Occupation and Female Breast Cancer Mortality in South Africa: A Case–Control Study

Highlights: Public health relevance—How does this work relate to a public health issue? Breast cancer is a major cause of cancer-related deaths in South Africa, and the findings presented in this study illustrate the occupational determinants that contribute to cancer mortality. The study links different occupational groups to breast cancer mortality using national data. Public health significance—Why is this work of significance to public health? This is the first national study demonstrating that occupation is a potential independent predictor of breast cancer mortality in South Africa after adjusting for key demographic and behavioural factors. The results show elevated mortality risks among specific occupational groups, indicating that workplace factors do in fact play a role in breast cancer outcomes. Public health implications—What are the key implications or messages for practitioners, policy makers and/or researchers in public health? Occupational information should be incorporated when assessing patients for breast cancer prevention and screening programmes with targeted interventions for high-risk occupational groups. Researchers should prioritise research into occupational exposures and working conditions to provide an evidence base for breast cancer control. Breast cancer is the most frequently diagnosed malignancy among South African women and remains a leading cause of cancer-related death, yet the role of occupation as an independent predictor of mortality has not been evaluated nationally. In this unmatched case–control study using 2011–2019 mortality data, we compared 13,207 breast cancer deaths with 64,849 non-malignant circulatory disease deaths among women aged 30 years and older, classifying usual occupation into major and sub-groups. A multivariable binary logistic regression adjusting for age, year of death, education, province of death and smoking status was conducted. We observed that compared with elementary occupations, breast cancer mortality was significantly higher during 2011–2015 among legislators, senior officials and managers (aMOR = 1.79, 95% CI: 1.36–2.36), clerks (aMOR = 1.75, 95% CI: 1.46–2.11), professionals (aMOR = 1.62, 95% CI: 1.36–1.94), craft and related trades workers (aMOR = 1.55, 95% CI: 1.18–2.05), technicians and associate professionals (aMOR = 1.54, 95% CI: 1.21–1.96), and service workers, shop and market sales workers (aMOR = 1.33, 95% CI: 1.10–1.62), with similar patterns persisting in 2016–2019 where technicians and associate professionals (aMOR = 1.69, 95% CI: 1.44–1.98), legislators, senior officials and managers (aMOR = 1.59, 95% CI: 1.20–2.10), professionals (aMOR = 1.47, 95% CI: 1.23–1.75), clerks (aMOR = 1.43, 95% CI: 1.24–1.65), and service workers (aMOR = 1.34, 95% CI: 1.12–1.61) again showed elevated odds. The sub-occupation analyses for 2011–2015 identified strikingly high risks among building and related trades workers excluding electricians (aMOR = 8.01, 95% CI: 3.06–20.96), legal, social and cultural professionals (aMOR = 3.32, 95% CI: 2.18–5.04), and business and administration professionals (aMOR = 2.18, 95% CI: 1.60–2.97). The results underscore occupation as an essential determinant of breast cancer mortality, highlighting the need for targeted prevention and screening strategies in workers.