Physical activity and the risk of breast cancer among Nigerian women.

BACKGROUND

Although physical activity has been associated with a reduced risk of breast cancer risk in high income countries (HIC), its role has not been widely studied in sub-Saharan Africa. Our aim was to investigate the association between physical activity (PA) and the risk of breast cancer in Nigeria.

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. Total PA was estimated by summing occupational, household, transport and leisure PA scores. PA was summarised as metabolic equivalents (MET) hours per week (MET-hr/wk). The putative association between breast cancer incidence and PA was analysed using multivariable logistic regression.

RESULTS

379 histologically confirmed breast cancer cases and 403 controls took part. Compared to women in the lowest categories, women in the upper middle category of total PA(adjusted OR-AOR 0.44, 95% CI: 0.27, 0.78),uppermost categories of total non-vigorous PA (AOR 0.26, 95%CI:0.09,0.75), household PA(AOR 0.0.38, 95% CI: 0.20, 0.71) and occupational PA (AOR 0.64, 95% 0.40, 1.02) had a reduced risk of breast cancer following adjustment for relevant confounders. Transport and leisure PA were not significantly associated with a reduced risk of breast cancer.

CONCLUSION

The total effect of various PA related to regular activities of Nigerian women was associated with a reduced risk of breast cancer. PA especially at household and occupational environments should be promoted as part of breast cancer prevention strategy in Nigeria.