Abstract and Introduction
Abstract
Background: High participation in mammographic screening is essential for its effectiveness to detect breast cancers early and thereby, improve breast cancer outcomes. Breast density is a strong predictor of breast cancer risk and significantly reduces the sensitivity of mammography to detect the disease. There are increasing mandates for routine breast density notification within mammographic screening programs. It is unknown if breast density notification impacts the likelihood of women returning to screening when next due (i.e. rescreening rates). This study investigates the association between breast density notification and rescreening rates using individual-level data from BreastScreen Western Australia (WA), a population-based mammographic screening program.
Methods: We examined 981,705 screening events from 311,656 women aged 40+ who attended BreastScreen WA between 2008 and 2017. Mixed effect logistic regression was used to investigate the association between rescreening and breast density notification status.
Results: Results were stratified by age (younger, targeted, older) and screening round (first, second, third+). Targeted women screening for the first time were more likely to return to screening if notified as having dense breasts (Percentunadjusted notified vs. not-notified: 57.8% vs. 56.1%; P adjusted = 0.016). Younger women were less likely to rescreen if notified, regardless of screening round (all P < 0.001). There was no association between notification and rescreening in older women (all P > 0.72).
Conclusions: Breast density notification does not deter women in the targeted age range from rescreening but could potentially deter younger women from rescreening. These results suggest that all breast density notification messaging should include information regarding the importance of regular mammographic screening to manage breast cancer risk, particularly for younger women. These results will directly inform BreastScreen programs in Australia as well as other population-based screening providers outside Australia who notify women about breast density or are considering implementing breast density notification.
Introduction
Mammographic breast density, the white radiographic appearance of epithelial and stromal tissue on a mammogram, is a strong and established predictor of breast cancer risk.[1] Mammographic breast density also significantly reduces the sensitivity of mammography to detect the disease[2] as tumours also appear white on a mammogram and are hard to detect within dense breast tissue. There is currently no evidence-based screening recommendations for women with dense breasts and therefore many mammographic screening programs do not routinely record or report breast density to its participants. However, consumer advocates argue that women should be notified if they have dense breasts so they can discuss options, including supplemental screening if appropriate, with their doctors. As a result of consumer advocacy, there are increasing mandates for routine breast density notification in the United States and in Canada, and the Food and Drug Administration is currently working on prescribed language for federal breast density notification.
High participation in mammographic screening is essential for its effectiveness to detect cancers early and thereby, improve breast cancer outcomes. The literature regarding the effects of breast density notification on screening participation is sparse and mostly includes reports comparing summary outcomes before and after notification enactment, with no individual-level data. For example, comparisons of overall mammographic screening participation rates in California pre- and post-notification enactment, showed a decrease for women aged 40–70 (pre 82.4% vs. post 77.2%, P < 0.001).[3] In the state of New Jersey, a decrease in overall mammographic screening was also seen 18 months post enactment (pre-legislation 51.5% vs. post 48.5%).[4] Overall screening participation rates are known to fluctuate (e.g. due to changing demographics or media coverage), so only individual-level data can definitively determine whether breast density notification affects participation outcomes. There are currently no reports in the literature on whether breast density notification effects the likelihood of whether a woman returns to screening when next due (i.e. rescreening rates).
In Australia, mammographic screening is free for all women aged 40+ via population-based BreastScreen programs and women aged 50–74 are actively targeted for routine biennial screening (50–69 prior to July 1, 2013). The BreastScreen Western Australia (WA) program screens around 125,000 women each year and around 56% of women between the targeted ages of 50–74 years.[5] Age-standardized rescreening rates are ~ 50%, ~ 60%, and ~ 80% for women screened for the first time, second time, and in third/subsequent rounds, respectively.[5] Hence, despite the demonstrated benefits of free mammographic screening, half of women fail to return for routine mammography after their first screen. BreastScreen WA is currently the only state program that notifies women if they have dense breasts and have been doing so for over a decade. It is unknown if breast density notification impacts rescreening rates. Previous work investigating the impact of breast density notification on women's knowledge, psychosocial response and post-screening action[6–8] within BreastScreen WA demonstrated that ~ 91% of notified women indicated that they intended to rescreen again when next due (similar to that in controls, ~ 92%). However, empirical evidence of association is needed to directly inform state mammographic screening policy as well as provide important evidence to other breast cancer screening providers both nationally and internationally that either notify or are considering notifying women about breast density.
Therefore, using individual-level data from women who attended BreastScreen WA from 2008 to 2017, we examined rescreening rates by breast density notification status. We estimated the odds of rescreening for women who were notified they had dense breasts compared to those who were not notified, stratified by age group and screening round, and adjusted for other potential rescreening predictors.
Breast Cancer Res. 2022;24(5) © 2022 BioMed Central, Ltd.
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