Alcohol Consumption Associated with Elevated Cancer Risk in Japan

A study published in Cancer suggested that in Japan, alcohol consumption, even in light to moderate levels, appears to be associated with elevated cancer risks.¹

Although the impact of lifetime alcohol consumption varied across each cancer site, the elevated overall cancer risk appeared to be explained by alcohol-related cancer risk across relatively common sites, including the colorectum, stomach, breast, prostate, and esophagus.

“In Japan, the primary cause of death is cancer. Given the current burden of overall cancer incidence, we should further encourage promoting public education about alcohol-related cancer risk,” Masayoshi Zaitsu, MD, PhD, of the University of Tokyo and the Harvard T.H. Chan School of Public Health, said in a press release.²

In this multi-center cohort of 63,232 cancer cases and 63,232 controls, the minimum risk was at 0 drink-years, and the odds ratio (OR) at 10 drink-years was 1.05 (95% CI, 1.01-1.11). This association suggested that a light level of drinking at the 10-drink-year point would increase overall cancer risk by 5%. Participants who drank 2 drinks or fewer per day had elevated odds for overall cancer risk across all duration-of-drinking categories.

For specific cancer sites, most gastrointestinal and upper aerodigestive cancers, as well as breast and prostate cancers showed the same pattern at light to moderate drink-year levels; this was most pronounced for esophageal cancer (OR at 10 drink-years, 1.44; 95% CI, 1.33-1.57). Pancreatic, cervical, renal pelvis and ureter, and bladder cancers, as well as bone and soft-tissue cancers showed a slight potential linear association. No protective association (but a potential linear association) was observed in kidney cancer, whereas light to moderate alcohol consumption was potentially associated with a reduced risk for skin cancer and multiple myeloma.

The patterns were mostly identical regardless of sex, drinking/smoking habits, drinking durations, or occupational classes.

All participants reported their average daily alcohol consumption in standardized alcohol units and duration of drinking. One standardized drink containing 23 grams of ethanol was equivalent to one 180-milliliter cup (6 oz.) of Japanese sake, one 500-milliliter bottle (17 oz.) of beer, one 180-milliliter glass of wine, or one 60-milliliter cup (2 oz.) of whiskey.

“We have demonstrated a comprehensive picture of significant overall cancer risk and risks of various cancers associated with light to moderate levels for the total amount of lifetime alcohol consumption in Japan with a restricted cubic spline method and a clinically useful indicator of drinking intensity,” the researchers wrote.

A common genetic vulnerability to acetaldehyde in the Japanese could explain the observed patterns for upper aerodigestive and gastrointestinal cancers. No protective effects of light to moderate lifetime alcohol consumption for colorectal and kidney cancers were observed. Different pathways such as elevations of circulating sex hormone levels by alcohol use may explain the alcohol-related cancer risk for breast and prostate cancer. Currently, evidence for potential mechanisms that may explain reduced odds for skin cancer and multiple myeloma remains scarce.

Studies suggest that the ethanol, but not the other components of alcoholic beverages, matters primarily for cancer risk, regardless of the types of alcoholic beverages. Moreover, benefits of adequate, nonheavy alcohol drinking have been reported for overall mortality as well as cardiovascular health.

In 2018, the American Society of Clinical Oncology stated that more than 5% of new cancer cases were attributable to alcohol consumption. However, in Western settings, alcohol-related cancer risk has been characterized as a J-shape pattern in instances of colorectal and kidney cancers, suggesting potential protective effects of alcohol.

References:

1. Zaitsu M, Takeuchi T, Kobayashi Y, Kawachi I. Light to Moderate Amount of Lifetime Alcohol Consumption and Risk of Cancer in Japan. Cancer. doi:10.1002/cncr.23590.

2. Even light alcohol consumption linked to higher cancer risk in Japan [news release]. Japan. Published December 9, 2019. newswise.com/articles/even-light-alcohol-consumption-linked-to-higher-cancer-risk-in-japan?sc=sphr&xy=10021790. Accessed December 10, 2019.