Household, Moderate Physical Activity and the Risk of Breast Cancer Among Nigerian Women: An Epidemiological Study

Background: Breast cancer incidence in Nigeria has risen by >120% since 2000. The mortality rate (25.9/100,000/yr) ranks highest in Africa. Inverse associations between household physical activities (PA) as well as moderate PA, and breast cancer risk have been suggested in literature. However, the roles of these activities in breast cancer risk have not been widely studied in Africa. As the socioeconomic status of many Nigerian women improves, their household and daily routines are expected to change. These have implications for their level of physical activity. Aim: The aim of this study was to investigate if there is an association between household, as well as moderate PA and breast cancer risk among Nigerian women. Methods: The study was a multisite hospital based case-control design involving 379 histologically confirmed breast cancer cases and 403 controls. The participants aged ≥ 20 years were interviewed in-person between October 2016 and May 2017 using a pretested questionnaire. Cases were selected from oncology wards and controls from ophthalmology wards. Self-reported household and moderate PA were summarized as both hours per week and metabolic equivalents (MET) hours per week (met-hr/wk). Data were analyzed using multivariable logistic regression, adjusting for known confounders. SPSS version 23 was used for all analyses. Results: The odd of having breast cancer (based on MET-hr/wk) was 40% less among women in the upper tertile of household PA than those in the lowest tertile (95% CI, 0.39-0.94). This was stronger among younger (OR: 0.50, 95% CI, 0.26-0.94), premenopausal (OR: 0.46; 95% CI, 0.24-0.89) and lean women (OR: 39, 95% CI, 0.16-0.87). Moderate PA was also associated with reduced breast cancer risk ( P = 0.04). Conclusion: The study suggested that household and moderate physical activities were protective of breast cancer among Nigerian women. Household chores and other routine moderate activities could provide opportunities for breast cancer prevention in Nigeria. Future studies could consider the use of community controls to authenticate the findings.