ABSTRACT

Background and aims:
Coffee and caffeine consumption have been widely investigated for their potential effects on cancer risk, driven by their bioactive compounds and antioxidant properties. However, findings on the association between them and breast cancer risk remain inconsistent across studies. This study aimed to conduct a systematic review and meta-analysis to examine the association between coffee, decaffeinated coffee, and caffeine intake and the risk of breast cancer.

Methods:
A literature search was conducted in databases from inception through 1st February 2026 to identify relevant cohort studies. Meta-analyzes were performed using the RRs with 95% confidence intervals (95% CI) as effect measures.

Results:
Thirty-one cohort studies were included. Regular coffee consumption was associated with a modest reduction in breast cancer risk among women (pooled HR: 0.95; 95% CI: 0.91-0.99; p = 0.035), particularly in postmenopausal populations. In contrast, no significant associations were observed for caffeine intake (HR: 0.99; 95% CI: 0.94-1.04; p = 0.824) or decaffeinated coffee consumption (HR: 1.00; 95% CI: 0.94-1.07; p = 0.793). Subgroup analyzes by menopausal status, cohort duration, and hormone receptor subtype yielded consistent null results across both caffeine- and decaffeinated-coffee categories.

Conclusion:
This meta-analysis indicates that while caffeine and decaffeinated coffee intake are not significantly associated with breast cancer risk, regular coffee consumption may offer a modest inverse association, especially among postmenopausal women. The findings highlight the potential influence of bioactive compounds in coffee beyond caffeine on breast cancer development. Further large-scale prospective studies are needed to substantiate these results and elucidate underlying biological pathways.

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