Informing Women About Overdetection in Breast Cancer Screening: Two-Year Outcomes From a Randomized Trial

Abstract

Background Supporting well-informed decisions about breast cancer screening requires communicating that inconsequential disease may be detected, leading to overdiagnosis and overtreatment. Having previously shown that telling women about overdetection improved informed choice, we investigated effects on screening knowledge and participation over 2 years. Methods We conducted a community-based, parallel-group, randomised controlled trial in Australia. Participants were women aged 48–50 years, without personal or strong family history of breast cancer, who had not undergone mammography in the past 2 years. We randomised 879 women to receive the intervention decision aid (evidence-based information on overdetection, breast cancer mortality reduction, and false positives) or control decision aid (identical but without overdetection information). We interviewed 838 women post-intervention and re-contacted them for follow-up at 6 months, 1 and 2 years. Main outcomes for this report are screening knowledge and participation. Results We interviewed 790, 746, and 712 participants at 6 months, 1, and 2 years, respectively. The intervention group demonstrated superior knowledge throughout follow-up. After 2 years, conceptual knowledge was adequate in 123 (34.4%) of 358 women in the intervention group compared with 71 (20.1%) of 354 controls (odds ratio = 2.04, 95% CI = 1.46 to 2.85). Groups were similar in total screening participation (200 [55.1%] vs 204 [56.0%]; odds ratio = 0.97, 95% CI = 0.73 to 1.29). Conclusions A brief decision aid produced lasting improvement in women’s understanding of potential consequences of screening, including overdetection, without changing participation rates. These findings support the use of decision aids for breast cancer screening.

Effects of awareness of breast cancer overdiagnosis among women with screen-detected or incidentally found breast cancer: a qualitative interview study

“…Randomised controlled trial data has shown that women can be safely informed about overdiagnosis before screening: educating women about overdiagnosis prior to screening improved understanding, reduced worry about breast cancer, and did not increase anxiety or reduce willingness to participate in breast screening. 18 This is consistent with other evidence showing that women value breast cancer screening and intend to participate in screening even when aware of the risk of overdiagnosis. 19 A systematic review on women’s values and preferences around breast cancer screening showed that women are willing to tolerate the potential harms of screening for an early diagnosis, but highlighted concern that women may not understand the concept of overdiagnosis.…”

“…However, this study shows the substantial negative impact of finding out about overdiagnosis after a diagnosis of breast cancer at least in some women. Randomised controlled trial data has shown that women can be safely informed about overdiagnosis before screening: educating women about overdiagnosis prior to screening improved understanding, reduced worry about breast cancer, and did not increase anxiety or reduce willingness to participate in breast screening 18. This is consistent with other evidence showing that women value breast cancer screening and intend to participate in screening even when aware of the risk of overdiagnosis 19.…”

Factors affecting intention to screen after being informed of benefits and harms of breast cancer screening: a study in 5 European countries in 2021

“…Prior research has investigated the effect of information on benefits and harms suggesting that, against a baseline of low awareness of the benefits and harms, this information increases knowledge, and informed choice [ 28 ], whereas, another study indicated that women becoming better informed about benefits and harms of breast screening may mean they are less likely to choose to participate [ 29 ]. Additionally, consistent with the findings of our study, informing about possible risks (such as overdiagnosis) does not affect intention to participate [ 30 – 33 ]. Some studies have indicated that an initial acceptance of harms may decrease over later screening rounds if knowledge about the risks of participation continues to increase from the baseline of low awareness [ 34 , 35 ].…”

Women’s perceptions of PERSPECTIVE: a breast cancer risk stratification e-platform

“…Results showed significant differences between groups with significantly more women in the intervention group meeting the threshold for enhanced knowledge and informed choice regarding screening post intervention [18]. These changes remained at the 2-year follow up [19].…”