Socio-economic status and the risk of breast cancer among Nigerian women: a case control study.

Introduction: an increased risk of breast cancer associated with high socio-economic status has been reported in high income countries. A few available African studies have reported inconsistent findings using different single socio-economic measures. Our aim was to investigate the association between socio-economic status and the risk of breast cancer among Nigerian women based on a range of socio-economic status measures.

Methods: we conducted a hospital-based case-control study involving participants from five hospitals in Lagos and Abuja. Women were interviewed in-person between October 2016 and May 2017 using a semi-structured questionnaire. Socio-economic status was assessed based on education, occupation, income, wealth, and socio-economic index. Multivariable logistic regression was applied in data analysis using Statistical Package for Social Sciences (SPSS) version 23. Level of significance was based on 95% confidence interval or p-values less than 0.05.

Results: we recruited 379 histologically confirmed breast cancer cases and 403 controls. Following full adjustments, breast cancer risk reduced as socio-economic index increased (p for trend=0.028). Although women in the highest categories of educational attainment [Odds ratio (OR)=0.21, 95% confidence interval (CI): 0.09, 0.53], and personal income (OR=0.37, 95% CI: 0.19, 0.72) had a reduced risk of breast cancer compared to women in the lowest categories respectively after adjustments for relevant covariates, income alone exhibited a significant risk reduction following mutual adjustment for other socio-economic status measures (p for trend=0.014).

Conclusion: the observed associations between high socio-economic status and lower breast cancer risk in Nigeria contrast with predominant findings in high-income countries. It suggests the need for socio-economic intervention and other preventive programmes such as improved access to screening and diagnostic services targeted at women of low socio-economic status in Nigeria.