Alcohol and Cancer in the spotlight

Studies in Europe and Australia confirm alcohol as a cause of cancer, but role of moderate drinking controversial

Almost one in ten (9.6%) cancers in men and 3% of cancers in women in Western Europe are caused by former and current alcohol consumption, according to a paper published in the British Medical Journal. Another analysis, from the new Cancer Council of Australia, published in the Medical Journal of Australia, shows the level of cancer incidence caused by alcohol in Australia is higher than previously believed, with one in five breast cancers being linked to alcohol. The Cancer Council concludes that “alcohol is clearly one of the most carcinogenic products in common use” and, like the main author of the European study, recommends abstinence from alcohol to reduce the risk of cancer. However, critics of the European study argue that its results actually show that moderate drinking plays only a relatively small role in cancer, and that most of the cases of cancer attributable to alcohol arise from levels of consumption in excess of recommended ‘sensible limits’.

Cancer in Australia

The new analysis shows the level of cancer incidence caused by alcohol in Australia is higher than previously thought, with more than 5000 new cases each year linked to long-term drinking. Applying the latest international data to Australia, the analysis estimated that 22 % of the nation’s breast cancer cases were linked to alcohol consumption. It also factored in new evidence linking alcohol to bowel cancer in men.

The Cancer Council of Australia has now published a position statement on alcohol and cancer which recommends abstinence from alcohol in order to reduce the risk of cancer. The main recommendations on alcohol use are:

Alcoholic drinks and ethanol are carcinogenic to humans. There is no evidence that there is a safe threshold of alcohol consumption for avoiding cancer, or that cancer risk varies between the type of alcoholic beverage consumed.

Cancer Council recommends that, to reduce their risk of cancer, people limit their consumption of alcohol, or better still avoid alcohol altogether. For individuals who choose to drink alcohol, consumption should occur within the Australian National Health and Medical Research Council (NHMRC) guidelines.

The Chief Executive Officer of Cancer Council Australia, and a co-author of the analysis, Professor Ian Olver, said community awareness of the links between alcohol and cancer should be raised so people could make more informed lifestyle choices to help minimise their cancer risk.

“We have known for some time that alcohol is a major risk factor for breast cancer, but only by applying international data to Australian drinking patterns were we able to estimate that more than one in five cases here are linked to alcohol,” Professor Olver said. “Factor in the new evidence on bowel cancer in men and the established links to cancers of the mouth, pharynx, larynx, oesophagus and liver, and alcohol is clearly one of the most carcinogenic products in common use.”

Professor Olver said the impact on breast cancer was a particular concern, as there were few other steps women could take to minimise their risk. “A lot of effort goes into raising breast cancer awareness, but how many Australian women are aware that reducing alcohol consumption is one of the best ways to reduce their breast cancer risk?” he said. Professor Olver said the dose-response relationship meant the risk of alcohol-related cancer increased with every drink consumed. “The more alcohol you consume over time, the higher your risk of developing an alcohol-related cancer. So if individuals do choose to drink, our advice is to do so in accordance with the National Health and Medical Research Council guidelines, which recommend no more than two standard drinks a day.”

Alcohol and Cancer in Europe

The figures for cancers caused by alcohol in Europe are based on risk estimates from the European Prospective Investigation into Cancer (EPIC) Study and representative alcohol consumption data compiled by the World Health Organization (WHO). The study focuses on France, Italy, Spain, United Kingdom, the Netherlands, Greece, Germany and Denmark. In the EPIC Study 363,988 men and women, mostly aged between 35 and 70 years at the time of recruitment were followed for cancer since the mid 1990s. The participants completed a detailed questionnaire on diet and lifestyle at entry into the study. Alcohol consumption was measured by specific questions on the amount, frequency and type of beverage that was consumed at present and in the past.

According to the International Agency for Research on Cancer (IARC) of the WHO, there is a causal link between alcohol consumption and cancers of the liver, female breast, colorectum, and upper digestive tract. However, data had not been available on the number of cancer cases linked to total alcohol consumption or the proportion of cases caused by alcohol consumption beyond the recommended upper limit.

The authors, led by Madlen Schütze at the German Institute of Human Nutrition in Potsdam-Rehbruecke, argue that a substantial proportion (40% to 98%) of the alcohol attributable cancers occurred in individuals who drank more than the recommended guidelines on upper limits of two standard drinks a day in men and one standard drink a day in women. (In this study, a standard drink is defined as containing 12g alcohol and is equivalent to a 125ml glass of wine or a half pint of beer).

The study calculated that in 2008, current and former alcohol consumption by men was responsible for about 57,600 cases of cancer of the upper digestive tract, colorectum, and liver in Denmark, Greece, Germany, Italy, Spain, and Great Britain. Over half of these cases (33,000) were caused by drinking more than two alcoholic drinks per day.

Alcohol consumption by women in the eight countries caused about 21,500 cases of upper digestive tract, liver, colorectum, and breast cancer, of which over 80% (17,400) was due to consumption of more than one drink of beer, wine, or spirits per day. “Our data show that many cancer cases could have been avoided if alcohol consumption is limited to two alcoholic drinks per day in men and one alcoholic drink per day in women, which are the recommendations of many health organisations”, says Madlen Schütze, first author of the study and epidemiologist at the German Institute of Human Nutrition in Potsdam- Rehbruecke. “And even more cancer cases would be prevented if people reduced their alcohol intake to below recommended guidelines or stopped drinking alcohol at all.”

However, critics of the study accused the authors of downplaying the major finding that the principal link discovered was between heavy drinking and cancer, and of ignoring the alleged protective effect of alcohol in relation to cardiovascular disease. One, Professor Giovanni de Gaetano, Catholic University, Campobasso, Italy, concluded:

“The paper’s conclusion is that only 10% of total cancer in men and 3% in women are attributable to alcohol consumption; however, the proportion of this that is attributable to ‘moderate drinking’ is very much smaller. This is especially the case for the truly ‘alcohol-attributable’ cancers such as upper aerodigestive cancers and liver cancer, where the risk is appreciably increased only for very heavy drinkers and alcoholics. The authors’ conclusion that these data support the efforts to reduce alcohol consumption in order to reduce the incidence of cancer is formally correct. However, as moderate alcohol consumption reduces cardiovascular disease and - what is more relevant - total mortality, their conclusion that one should totally abstain from alcohol is not justified based on current scientific data. Further, the authors surprisingly conclude that ‘alcohol consumption should not be recommended to prevent cardiovascular disease or all-cause mortality.’ They should more correctly say that heavy alcohol consumption should be avoided as it is associated not only with cancer incidence increase but also with increased fatal and non-fatal cardiovascular events and total mortality.”

Cancer Council Position Statement

Key messages and recommendations

• Alcohol use is a cause of cancer. Any level of alcohol consumption increases the risk of developing an alcohol-related cancer; the level of risk increases in line with the level of consumption.

• It is estimated that 5,070 cases of cancer (or 5% of all cancers) are attributable to long-term, chronic use of alcohol each year in Australia.

• There is convincing evidence that alcohol use increases the risk of cancers of the mouth, pharynx, larynx, oesophagus, bowel (in men) and breast (in women), and probable evidence that it increases the risk of bowel cancer (in women) and liver cancer. (Convincing and probable are the highest levels of evidence as determined by the World Cancer Research Fund and American Institute for Cancer Research and denote that the relationship is causal or probably causal in nature).

• Together, smoking and alcohol have a synergistic effect on cancer risk, meaning the combined effects of use are significantly greater than the sum of individual risks.

• Alcohol use may contribute to weight (fat) gain, and greater body fatness is a convincing cause of cancers of the oesophagus, pancreas, bowel, endometrium, kidney and breast (in post-menopausal women).

• Cancer Council recommends that to reduce their risk of cancer, people limit their consumption of alcohol, or better still avoid alcohol altogether.

• For individuals who choose to drink alcohol, Cancer Council recommends that they drink only within the National Health and Medical Research Council (NHMRC) guidelines for alcohol consumption.