V_ctoria | Shutterstock
Dr Amtul Razzaq Carmichael, UK, and Aizaz Khan, Canada
Alcohol use is a common feature of both social and professional interactions in many countries. Wine is served at professional dinners, social events often centre around alcohol consumption, and alcohol use in general is considered to be a normal and natural part of life, save for those who suffer from alcoholism.
But while the harms associated with high and frequent alcohol consumption have been well-understood, recently emerging evidence demonstrates that even light-to-moderate alcohol consumption is associated with physical, psychological and social harm to individuals and society.[i] In 2010, members of the Independent Scientific Committee on Drugs applied ‘multicriteria decision analysis (MCDA) modelling to a range of drug harms in the UK’ and subsequently published the results of the analysis in The Lancet. Using 16 criteria, they calculated a comprehensive “harm-score” which took into consideration harm caused by drug-specific mortality, drug-related mortality, damage and mental impairment, dependence, loss of tangibles (such as income, housing, job), loss of relationships, injury, crime, environmental damage, family adversities, international damage, economic cost and cost to the community. Using these parameters, alcohol with an overall score of 72 (out of 100), was judged to be the most harmful substance followed by heroin at 55, then crack cocaine with a score of 54. Authors of the report concluded that aggressively targeting harm caused by alcohol is a valid and necessary public health strategy.
Though the harms of alcohol are generally known, one particularly under-appreciated aspect is in its relationship to cancer. For the purpose of this article therefore, we will focus on the effects of alcohol consumption and cancer.
Does Alcohol Lead to the Development of Cancer?
Robust epidemiological and scientific evidence has recognised that alcohol is a carcinogenic agent, with even low and moderate doses of alcohol contributing to the development of cancers of oropharynx, larynx, oesophagus, liver, breast, and colon.[ii] In 2012, almost 6% of all cancer-related deaths and 5.5% of all cancer occurrences were attributable to alcohol.[iii]
Alcohol is carcinogenic even in small doses and the risk of developing cancer continues to increase with increasing doses of alcohol consumption. Epidemiological evidence supports that daily drinking, even at low levels, is harmful to one’s health and any drinking at all contributes to cancer risk.[iv] Even moderate alcohol intake is associated with almost a doubling in the risk of developing cancers of the oral cavity and pharynx; the risk in heavy drinkers is increased more than five-fold.[v] The World Cancer Research Fund/AICR recommend that, ‘…for cancer prevention, it’s best not to drink alcohol.’ And: ‘If alcoholic drinks are consumed, limit consumption to two drinks a day for men and one drink a day for women.’[vi] Acknowledging that alcohol intake is a modifiable risk factor for the development of various cancers, the Cancer Prevention Committee of the American Society of Clinical Oncology (ASCO), has suggested a proactive stance by the Society to minimize excessive exposure to alcohol.
How Does Alcohol Lead to the Development of Cancer?
The exact mechanism by which alcohol leads to the development of cancer is not fully understood. Alcohol can seep through virtually all tissues in the body, leading to alteration in essentially all systems of the body.[vii]
DNA is the building block of the human body – and DNA damage is a feature of cancer development. Alcohol use damages the tissue through several mechanisms, including oxidative stress (an imbalance between important compounds in the body, leading to tissue damage), inflammation, and formation of harmful compounds such as acetaldehyde generation and adduct formation. These lead to a decrease in protective barrier functions, impairment of tissue building, an increase in the breakdown of tissues, activation of cell turnover and injury to mitochondria (the energy-producing subunit of the human cell).[viii] Several factors contribute to alcohol-induced cancer development (i.e. carcinogenesis), principal among them being the effect of acetaldehyde, the first and primary breakdown product of alcohol, along with ‘oxidative stress’. However, there are also other suggested mechanisms that lead to alcohol-induced cancer development.[ix]
Does Alcohol Impact Cancer Treatment?
There is evidence to suggest that high alcohol consumption and alcohol abuse are known to be associated with higher risk of death in those undergoing cancer treatments.[x] Alcohol abuse and high alcohol intake is known to increase the length of stay in hospital because of slow recovery, surgical complications, and higher utilisation of healthcare resources.[xi],[xii],[xiii],[xiv],[xv] Cancer patients who abuse alcohol have increased treatment-related problems because of alcohol-related damage to the body such as deficiency of essential nutrients, suppression of the immune system and diseases of the cardiovascular system.[xvi] [xvii] [xviii]
Cancer survivors who consumed the highest amounts of alcohol have an 8% increased risk of death and more than one in six (17%) r