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Prospective study of breast cancer in relation to coffee, tea and caffeine in Sweden
Author(s) -
Oh JinKyoung,
Sandin Sven,
Ström Peter,
Löf Marie,
Adami HansOlov,
Weiderpass Elisabete
Publication year - 2015
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.29569
Subject(s) - medicine , caffeine , breast cancer , relative risk , poisson regression , confounding , confidence interval , prospective cohort study , lower risk , incidence (geometry) , cancer , gynecology , demography , environmental health , population , physics , sociology , optics
Studies of coffee and tea consumption and caffeine intake as risk factors for breast cancer are inconclusive. We assessed coffee and tea consumption, caffeine intake, and possible confounding factors among 42,099 women from the Swedish Women's Lifestyle and Health study, the participants of which were aged 30–49 years at enrollment in 1991–1992. Complete follow‐up for breast cancer incidence was performed through 2012 via linkage to national registries. Poisson regression models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for breast cancer. During follow‐up 1,395 breast cancers were diagnosed. The RR was 0.97 (95% CI 0.94–0.99) for a 1‐unit increase in cups of coffee/day, 1.14 (95% CI 1.05–1.24) for a 1‐unit increase in cups of tea/day, and 0.97 (95% CI 0.95–1.00) for a 100 mg/day increase in caffeine intake. Although the RR for no consumption (RR = 0.86, 95% CI 0.69–1.08), a group with a relatively small number of women, was not statistically significant, women with higher consumption had a decreased breast cancer risk (3–4 cups/day: RR = 0.87, 95% CI 0.76–1.00; ≥5 cups/day: RR = 0.81, 95% CI 0.70–0.94) compared to women consuming 1–2 cups of coffee/day. Compared to no consumption, women consuming >1 cups tea/day showed an increased breast cancer risk (RR = 1.19, 95% CI 1.00–1.42). Similar patterns of estimates were observed for breast cancer risk overall, during pre‐ and postmenopausal years, and for ER+ or PR+ breast cancer, but not for ER− and PR− breast cancer. Our findings suggest that coffee consumption and caffeine intake is negatively associated with the risk of overall and ER+/PR− breast cancer, and tea consumption is positively associated with the risk of overall and ER+/PR+ breast cancer.