A new study revealing a key possible mechanisms for how alcohol can cause cancer has been published in the journal Nature, attracting significant media attention and expert reactions.
Whilst links between alcohol and at least seven types of cancers has been increasingly highlighted in recent years and was a key factor in the revision of the recommended drinking guidelines in 2016, scientific understanding of the precise mechanisms has been limited.
The study found that in mice, acetaldehyde, produced when the body breaks down alcohol, could permanently damage DNA. The body however has two main defence responses to acetaldehyde, firstly using acetaldehyde dehydrogenases (ALDH) to break down acetaldehyde. Secondly, the body uses cells to repair damage caused to the DNA, but a range of factors can affect how well the body is able to do so. For example, populations in South East Asia have been found to have lower levels of ALDH enzymes or carry faulty versions, according to a Cancer Research UK press release. Where the body is not sufficiently able to respond to acetaldehyde, it can 'break and damage DNA within blood stem cells leading to rearranged chromosomes and permanently altering the DNA sequences within these cells', explained further here.
Cancer Research UK highlight that the results remind us that cancer does not just come down to genes or ‘bad lack’ as lifestyle factors including alcohol use can influence risk, previously suggesting 40% of cancers could be prevented by improving health. In 2016 Cancer Research UK released research suggesting alcohol-related cancers in England could cause around 135,000 deaths over the next 20 years in England. Prof Linda Bauld, an expert on cancer prevention at Cancer Research UK, said “We know that alcohol contributes to over 12,000 cancer cases in the UK each year, so it’s a good idea to think about cutting down on the amount you drink.”
Implications for policy and practice?
Whilst further understanding about the mechanisms by which alcohol may increase cancer risks may have important implications, policy debates will no doubt continue to focus on the recommended drinking guidelines themselves and how they should be communicated. Whilst some health groups have been promoting a 'no safe level' messages given the potential for increased risk from drinking at any level, others have been far more cautious given the still very small absolute increases in cancer risk at low levels of drinking.
As such, communications and policy about alcohol and cancer risks have been subject to controversy, not least the CMO's infamous comments about her contemplating cancer risk with every glass of wine. Last year research by LSHTM hit the headlines following a study reporting that the alcohol industry misrepresents the link between drinking and cancer risks through strategies such as 'denying, distortion and distraction', whilst CRUK and other groups continue to call for measures to increase awareness such as mandatory health warning labels.
The issues therefore seems to return to the central questions over how risk messages can or should be used to best support informed decision making, and who should have roles and responsibilities in doing so. Last year an editorial on risk in addiction science, policy and debate warned against simplifying risk in public health communications, calling for approaches that recognise the complexity of how risk is calculated and how individuals balance risk in their day-to-day lives. While most would likely agree with this in principle, a wide discrepancy exists between what action groups such as a Cancer Research UK wish to see and the position of industry or 'consumer' affiliated groups such as Drinker's Voice. No doubt debates about how cancer and other risks should be communicated will continue through 2018.
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