Alcohol Consumption by Beverage Type and Risk of Breast Cancer

A Dose-Response Meta-Analysis of Prospective Cohort Studies

Qiuyu Sun; Weihong Xie; Yanli Wang; Feifei Chong; Mengmeng Song; Tiandong Li; Linping Xu; Chunhua Song

Disclosures

Alcohol Alcohol. 2020;55(3):246-253. 

In This Article

Discussion

This meta-analysis summarizes 22 observational studies and encompassed a total of 45,350 breast cancer cases, investigating the association between different alcoholic beverages and breast cancer incidence. We found that there is a continuous positive correlation between total alcohol intake and breast cancer incidence. With every 20 g total alcohol increase, the magnitude of the estimated relative risk ranged from a 22% (95%CI = 1.17–1.27) increase in breast cancer to 23.3% (95%CI = 1.18–1.29) increase in postmenopausal breast cancer. For alcohol type, every extra 20 g/day ethanol in wine increased the incidence by 18.6% (95%CI = 1.08–1.30). We found no statistical evidence for beer and spirits specifically, perhaps because of the limited sample size.

Our conclusion supported the previous studies and meta-analysis of observational epidemiological studies (Corrao et al., 2004; Coronado et al., 2011; Li et al., 2011; Gao et al., 2013) of alcohol intake and the incidence of breast cancer. Choi et al.'s cohort meta-analysis (Choi et al., 2018) of 135 articles searched for light total alcohol drinking and cancer risk and concluded that ≦1 drink/day increased the risk of cancer of female breast. The WCRF/AICR study (Nomura et al., 2016) finds that higher adherence to the recommendation to limit alcohol drinks was moderately associated with lower risk of postmenopausal breast cancer in the overall cohort. Furthermore, the 2015 newly revised ECAC fourth edition (Scoccianti et al., 2016) also changed its recommendation on drinking from "Moderate your consumption to two drinks per day if you are a man or one drink per day if you are a woman" to "Not drinking is better for cancer prevention". Nevertheless, Chen et al. (2016) included case-control studies and cohort studies and showed that the risk decreased for women who consumed alcohol below 10 g ethanol [<1 standard drink] per day. The risk declined to the bottom at the threshold of 5 g/d of ethanol, respectively, which is inconsistent with ours. They did not consider the difference in findings between case-control studies and cohort studies and drew a perhaps untrustworthy conclusion based on the findings from combining the results of both case-control studies and cohort studies (Choi et al., 2018).

In our study using only cohort data, both total alcohol and wine intake and even light drinking were associated with increased risk of breast cancer. Its incidence was increased at the level of > 1 g per day in total alcohol or wine, especially for postmenopausal breast cancer where the risk increased by 1.05% every 1 g/day. Furthermore, the risk of current total alcohol versus none is the highest in ER+/PR+ breast cancer. However, except for total alcohol and wine consumption, there was not sufficient evidence to support the relationship between beer and spirit intake and breast cancer risk.

There are some possible mechanisms explaining the association between alcohol consumption and the risk of breast cancer. Alcohol consumption has been shown to promote mammary tumor growth and insulin sensitivity (Hong et al., 2010). Alcohol promotes breast cancer cell invasion by regulating the Nm23-ITGA5 pathway (Wong et al., 2011). Other research (Wang et al., 2017) found p38γ MAPK siRNA significantly inhibited an alcohol-induced increase in CSC population, mammosphere formation and migration/invasion of breast cancer cells overexpressing ErbB2 which could lead to the development of breast cancer. The increase in postmenopausal and ER+/PR+ breast cancer risks with alcohol intake can be explained by the associated increase in estrogen production, as high alcohol intake has been previously shown to be an enhancer of estrogen synthesis (Ginsburg et al., 1996; Purohit, 1998).

The ARP (20.63%) calculated for Europe was noticeably higher than North America (13.04%) and Asia (11.50%). According to the WHO (2018), the highest levels of per capita alcohol consumption are observed still in the European Region though the percentage of drinkers has recently decreased. The contrasting increase in current drinkers in the Western Pacific Region is dominated by China: 4.1, 7.1 and 7.2 l in 2005, 2010 and 2016, respectively. This suggests that the incidence of breast cancer in China may continue to rise.

Some papers (Dixon et al., 2015; Martin et al., 2017) report the demographic impact of the mass media alcohol and cancer campaigns and find that mass media campaigns can raise awareness of the harm caused by alcohol, help inform consumer decision-making and satisfy consumers' right to information. Therefore, by understanding the impact of different types of alcohol on breast cancer, relevant departments can further carry out corresponding publicity campaigns for the type of drinking.

The strengths of this meta-analysis should be acknowledged in this report. All selected articles are prospective cohort studies, so the potential recall bias was avoided. Selected studies met inclusion criteria, which provided sufficient power to assess the association. Furthermore, dose–response relationships and attribute risk were performed to increase the authenticity and reliability of alcohol consumption on the development of breast cancer.

Although the meta-analysis is robust, there are also some limitations. Firstly, statistical analysis showed significant heterogeneity and even conducted subgroup analysis, probably because of the difference in research protocols, survey methods, or research standards of each study, which would impact the effect of alcohol consumption on the development of breast cancer. Secondly, only 22 articles were included in the study, and even in the same area, the incidence of breast cancer still varies greatly.

In conclusion, total alcohol consumption was associated with an increased risk of breast cancer especially for postmenopausal and ER+/PR+ breast cancer, and wine itself gives a similar result. Moreover, the study observed that breast cancer incidence in European alcohol drinkers had a higher attributable percentage to alcohol compared to pooled estimates in North America and Asia. Public health authorities should be aware of the interactions between alcohol and other factors in breast cancer.

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