Light to moderate lifetime alcohol use raises cancer risk

By Dr. Ananya Mandal, MDDec 11 2019

There have been conflicting reports on health benefits and harm caused by drinking alcohol. A new study from Japanese researchers has proven that taking one drink a day for a decade or two drinks for five years can raise the risk of getting cancers by 5 percent. The study titled “Light to moderate amount of lifetime alcohol consumption and risk of cancer in Japan,” was published in the latest issue of the journal Cancer.

Image Credit: Viktoriia Hnatiuk / Shutterstock

The correlation between cancers and alcohol consumption has been a topic for debate over the past few years. The team wrote, “In Western settings, alcohol‐related cancer risk has been characterized as a J‐shape pattern in some instances (colorectal and kidney cancers), and this suggests potential protective effects of alcohol. However, in 2018, the American Society of Clinical Oncology stated that more than 5% of new cancer cases were attributable to alcohol consumption.”

For this study the team of researchers used data from hospital records between 2005 and 2016 in Japan for 63,232 cancer patients and 63,232 non-cancer patients. They adjusted the analysis for other factors such as age of the individual, smoking status, other ailments, occupational hazards and gender. They calculated the, “total amount of lifetime alcohol consumption (drink‐years) was recalled for each patient by multiplication of the daily amount of standardized alcohol use (drinks per day) and the duration of drinking (years).

Final results showed that taking a single drink a day for 10 years or two drinks a day for five years could raise the risk of getting breast, prostate or gastrointestinal tract cancers by 5 percent. They wrote, “One standardized drink containing 23 g of ethanol was equivalent to one 180‐mL cup (6 ounces) of Japanese sake, one 500‐mL bottle (17 ounces) of beer, one 180‐mL glass (6 ounces) of wine, or one 60‐mL cup (2 ounces) of whiskey. References or controls to the patients were individuals who were abstainers for life. The team wrote, “Lifetime abstainers of drinking were defined as those who responded that they had never consumed alcohol.”

Speaking on the prevalence of drinking, they authors of the study wrote, “Overall, the cases tended to drink more than the controls: the prevalence of ever drinkers among the cases and controls was 59.9% and 56.0%, respectively (P < .001), and the mean drink‐years for the cases and controls were 38.1 and 33.7, respectively (P < .001).”

Regarding the results the team wrote, “Those who drank 2 drinks or fewer per day had elevated odds for overall cancer risk across all duration‐of‐drinking categories. The same patterns were observed at light to moderate levels of drinking for most gastrointestinal/aerodigestive cancers as well as breast and prostate cancers. Analyses stratified by sex, different drinking/smoking behaviors, and occupational class mostly showed the same patterns for overall cancer incidence associated with light to moderate levels of drinking.”

The team explains that hormones could play a role in this association between the cancers and the alcohol consumption. The metabolites formed from the breakdown of alcohol seem to affect the body’s capability in handling other toxic chemicals and nutrients and this may raise the risk of cancers say researchers. The team explained in their paper, “Light to moderate levels of alcohol consumption may affect cancer risk through multiple pathways. For example, alcohol use increases circulating sex hormone levels, and this contributes to excess breast cancer risk. In addition, acetaldehyde, a metabolite of ethanol classified as a group 1 carcinogen by the International Agency for Research on Cancer, stimulates cell proliferation and induces DNA damage.”

“Given the current burden of overall cancer incidence, we should further encourage promoting public education about alcohol-related cancer risk,” Zaitsu said in a statement.

According to the lead author of the study Masayoshi Zaitsu, of The University of Tokyo and the Harvard T.H. Chan School of Public Health, this study is important for the Japanese population. The team wrote, “We observed modest alcohol‐related cancer risk in the most common types (colorectal, stomach, breast, prostate, and liver cancers) even at light to moderate levels of lifetime alcohol consumption in Japan. Thus, given the current burden of overall cancer incidence, we should further encourage promoting public education about alcohol‐related cancer risk.”

Authors wrote in conclusion, “In summary, we have documented various cancer risks associated with even light to moderate levels for the total amount of lifetime alcohol consumption in Japan, with the minimum risk at zero consumption. The current national cancer control strategy needs to strengthen the emphasis on moderating drinking behavior in the Japanese population to reduce the burden of cancer incidence.”

This study received funding from the Ministry of Health, Labour, and Welfare and the Japan Society for the Promotion of Science.