Benign breast disease and breast cancer risk in African women: a case–control study

Purpose To examine the association between benign breast disease (BBD) and breast cancer (BC) in a heterogeneous population of African women. Methods BC cases and controls were enrolled in three sub-Saharan African countries, Nigeria, Cameroon, and Uganda, between 1998 and 2018. Multivariable logistic regression was used to test the association between BBD and BC. Risk factors dually associated with BBD and BC were selected. Using a parametric mediation analysis model, we assessed if selected BC risk factors were mediated by BBD. Results Of 6,274 participants, 55.6% (3,478) were breast cancer cases. 360 (5.7%) self-reported BBD. Fibroadenoma (46.8%) was the most commonly reported BBD. Women with a self-reported history of BBD had greater odds of developing BC than those without (adjusted odds ratio [aOR] 1.47, 95% CI 1.13–1.91). Biopsy-confirmed BBD was associated with BC (aOR 2.25, 95% CI 1.26–4.02). BBD did not significantly mediate the effects of any of the selected BC risk factors. Conclusions In this study, BBD was associated with BC and did not significantly mediate the effects of selected BC risk factors.