Screen-detected breast cancer and cancer stage by area-level deprivation: a descriptive analysis using data from the National Cancer Registry Ireland

Breast cancer screening programmes can lead to better disease outcomes, but women from deprived backgrounds are less likely to participate and more likely to present with late-stage cancer. This study aimed to explore associations between deprivation and breast cancer screening outcomes in Ireland during 2009-2018. Data on all female breast cancer cases diagnosed in Ireland during 2009-2018 were extracted from the National Cancer Registry Ireland. Associations between area-level deprivation, using the Pobal Haase-Pratschke deprivation index, and detection of breast cancer through BreastCheck, Ireland's breast screening programme, and stage of screen-detected breast cancer were explored. Unadjusted risk ratios (RRs) and 95% confidence intervals (CIs) were calculated. Among screening eligible women in Ireland in 2009-2018, there was no difference in risk of breast cancer detection through BreastCheck across deprivation quintiles (RR for most compared to least deprived group: 1.01, 95% CI: 0.96-1.06). In women with screen-detected breast cancer, the risk of late-stage cancer detection increased with deprivation in 2009-2013 (RR for most compared to least deprived group: 1.45, 95% CI: 1.10-1.93), but no association was observed between deprivation and cancer stage in 2014-2018. Notwithstanding its limitations, including the risk of confounding by uncontrolled variables, this study suggests screening eligible women in Ireland have had similar outcomes from breast cancer screening, regardless of deprivation level, since the national roll-out of BreastCheck. Associations between deprivation and screening outcomes should continue to be monitored to ensure Ireland's breast cancer screening programme is helping to reduce health inequities.