Organized breast cancer screening not only reduces mortality from breast cancer but also significantly decreases disability-adjusted life years: analysis of the Global Burden of Disease Study and screening programme availability in 130 countries

BACKGROUND: Multiple studies over the past 4 decades have shown the significant benefit of breast cancer screening (BCS) in reducing mortality rates from breast cancer (BC). However, significant debate exists about the role of BCS in this regard, with some studies also showing no benefit in terms of mortality along with issues such as overdiagnosis, health care utilisation costs, psychological distress or overtreatment. To date, no BCS study has focused on disability. Hence the aim of this study is to evaluate the relative contribution of BCS approaches to age-standardized mortality and disability-adjusted life years (DALYs) rates along with other related risk factors, from a country-level perspective. 

PATIENTS AND METHODS: This study created a country-dataset by merging information from the Global Burden of Disease study regarding female age-standardized BC mortality, DALYs rates and other risk factors with the BCS programme availability at the national or regional level (versus no or only pilot such programme), BCS type (mammography, digital screening, breast self-examination and clinical breast examination) and other BCS-related information among 130 countries. Mixed-effect multilevel regression models were run to examine the associations of interest. 

RESULTS: The most important factor predictive of lower mortality was the more advanced type of BCS programme availability [mammography: -4.16, 95% CI -6.76 to -1.55; digital mammography/ultrasound: -3.64, 95% CI -6.59 to -0.70] when compared with self- or clinical breast examinations. High levels of low-density lipoprotein cholesterol (LDL-c) and smoking were also related to higher mortality and DALYs from BC. In terms of BC DALYs, BCS had a 21.9 to 22.3-fold increase in the magnitude of effect compared with that in terms of mortality. Data on mortality and DALYs in relation to BCS programmes were also calculated for high-, middle- and low-income countries. 

CONCLUSIONS: These data further support the positive effects of BCS in relation to age-standardized BC mortality rates, and for the first time show the impact of BCS on DALYs too. Additional factors, such as diabetes, high levels of LDL-c or smoking seemed to be related to BC mortality and disability, and could be considered as additional components of possible interventions to be used alongside BCS to optimize the BCS benefit on patients.