Despite extensive investigation of the association between alcohol consumption and breast cancer risk, the effect of low-to-moderate alcohol intake on breast cancer has been inconsistent.
A case control study was conducted in China in 2004-2005 to examine the association by menopausal status, oestrogen (ER) and progestorone receptor (PR) status of the tumour. There were 1009 incident cases with histologically confirmed breast cancer and 1009 age-matched controls were recruited. The study assessed alcohol consumption by face to face interview using a validated questionnaire and obtained tumour ER and PR status from pathology reports.
Low to moderate alcohol consumption was inversely associated with breast cancer risk. Compared with non-drinkers, the adjusted odds ratios (ORs) for alcohol <5g per day were 0.41 (95% confidence interval 0.27-0.62) and 0.62 (0.48-0.79) in postmenopausal and premenopausal women, respectively. The inverse association was consistent for alcohol <15g per day across hormone receptor status groups with ORs of 0.36-0.56 in post menopausal women and 0.57-0.64 in premenopausal women. An exception was that alcohol greater than or equal to 15g per day appeared to increase the risk of breast cancers with discordant receptor status in postmenopausal women, that is ER+/PR- or ER-/PR+, 4.37(1.56-11.65).
The study found that low to moderate intake was not associated with increased risk of breast cancer in pre- or postmenopausal Chinese women. The authors suggest that future studies are required to understand differences in effect of alcohol in breast cancers by tumour hormone receptor status.
Source: Low-to-moderate alcohol intake and breast cancer in Chinese women M Zhang and C D J Holman British Journal of Cancer, 9 August 2011.