ABSTRACT & COMMENTARY
Coffee and Tea Consumption and the Risk of Invasive Breast Cancer in Postmenopausal Women Results from a prospective, observational study
By Lindsay Adrian, ND, FABNO
REFERENCE
Zheng KH, Zhu K, Wactawski-Wende J, et al. Caffeine intake from coffee and tea and invasive breast cancer incidence among postmenopausal women in the Women’s Health Initiative [published online ahead of print, 2021 Aug 21]. Int J Cancer. 2021;10.1002/ ijc.33771. doi:10.1002/ijc.33771 STUDY OBJECTIVE
To determine if there is an association between caffeine intake from coffee or tea and the formation of invasive breast cancer in postmenopausal women
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The positive or negative connections between coffee and tea consumption and cancer risk in general
DESIGN
Prospective, observational study PARTICIPANTS
The Women’s Health Initiative (WHI) recruited close to 100,000 women from 1993 to 1998 to participate in their observational study. Of these, 79,871 racially and ethnically diverse women from 40 centers across the United States were included in the present study. They were postmenopausal at recruitment and ranged in age from 50 to 79 years. Investigators excluded women from the present analysis if they had a history of cancer or had cancer at the onset of the study. STUDY PARAMETERS ASSESSED
In an annual survey, the study participants were asked questions about their intake of caffeinated and decaffeinated coffee and tea, with participants noting either none, 1 cup, 2 to 3 cups, 4 to 5 cups, or 6 or more cups. Caffeine intake from other sources was not included and is not part of this study. The original study was conducted with the annual survey over a 10-year period; however, there were 2 additional 5-year extension studies
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have long been debated.
encompassing up to September 2015. Data were also collected on age, race, ethnicity, education, smoking status and intensity, alcohol consumption and frequency, sleep duration, exercise, caloric intake, hormone therapy history, age at menarche, age at menopause, age at first full-term birth, parity, and family history of breast cancer. Further, a healthy eating questionnaire was used, and body mass index (BMI) was calculated from the height and weight collected by investigators. PRIMARY OUTCOME MEASURES
The incidence of invasive breast cancer, with data collected including hormone receptor status, HER2 (human epidermal growth factor receptor 2) receptor status, stage, grade, size, tumor type, nodal status, and histology. Investigators put these outcomes through multivariable analysis using covariates in groups of demographic variables (age, race, ethnicity, and education), lifestyle variables (smoking, alcohol, caloric intake, exercise, healthy eating scores, BMI, and sleep
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duration), and reproductive variables (hormone therapy use, menarche, menopause, age at first birth, parity, and family history of breast cancer). KEY FINDINGS
When investigators accounted for all of the variables, they observed no significant associations between risk of invasive breast cancer and consumption of various amounts of caffeine through coffee or tea consumption. The lack of association was maintained when data were isolated for receptor subtypes, grade, stage, and histology. In subgroup analysis, participants who drank 2 to 3 cups per day of decaffeinated coffee had an increased risk of hormone receptor–positive cancer; however, this was no longer statistically significant after accounting for multiple comparisons. There was a statistical significance in the heterogeneity of tea intake between hormone receptor status (ER positive vs negative) and histological subtype (ductal vs lobular). (continued on page 12)
