It is known that drinking alcohol and taking hormone replacement therapy (HRT) can increase breast cancer risk.
A previous large study combined the two by looking at how drinking alcohol while taking HRT affected breast cancer risk.
The study confirmed that drinking alcohol increases estrogen levels and it is possible that the extra estrogen from drinking combined with the estrogen in HRT caused the dramatic increases in risk in this study.
However, in a more recent study, researchers from the Cancer Prevention Institute of California (CPIC) examined whether the increased breast cancer risk related to alcohol consumption in postmenopausal women was affected by the use of hormone therapy (HT), and found that after women stopped using HT, their risk of breast cancer was no longer elevated with moderate alcohol consumption.
The study, published in the electronic version of Cancer Epidemiology, Biomarkers & Prevention and based on information gathered from more than 40,000 participants in the California Teachers Study, found that while breast cancer risk was increased in postmenopausal women who consumed alcohol and were current HT users, it was not increased with alcohol consumption in women who had stopped using HT more than two years ago.
For the study, alcohol consumption was broken down into three groups: non-drinkers, drinkers consuming the equivalent of one drink per day and drinkers consuming the equivalent of two or more drinks per day. The study showed that HT use, when combined with alcohol consumption of two or more drinks per day, led to an approximately two-fold increase in risk over HT use alone. However, no significant increase was observed among former HT users, including those who had stopped taking HT less than three years earlier.
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