Yaghjyan L, et al. - The links between coffee consumption and postmenopausal breast cancer risk were investigated, overall and by the status of postmenopausal hormone therapy (PMH). In women who used hormones in the past, an association might be seen between coffee consumption and increased risk of breast cancer.

• A total of 126,182 postmenopausal women (2,636 with breast cancer and 123,546 without) from UK Biobank were included.
• Via the linkage to the UK National Health Service Central Registers, cancer diagnoses were ascertained.
• At baseline, researchers gathered information on breast cancer risk factors and coffee consumption, which was updated during follow-up.
• Using Cox proportional hazards regression, they assessed the links between coffee consumption and breast cancer, overall and in stratified analyses by woman’s PMH status (none, past, current).

• In the overall analysis, coffee consumption was not found to be related to breast cancer risk (Hazard Ratio [HR] 1.00, 95% CI 0.91–1.11 for 2–3 cups/day, and HR 0.98, 95% CI 0.87–1.10 for ≥ 4 cups/day, p-trend = 0.69).
• Relative to those who consumed < 7 cups/week, a 16% reduced risk of breast cancer was noted in women with no PMH history who consumed ≥ 4 cups/day (HR 0.84, 95% CI 0.71–1.00).
• Among women with past PMH, a 22% greater risk of breast cancer was seen in those consuming ≥ 4 cups/day vs those consuming < 7 cups/week (HR 1.22, 95% CI 1.01–1.47).
• Among current PMH users, no link was found.
• No significant interaction was found between PMH and coffee consumption (p=0.24).