Alcohol's tangled relationship with cancer has grown more complex, as a new study has found a link between drinking and melanoma, the most serious form of skin cancer. And while the researchers don't understand why yet, white wine shows the highest risk.
Previous studies have found differing results on alcohol's links to cancer. When the body metabolizes ethanol, some is turned into acetaldehyde, a carcinogen that can impair cells' efforts to repair DNA. Scientists have found connections between heavy alcohol consumption and cancers of the liver, pancreas, colon and rectum. While some research has found that light to moderate drinking can lower the risk of other cancers, several studies have found a link between even light drinking and breast cancer.
The new study, published in the American Association for Cancer Research's journal Cancer, Epidemiology, Biomarkers & Prevention, was authored by Eunyoung Cho, an associate professor of dermatology and epidemiology at Brown University. Cho and her colleagues focused on melanoma, a cancer that begins in the cells that produce melanin, the pigment that gives skin its color. While more rare than carcinoma, it can be far deadlier.
"Cutaneous malignant melanoma is the sixth most common cancer in the U.S.," Cho told Wine Spectator. "There will be an estimated 76,380 new melanoma diagnoses and 10,130 melanoma deaths in the US in 2016."
Cho and her team analyzed data from three larger studies, which had tracked more than 210,000 people in the United States for close to two decades. Participants were questioned about their health and their diet, including alcohol consumption, every four years.
Cho's team excluded participants who reported a personal history of cancer and compensated for lifestyle factors, such as age, smoking history, caffeine intake, physical activity, hair color, mole count or body-mass index, as they looked at the data. They did report two limitations—almost all participants were white, so the study's findings cannot be generalized for other racial or ethnic groups. Also, the study did not account for some potential risk factors for melanoma, such as sun exposure.
Cho and her colleagues found that alcohol intake increased the risk of melanoma by 14 percent per drink per day. Women were generally at higher risk, possibly because men metabolize alcohol more effectively. And when they broke the results down by drink type, white wine was the beverage that showed a clear association with a higher risk—other alcoholic drinks raised the risk, but not at a statistically significant level.
Why white wine? The researchers theorized that because wine has higher levels of pre-existing acetaldehyde than beer or spirits, it poses a higher risk. And while red and white wine have similar levels, the antioxidants in red wine may counterbalance the risk. (Previous studies have found that the antioxidant resveratrol may reduce the risk of melanomas and protect the body from sunburns.)
But Cho cautions that more research is needed to fully understand the link. "I don't have a good explanation. This is something we will explore further in the future," she said. For individuals with other risk factors for melanoma, she suggests that reducing alcohol consumption may be something to consider. But she also notes that modest alcohol consumption has been linked with health benefits, such as a reduced risk of cardiovascular disease, so people must consider multiple factors and talk to their doctors.