Researchers found women who drank up to one alcoholic beverage daily were at greater risk of certain cancers - particularly breast cancer - regardless of smoking history.
Previous studies have associated heavy drinking with greater risk of certain cancers, including breast, colon, liver and mouth cancers.
But according to Prof. Edward Giovannucci and colleagues, from the Harvard T.H. Chan School of Public Health in Boston, MA, there is limited evidence on how light to moderate drinking impacts cancer risk.
What is more, the researchers note there has been little research on how alcohol consumption affects cancer risk independent of smoking. Smoking is a well-established risk factor for many alcohol-related cancers, and because drinkers are more likely to smoke, the authors say smoking may have been a confounding factor in previous studies linking alcohol consumption with cancer risk.
As such, Prof. Giovannucci and colleagues set out to assess the association between light to moderate drinking and cancer, also looking at how such alcohol consumption impacts cancer risk independent of tobacco use.
The team analyzed data from two large US studies involving 88,084 women and 47,881 men, whose health was monitored for up to 30 years.
The alcohol consumption of participants was determined via a dietary intake questionnaire completed every 4 years.
Light to moderate drinking was defined as up to one standard drink, or 15 g or alcohol, a day for women and up to two standard drinks daily, or 30 g of alcohol, for men. One standard drink is the equivalent to a 118 ml glass of wine or a 355 ml bottle of beer.
As well as assessing participants' overall cancer risk, the researchers assessed their risk of alcohol-related cancers, including colon, rectal, liver, breast, oral cavity, pharynx and esophagus cancers.
People with family history of cancer 'should consider abstaining from alcohol'
Over the 30-year follow-up period, 19,269 cancers were diagnosed in women and 7,571 cancers were diagnosed in men.
- In 2013, around 56.4% of American adults aged 18 and older reported consuming alcohol in the past month
- Alcohol contributes to more than 200 diseases and injury-related health conditions
- Each year, around 88,000 people in the US die from alcohol-related causes.
Men and women who engaged in light to moderate drinking were found to be at a small but "non-significant" increased total cancer risk, regardless of their smoking history.
However, the researchers found that women who engaged in light to moderate drinking were at greater risk of alcohol-related cancers, particularly breast cancer. This result rang true for women with and without a history of smoking.
Among men, light to moderate drinking was only linked to increased risk of alcohol-related cancers in those who had a history of smoking.
In an editorial linked to the study, Dr. Jürgen Rehm, of the Centre for Addiction and Mental Health in Toronto, Canada, says the findings from Prof. Giovannucci and colleagues provide a greater understanding of how even light to moderate drinking can influence cancer risk.
While more research is needed to further assess the link between smoking and alcohol consumption on cancer risk, he believes the current findings suggest women should consume no more than one alcoholic beverage daily and men should drink no more than two.
Dr. Rehm adds:
"[...] People with a family history of cancer, especially women with a family history of breast cancer, should consider reducing their alcohol intake to below recommended limits, or even abstaining altogether, given the now well-established link between moderate drinking and alcohol-related cancers."
Last month, Medical News Today reported on a study that found individuals aged 50 and older who are healthy, active, sociable and wealthy may be at increased risk of harmful drinking.