benefits and harms.

JAMA Internal Medicine , article en libre accès, 2016

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