21 September 2016 In Cancer

BACKGROUND: Breast cancer aetiology may differ by estrogen receptor (ER) status. Associations of alcohol and folate intakes with risk of breast cancer defined by ER status were examined in pooled analyses of the primary data from 20 cohorts.

METHODS: During a maximum of 6-18 years of follow-up of 1 089 273 women, 21 624 ER+ and 5113 ER- breast cancers were identified. Study-specific multivariable relative risks (RRs) were calculated using Cox proportional hazards regression models and then combined using a random-effects model.

RESULTS: Alcohol consumption was positively associated with risk of ER+ and ER- breast cancer. The pooled multivariable RRs (95% confidence intervals) comparing >/= 30 g/d with 0 g/day of alcohol consumption were 1.35 (1.23-1.48) for ER+ and 1.28 (1.10-1.49) for ER- breast cancer (Ptrend /= 0.26). Dietary (from foods only) and total folate intakes were not associated with risk of overall, ER+ and ER- breast cancer; pooled multivariable RRs ranged from 0.98 to 1.02 comparing extreme quintiles. Following-up US studies through only the period before mandatory folic acid fortification did not change the results. The alcohol and folate associations did not vary by tumour subtypes defined by progesterone receptor status.

CONCLUSIONS: Alcohol consumption was positively associated with risk of both ER+ and ER- breast cancer, even among women with high folate intake. Folate intake was not associated with breast cancer risk.

21 September 2016 In Cancer

This is the first study specifically estimating the proportion of new cancer cases that could be attributable to alcohol consumption in the year 2012 in Brazil. The proportion of exposed cases and the association between alcohol and lip and oral cavity, nasopharynx, other pharynx, larynx, esophagus, colorectum, female breast, liver, and intrahepatic bile ducts cancers was based on data made available by the Integrator System of Hospital Cancer Registries. The cancer incidence was obtained from the estimates produced by GLOBOCAN. In 2012 there were 437,592 new cancer cases in Brazil, excluding non-melanoma skin cancers. Of these, alcohol consumption was responsible for 4.8% of all new cases. The alcohol-attributable fraction was higher for men (7.0%) than for women (2.6%). A total of 21,000 new cancer cases, 15,554 in men and 5,646 in women, could be attributable to alcohol consumption. In Brazil, a significant fraction of cancer cases can be attributed to alcohol consumption, and public health measures to prevent heavy alcohol use should be implemented.

02 August 2016 In Cancer

BACKGROUND: Alcohol increases the risk of breast cancer even at moderate levels of intake. However, the relationship between alcohol consumption and mortality among breast cancer patients is less clear.

METHODS: This study included women from the Women's Health Initiative observational study and randomized trial diagnosed with breast cancer (n = 7,835). Cox proportional hazards regression was used to estimate adjusted HRs and 95% confidence intervals (CI) for overall and breast cancer-specific (BCS) mortality associated with drinking alcohol before or after a breast cancer diagnosis. We also assessed whether changes in drinking habits after diagnosis are related to mortality.

RESULTS: Women who were consuming alcohol prior to their breast cancer diagnosis had a nonstatistically significant 24% (95% CI, 0.56-1.04) reduced risk of BCS mortality and a 26% (95% CI, 0.61-0.89) reduced risk of all-cause mortality. Some variation was observed by estrogen receptor (ER) status as alcohol consumption was associated with a 49% (95% CI, 0.31-0.83) reduced risk of BCS mortality among ER- patients with no change in risk observed among ER+ patients (HR = 0.97; 95% CI, 0.31-1.54), though the difference between these risks was not statistically significant (P for interaction = 0.39). Postdiagnosis alcohol consumption, and change in consumption patterns after diagnosis, did not appear to be associated with all-cause or BCS mortality.

CONCLUSION: In this large study, consumption of alcohol before or after breast cancer diagnosis did not increase risks of overall or cause-specific mortality.

IMPACT: Coupled with existing evidence, alcohol consumption is unlikely to have a substantial impact on mortality among breast cancer patients. Cancer Epidemiol Biomarkers Prev; 1-6. (c)2016 AACR.

02 August 2016 In Cancer

BACKGROUND AND AIMS: There is increasing research evidence about the causal role of alcohol in cancer, accompanied by unclear and conflicting messages in the media. This paper aimed to clarify the strength of the evidence for alcohol as a cause of cancer, and the meaning of cause in this context.

METHODS: Recent epidemiological and biological research on alcohol and cancer was reviewed and summarized, drawing upon published meta-analyses identified from the Medline database and the archives of the International Agency for Research on Cancer. More recent epidemiological studies not included in these publications were also reviewed. A brief description of the nature of causal inference in epidemiology was used to frame discussion of the strength of the evidence that alcohol causes cancer, and contrast this with the case for a protective association of alcohol with cardiovascular disease.

RESULTS: The usual epidemiological understanding of a cause is a factor that increases the incidence of a condition in the population. In the context of a body of epidemiological evidence of an association of alcohol consumption with a disease, the inference that it is a causal association requires alternative explanations of the observed finding to be judged unlikely. Even without complete knowledge of biological mechanisms, the epidemiological evidence can support the judgement that alcohol causes cancer of the oropharynx, larynx, oesophagus, liver, colon, rectum and breast. The measured associations exhibit gradients of effect that are biologically plausible, and there is some evidence of reversibility of risk in laryngeal, pharyngeal and liver cancers when consumption ceases. The limitations of cohort studies mean that the true effects may be somewhat weaker or stronger than estimated currently, but are unlikely to be qualitatively different. The same, or similar, epidemiological studies also commonly report protection from cardiovascular disease associated with drinking but a high level of scepticism regarding these findings is now warranted.

CONCLUSIONS: There is strong evidence that alcohol causes cancer at seven sites in the body and probably others. Current estimates suggest that alcohol-attributable cancers at these sites make up 5.8% of all cancer deaths world-wide. Confirmation of specific biological mechanisms by which alcohol increases the incidence of each type of cancer is not required to infer that alcohol is a cause.

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