Alcohol & Cancer

We’ve downed a lot of merlot reassured that red wine may be healthful. But what’s the relationship between happy hour and cancer?

The very same thing that can make you feel like you’re the best karaoke singer in the room can, unfortunately, cause cancer. Studies of alcohol and cancer have been extensive, involving decades of research by scientists all over the world. Alcohol won’t cause every kind or case of cancer, but the evidence is convincing that alcohol has a causal role in many cancers of the digestive tract as well as breast cancer.

Dr. Christine Friedenreich, Senior Research Scientist and Epidemiologist with Alberta Health Services, points to an expert review conducted by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). “They conducted a comprehensive review of all of the world literature on this topic by cancer sites and concluded that there is now sufficient evidence that alcohol is related to an increased risk of several cancers,” she says. And the association between alcohol and cancer is not new. “They did a review in 1988 and already concluded then that alcohol increases cancer risk – but now the list of cancers affected by alcohol has increased as more studies have been done.”

The ingredient in alcohol responsible for the increase in risk is ethanol. Ethanol is created in the fermentation process: yeast breaks down the sugar in plant and grain into ethanol and carbon dioxide. The carbon dioxide is removed leaving ethanol and water. One drink contains about 10 to 15 grams of ethanol.

And fermentation creates the ethanol that’s in your after-work drink, no matter what’s being processed: grapes into wine, barley into beer or cane sugar into rum. Scientists have compared different alcoholic beverages to see which raises the risk of cancer. According to the World Cancer Research Fund (WCRF) and the American Institute for Cancer Research (AICR)’s publication, Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective, “[studies] show that it is alcoholic drinks in general – which is to say, the amount of ethanol consumed – that are or may be a cause of some cancers.”

Cancers most strongly associated to alcohol consumption include mouth, pharynx and larynx, oesophagus, colorectal in men and breast (both pre- and post-menopausal). There is also a probable effect on the liver and colorectal in women.

WCRF and AICR looked at thousands of different reports and studies before publishing their findings. For mouth, pharynx, and larynx alone they found five cohort studies, 89 case-control studies, and four ecological studies investigating alcoholic drinks. All reported an increased risk for cancer. The risk increases with the use of tobacco and the publication also points out, “high consumers of alcohol may also have diets low in essential nutrients, making tissues susceptible to carcinogenesis.” As with a lot of cancer – it’s complicated and teetotallers can also suffer the same cancers.

The risk of cancer that alcohol puts on your liver is harder to define. Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective reports, “It is biologically highly plausible that alcoholic drinks are a cause of liver cancer. In addition, regular high levels of alcohol consumption are known to cause liver damage. Tumour promotion has been linked to inflammation in the liver through alcohol-associated fibrosis and hepatitis.” Among carriers of the hepatitis C virus, even moderate alcohol consumption can worsen the infection. Hepatits C is prevalent among alcoholics with chronic liver disease and appears to accelerate the course of alcoholic liver disease.

The studies show increased risk of cancer with increased ethanol intake; in other words, the more you drink, the higher your risk. None of the studies reported a statistically significant decreased risk.

Social smokers, those people who only smoke when they’re drinking, might be doing more harm than they think. We often think that not being a regular smoker should give us less of a chance of cancer risk, but the mixture of the tobacco with alcohol actually causes a double whammy.

“It’s sobering how many cancers are affected,” Dr. Friedenreich says of the synergistic relationship between alcohol and tobacco. “If you’re exposed to alcohol and smoking you have an even higher risk of some cancers. And those would be aerodigestive cancers, in other words, cancers of the pharynx, larynx, oral cavity, esophagus, and colorectum.”

The WCRF and AICR report says that tobacco may induce specific mutations in DNA making them less efficiently repaired in the presence of alcohol. And alcohol can function as a solvent making it easier for the cancer-causing ingredients in smoking to penetrate our mucosal cells, damaging our bodies.

Wait – it gets confusing – didn’t we all raise a glass to studies that said we would have healthier hearts if we drank a little red wine?

Christine Friedenreich says some sources recommend that, if you drink at all, to limit your consumption to one or two drinks per day for women and one to three drinks daily for men. “But to be honest,” she says “seven to 14 drinks in a week is still pretty high.”

If there is benefit to cardiovascular health in drinking moderately, you may be negating it by increasing your cancer risk. The Heart and Stroke Foundation of Alberta, NWT and Nunavut advises people who want to positively impact their heart health to quit smoking, eat a healthy diet and do moderate- to vigorous-intensity aerobic activity for 150 minutes a week.

Drinking alcohol, like other decisions in life, comes down to personal choice. A glass of champagne at your daughter’s wedding or even a drunken weekend in Vegas won’t doom you to cancer, but cancer experts say there is no safe level of alcohol.

How much is one drink?

When you think about your daily limit for beer, wine or spirits, it’s important to know what constitutes a drink. According to the Canadian Public Health Association, one drink contains 13.6g of alcohol.

A standard drink is:

  • one 355 mL (12 oz) bottle of beer (5% alcohol)
  • one 146 mL (5oz) glass of wine (12% alcohol)
  • one 44 mL (1.5 oz) shot of spirits (40% alcohol)

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