Background: Alcohol drinking is linked to the development of breast cancer. However, there is little knowledge about the impact of alcohol consumption on breast cancer risk among African women.

Methods: We conducted a case-control study among 2,138 women with invasive breast cancer and 2,589 controls in Nigeria, Cameroon, and Uganda from 1998 to 2013. A structured questionnaire was used to collect information on alcohol consumption, defined as consuming alcoholic beverages at least once a week for six months or more. Logistic regression was used to estimate adjusted odds ratio (aOR) and 95% confidence interval (CI).

Results: Among healthy controls, the overall alcohol consumption prevalence was 10.4%, and the prevalence in Nigeria, Cameroon, and Uganda were 5.0%, 34.6%, and 50.0%, respectively. Cases were more likely to have consumed alcohol (aOR = 1.62, 95% CI: 1.33–1.97). Both past (aOR = 1.54; 95% CI: 1.19–2.00) and current drinking (aOR = 1.71; 95% CI: 1.30–2.23) were associated with breast cancer risk. A dose-response relationship was observed for duration of alcohol drinking (P-trend <0.001), with 10-year increase of drinking associated with a 54% increased risk (95% CI: 1.29–1.84).

Conclusion: We found a positive relationship between alcohol consumption and breast cancer risk, suggesting that this modifiable risk factor should be addressed in breast cancer prevention programs in Africa.