April 3, 2019 -- Drinking a bottle of wine each week is the same as smoking five to 10 cigarettes a week when it comes to raising the risk of getting cancer, according to a new study that’s gotten widespread mainstream news coverage.
The United Kingdom study was both lambasted and praised by experts approached by Medscape Medical News.
Among men, drinking a bottle of wine each week boosted the absolute lifetime risk of cancer equal to smoking five cigarettes.
The findings were published online March 28 in BMC Public Health. While many published reports and research have looked at the cancer risks of both cigarettes and alcohol, this is the first paper to compare them head-to-head. "We simply performed a calculation based on data from previous large … studies," says lead author Theresa Hydes, PhD, a hepatology clinical fellow at the University Hospital Southampton, England. She says the cigarettes equivalent was used primarily to help raise public awareness of the cancer risk of alcohol.
"The public associates alcohol with liver disease but are generally not aware that it is the fifth leading cause of cancer and, of course, drinking rates are continuing to increase in many countries," Hydes said.
Two experts not involved in the study had different opinions of it.
Ruth Etzioni, PhD, a biostatistician at Fred Hutchinson Cancer Research Center in Seattle, was not convinced that comparing cigarettes and alcohol is helpful.
The title of the paper includes the phrase "How many cigarettes are in a bottle of wine?" According to Etzioni, this shows it was "obviously written to grab attention." Adding, "I would recommend giving it as little attention as possible."
"The cancers induced by smoking, which are very clear, are not the same as the cancers supposedly affected by alcohol -- which are a lot less clear," Etzioni says. "Making this comparison is not helpful and is guaranteed to cause alarm. There is a lot more uncertainty about the risk induced by alcohol consumption than about cigarette smoking."
The study is a disservice to health-conscious people, suggested Etzioni. "This is the kind of work that makes people trying to take decent care of their health tear their hair out."
But another expert says the paper has merit.
"Public health professionals and possibly the public have often speculated about alcohol risks compared to smoking, and this excellent, clear paper provides this information," said Mark Petticrew, PhD, professor of public health evaluation in the faculty of Public Health and Policy at London School of Hygiene and Tropical Medicine, England. "For that reason, it is an unusual and important paper."
He says the authors are not "scaremongering," and they say so. "The paper starts by saying 'we must first be absolutely clear that this study is not saying that drinking alcohol in moderation is in any way equivalent to smoking,' " says Petticrew. "The analysis also looked at cancer in isolation, and alcohol causes other health problems which need to be considered."
One Bottle of Wine Ups the Risk
In their study, Hydes and colleagues estimated the higher chance of getting cancer related to moderate consumption of alcohol and compared it to the higher risk of getting cancer from smoking.
Their results showed that among nonsmoking men, the increase in the lifetime risk of cancer from drinking one bottle of wine per week was 1.0%, while for nonsmoking women, the risk was about 50% higher, at 1.4%.
In men, the higher cancer risk was primarily from gastrointestinal cancers (for example, oropharynx, esophageal, colorectal, liver); in women, breast cancer accounted for 55% of additional cases. The authors emphasized that this finding was important because smoking is also an important cause of GI tract cancers but not breast cancer. So, if 1,000 men and 1,000 women each consumed one bottle of wine per week, an estimated 10 men and 14 women would get cancer as a result.
Not surprisingly, as the amount of alcohol one drinks increased, so did the lifetime risk of alcohol-related cancers. Drinking three bottles of wine per week, or about half a bottle per day, brought a cancer risk increase of 1.9% in men and 3.6% in women, or 19 in 1,000 men and 36 in 1,000 women. This is the same risk from smoking about eight cigarettes per week for men and 23 cigarettes per week for women.
"We are clear that there are no health benefits from drinking," says Hydes. "While these studies are often bought up by the alcohol industry -- overall their findings have now been discredited, often due to the fact that the teetotalers in these studies have abstained due to health reasons and therefore skewed the data. There is now robust evidence that low levels of alcohol intake do not provide any protective health benefits."
She added that the World Health Organization's International Agency for Research on Cancer, the World Cancer Research Fund, and the American Institute for Cancer Research have all said that no level of alcohol consumption is completely safe, which led the UK to change its drinking guidelines in 2016 to say no level of alcohol consumption is completely safe.
Alcohol and the Heart
Petticrew also pointed out that while some studies have found that alcohol may help prevent heart disease, it is unclear, and there may be other explanations for the relationship. "Even if such a protective effect is real -- which is disputed -- it only relates to heart disease, and there are about 200 other conditions which alcohol increases the risk for, including cancer."
Importantly, at low levels of drinking, the risk of cancer is low, Petticrew explained. "Also, in terms of alcohol and heart disease -- if there is a protective effect, it occurs at very low levels."
In terms of communicating this information with the public, the study does raise other questions. "It is important to know how the public would respond to messaging, which describes alcohol risk in terms of cigarettes smoked," he said. "We don't know enough about this. Does the public think that the small increased risk is 'worth it'? Will they reject such messages? This would be an important study to carry out."
The study authors emphasized that while their data represent a realistic comparison, "it must be understood that the risks described are population-level risks, such as that the cancer-causing effect of 10 units of alcohol a week or 10 cigarettes a week will vary on an individual level due to other lifestyle issues, genetics, etc."
Lead author Hydes also pointed out that although they went to great lengths to correct for the combined effect of both drinking and smoking, "this will still be an issue. If you drink and smoke, the cancer risks multiply."
While the health risks of smoking are well established and widely understood by the public, the situation is different with alcohol, especially as it relates to cancer. Even though studies have established alcohol drinking as something that raises your risk of having multiple cancers, awareness in the general public is low. In a 2017 poll by the American Society for Clinical Oncology, for example, 70% of Americans did not recognize alcohol as a cancer risk factor.