Does alcohol cause cancer?

Question

The latest Cancer Council of Australia claims that alcohol "probably caused about 5.6 per cent of cancers in Australia" and that there is no safe amount of alcohol to consume.

http://www.smh.com.au/lifestyle/wellbeing/quit-drinking-to-cut-cancer-risk-20110501-1e38g.html

That sounds extremely high. Especially since I didn't even know alcohol was related to cancer at all (in fact, I was always told a glass of wine during a meal is good for you). Can someone find any other sources for or against this claim?

Answer 1

Since the link you posted explicitly mentions bowel and breast cancer I'll focus on those.

This study (2007) is about increased bowel cancer risk:

We conducted a meta-analysis of prospective cohort studies published between 1990 and June 2005 on the relationship between alcohol intake and colon and rectal cancer.

High alcohol intake was significantly associated with increased risk of colon and rectal cancer when comparing the highest with the lowest category of alcohol intake, equivalent to a 15% increase of risk of colon or rectal cancer for an increase of 100 g of alcohol intake per week.

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Here (2007) is a meta-analysis of studies of alcohol and breast cancer:

98 unique studies were included, involving 75,728 and 60,653 cases in drinker versus non-drinker and dose-response analyses, respectively.

... we confirm the alcohol-breast cancer association. We compared our results to those of an individual patient data analysis, with similar findings. We conclude that the association between alcohol and breast cancer may be causal.

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Here is a study that looked into "moderate alcohol intake and cancer incidence in women":

A total of 1,280,296 middle-aged women in the United Kingdom enrolled in the Million Women Study were routinely followed for incident cancer.

Low to moderate alcohol consumption in women increases the risk of certain cancers.

For every additional drink regularly consumed per day, the increase in incidence up to age 75 years per 1000 for women in developed countries is estimated to be about

• 11 for breast cancer,
• 1 for cancers of the oral cavity and pharynx,
• 1 for cancer of the rectum,
• 0.7 each for cancers of the esophagus, larynx and liver,

giving a total excess of about 15 cancers per 1000 women up to age 75.

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But I also found a study that suggests that alcohol could reduce the risk of kidney cancer:

We performed a pooled analysis of 12 prospective studies that included 530,469 women and 229,575 men with maximum follow-up times of 7-20 years.

Moderate alcohol consumption was associated with a lower risk of renal cell cancer among both women and men in this pooled analysis.

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I also suggest taking a look at the "Is alcohol beneficial in small amounts?" question.

Answer 2

I suggest you read the current WHO report on Alcohol and Health 2011.

Look for example at page 26, Figure 12: Alcohol abuse is the main cause of liver cancer (which can develop following liver cirrhosis) in the Western World (in other places it's still Hepatitis B). Other cancers linked to alcohol consumption are esophageal cancer, mouth and oropharynx cancer, and a few others (colon cancer, breast cancer) where it appears to be a risk factor, too.

Quoting from the same report (p. 20):

Cancer: alcohol consumption has been identified as carcinogenic for the following cancer categories (Baan et al., 2007): cancers of the colorectum, female breast, larynx, liver, oesophagus, oral cavity and pharynx. The higher the consumption of alcohol, the greater the risk for these cancers: even the consumption of two drinks per day causes an increased risk for some cancers, such as breast cancer (Hamajima et al., 2002).

I haven't found a concrete reference to "5 % of all cancers in Australia", but it seems at least plausible. According to the WHO report, 21.6 % of all alcohol-attributable deaths are caused by cancer (p. 26). In Australia, alcohol appears to be the underlying risk factor responsible for 2-4.9 % of deaths (p. 27), and not all cancers are fatal, of course. So we're at least in the same ballpark...

Answer 3

I can tell you that my dentist advised me to use mouthwash twice a day to destroy bacteria that causes gum disease. He also said to rinse with water afterwards to mitigate any carcinogenic effects the mouthwash might have.

Still, I did some research and found this study, which suggests that alcohol in mouthwash does not cause cancer. It adds a footnote about potable alcohol:

Results. The results of six of the studies reviewed are negative and provide no support for the hypothesis that use of alcohol-containing mouthwash increases the risk of OPC. One of the three studies with positive results was a case series and included a follow-up case-control study, the results of which were negative. The authors reanalyzed the study with the most positive results. This analysis found that the study results were just as positive for nonmucosal cancers developing in the mouth as they were for the usual type of OPC. The authors concluded that this study’s positive finding resulted from recall bias.

Clinical Implications. It is unlikely that the use of mouthwashes that contain alcohol increases the risk of developing OPC.

The excessive consumption of alcohol-containing beverages, or ACBs, moderately increases risks of cancers of the mouth, pharynx, larynx, esophagus and liver.**1 ACBs also interact with cigarette smoking to increase greatly the risk of several of these cancers.2 However, alcohol (ethanol) is not carcinogenic in animals,3 and only its prolonged abuse in humans is related to hepatocellular carcinoma, or HCC. Indeed, the causal nature of the ACB-HCC association has been questioned.4

So while the point remains open for further study, it does not appear that you should fear drinking in moderation. Or using mouthwash.