Abstract
This survey study examines how women in the general US population perceive the benefits and harms of mammography screening.
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research has been published on public enthusiasm for screening and underestimates of harms, but these findings may be outdated.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.
Table 1. Awareness and Perceived Importance of Mammogram Benefits, Nationally Representative Sample of 407 Women Ages 40 to 59 Years.
| Benefits | Frequency, % (95% CI) | |||
|---|---|---|---|---|
| Awarenessa | Importanceb | |||
| I Have Heard of This Before | Not At All | Slightly Important or Important | Very Important | |
| Mammograms can save lives. | 97.1 (94.8-98.4) | 1.9 (0.9-3.8) | 31.2 (26.7-36.1) | 66.9 (61.9-71.6) |
| Mammograms can lead to earlier treatment of breast cancer. | 96.2 (93.6-97.8) | 2.1 (1.1-4.0) | 31.3 (27.0-35.9) | 66.6 (61.7-71.2) |
| Mammograms can provide peace of mind by finding that you do not have breast cancer. | 92.2 (89.3-94.3) | 3.2 (1.8-5.7) | 40.3 (35.1-45.7) | 56.5 (51.1-61.7) |
| Mammograms can find cancer early, sometimes before cancer symptoms begin. | 91.2 (88.0-93.6) | 2.3 (1.2-4.0) | 31.9 (27.3-36.8) | 65.9 (60.9-70.5) |
For each benefit, respondents indicated “I have heard of this before” or “this is new information to me today.”
Respondents were asked “If you were to consider getting a mammogram in the future, how important would the following potential benefits of mammograms be to you personally?” Responses were measured on a 5-category Likert scale ranging from “not important” to “very important”; middle categories (“slightly important,” “moderately important,” and “important”) are collapsed.
Table 2. Awareness and Perceived Importance of Mammogram Harms, Nationally Representative Sample of 407 Women Ages 40 to 59 Years.
| Harms | Frequency, % (95% CI) | |||
|---|---|---|---|---|
| Awarenessa | Importanceb | |||
| I Have Heard of This Before | Not at All | Slightly Important or Important | Very Important | |
| Women who receive positive mammogram results, even if eventually it turns out they do not have cancer, may feel anxious and stressed. | 77.6 (73.2-81.3) | 14.2 (10.8-18.3) | 62.4 (56.9-67.6) | 23.5 (19.2-28.3) |
| Mammograms can find something that looks like cancer but eventually turns out not to be cancer. This is called a “false-positive” or “false alarm.” | 75.4 (70.7-79.5) | 11.8 (8.7-15.9) | 64.8 (59.1-70.1) | 23.4 (18.7-28.8) |
| Mammograms, like all x-rays, expose women to very small doses of radiation, which could increase risk for cancer. | 67.4 (62.5-71.9) | 13.2 (10.2-17.1) | 67.1 (62.3-71.7) | 19.6 (16.0-23.8) |
| Mammograms can lead to increased costs to women because of follow-up tests and procedures. | 50.1 (44.0-56.2) | 19.8 (16.0-24.3) | 61.5 (55.7-66.9) | 18.8 (14.7-23.7) |
| Mammograms can lead to increased costs to the health care system because of follow-up tests and procedures. | 42.7 (36.8-48.8) | 23.0 (18.9-27.7) | 61.9 (56.8-66.7) | 15.1 (11.5-19.6) |
| Some breast cancers found by mammograms are treated with potentially-risky surgeries or medications that would not have needed such treatment after all. | 39.7 (34.8-44.8) | 9.0 (5.9-13.5) | 62.3 (57.0-67.3) | 28.7 (24.3-33.5) |
| Some breast cancers that are found by mammograms are so slow-growing that they would not have caused any health problems for women in their lifetime. | 26.5 (21.7-31.8) | 13.4 (9.8-18.1) | 65.1 (58.7-70.9) | 21.5 (16.2-28.0) |
For each harm, respondents indicated “I have heard of this before” or “this is new information to me today.”
Respondents were asked “If you were to consider getting a mammogram in the future, how important would the following potential harms of mammograms be to you personally?” Responses were measured on a 5-category Likert scale ranging from “not important” to “very important”; middle categories (“slightly important,” “moderately important,” and “important”) are collapsed.
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, 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.
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