Heavy Drinking Could Be Linked to Lung Cancer, Scientists Believe

Scientists have identified six genes which they believe are linked to drinking alcohol in excess. By studying the genes of tens of thousands people, the team also found heavy drinking could raise the risk of developing lung cancer.

The study involved 125,249 people from the U.K. who drank and were taking part in an existing study. The scientists carried out what is known as a genome-wide association study. This is where researchers look for small variations in a person's DNA for what are known as single nucleotide polymorphisms (SNPs), study co-author Andrew Thompson, a senior research Associate at the University of Liverpool, told Newsweek.

"Each person carries many millions of SNPs, but if a particular SNP occurs more frequently in people with a particular condition/behaviour than in people without the condition/behaviour, it can suggest the underlying reason for the difference," he said. The results were then replicated in 47,967 participants of a U.S.-based study. Half a dozen genes were found to be linked to the behaviour, which could tweak how people metabolise sugar, the authors believe.

Next, the team used worm models to test what happens when the genes were removed. All the tests showed marked changes in the worms' response to consuming alcohol, said Thompson.

This "suggests that these genes have a true impact on response to alcohol," he said. "When exploring the biological implications of the genes we found evidence to suggest several common pathways associated with different types of compulsive behaviour and addiction, not just alcohol consumption."

Heavy drinking was defined as at least 35 units per week for women, and at least 50 units per week for men, according to U.K. measures. One unit, for instance, amounts to a single 25ml (0.9 oz) shot of spirits at 40 percent ABV.

The researchers were surprised to find a link between alcohol and lung cancer risk, he said. Lung cancer has been linked to alcohol consumption in the past, explained Thompson. But experts have struggled to uncover what is underlying the association as people who drink often also smoke: another risk factor for the disease.

By examining the genetics, the study could provide clues of "a causal relationship" in the sample they used, when stratified by smoking status, Thompson said. "Alcohol is a known carcinogen, and is implicated in cancers of the liver, colon, rectum, head and neck, and breast, for example; while evidence for lung cancer is variable," he said.

Drinking alcohol has been previously linked to over 60 diseases, and a person's genetics are thought to play a role in drinking too much. However, it is unclear which parts of the DNA are at play, the authors explained in the paper published in the journal Science Advances. The team hoped pinpointing the genes which contribute heavy drinking could help with creating treatments for dependence, Thompson said.

However, Thompson acknowledged the study was limited because the participants might not have given accurate estimates about how much they drank, and the results might not relate to other populations as the respondents were all of white British ancestry.

The team is now working on samples with patients with other additions to see whether their genetic make-up is similar to heavy drinkers. "This is to explore the hypothesis that genes identified in this work are involved in common pathways associated with different types of compulsive behaviour and addiction," said Thompson.