March 25, 2015

expert reaction to World Cancer Research Fund report on alcohol consumption and liver cancer

The World Cancer Research Fund has published a report into diet, nutrition, physical activity, and their association with liver cancer. The report states that there is strong evidence that consumption of more than three alcoholic drinks per day, or having a BMI higher than recommended, can contribute to liver cancer.

Ms. Catherine Collins, Principal Dietitian at St George’s Hospital NHS Trust, said:

“From a UK perspective, it’s interesting that WCRF have defined 3 alcoholic drinks in this report as 45g of alcohol, which equates to just under 6 units (1 unit= 8g) – this is already double the current UK safe drinking recommendation of 2 units daily for women, 3 units daily for men to include some abstinent days.

“Section 3 of the report states that 90-95% of people who develop hepatocellular carcinoma have cirrhosis- this is an important fact as it shows that it is the damaging effect of alcohol on liver which predisposes to cancer – and that cirrhosis represents the ‘defeat in battle’ of the liver’s attempts to neutralise the toxic effects of alcohol.

“In addition to direct toxic effects on liver, in industrialised countries the additional 56kcal load per 8g/10ml alcohol unit will, with any sugar naturally in the drink – add to overall energy intake, which if excessive for body needs will cause weight gain. With a diet providing more calories than the body needs the fate of excess carbohydrates and alcohol consumed will be to increase blood triglycerides- portable fat particles which have the ability to be utilised as an energy source or ultimately deposited as body fat. These triglycerides can be temporarily stored in the liver and pancreas and are a major cause of fatty liver (a precursor to non-alcoholic fatty liver disease, which can progress to cirrhosis) and acute pancreatitis.

“There is a genetic condition where people lack the second liver enzyme necessary to neutralise alcohol effectively, causing a build up of toxic acetaldehyde and accelerating liver cirrhosis. Whilst this is of major concern in the Japanese population, anyone whose party trick is for their face to turn bright red for hours as soon as they take alcohol may have the same enzyme deficiency

“One small caveat is that the report acknowledges that liver cancer is hard to identify until symptoms develop. In advanced liver disease the body accumulates litres of fluid, so weight at diagnosis may not relate to body fatness”

Prof. Naveed Sattar, Professor of Metabolic Medicine, University of Glasgow, said:

“There is clear evidence of a synergistic effect of alcohol intake and obesity on risk for liver disease and cancers – hence it’s clear that if individuals wish to lessen their risk of liver disease, they need to improve diet and lessen weight gain or reduce weight and cut alcohol intake. In addition, the recent evidence that moderate alcohol protects against heart disease has also been challenged so that it now appears that any amount of alcohol is potentially bad for individuals for a number of chronic diseases. Presently, it’s simply too easy to buy alcohol at cheap prices and many suffer by becoming addicted to alcohol. The good news is there appears to be less binge drinking in the United Kingdom so that some messages are perhaps taking hold.”

Prof. Sir David Spiegelhalter, Winton Professor of the Public Understanding of Risk, University of Cambridge, said:

“This story is being promoted in a misleadingly sensational way. The increase in risk of liver cancer per 10g alcohol consumed is only about 4%- so while it ‘can cause’ cancer, that level of alcohol is extremely unlikely to. And the report says that this risk increase only starts at levels above about 45g of alcohol per day, but this is 5.5 units, which is already a lot of alcohol (about equivalent to 500mls of 11% wine).

“Following on from this, increasing alcohol consumption from 500mls (two thirds of a bottle of wine per day) to a whole bottle day is an extra 22g of alcohol and subsequently increases risk of liver cancer by 10%.

“Liver cancer is rare: about 1 in 100 men and 1 in 200 women get it in their lifetime. So if you already drink a lot, and then drink even more, your risk goes up a small amount.”

Prof. Paul Pharoah, Professor of Cancer Epidemiology, University of Cambridge, said:

“Alcohol consumption affects a wide range of health outcomes and it makes little sense to have a recommendation about drinking based on a single association, particularly primary liver cancer as discussed in this report.

“Primary liver cancer is quite rare in European populations, but much commoner in parts of the world where chronic hepatitis due to viral infection is common. In the UK, the lifetime risk of primary liver cancer is about 1: 100 for men and 1:200 for women.

“The authors of this report have reviewed the scientific literature reporting studies that have evaluated the association between alcohol consumption and primary liver cancer. It is well established that individuals with liver cirrhosis are at a substantially increased risk of developing primary liver cancer and that high alcohol intake (four or more drinks per day) is associated with both cirrhosis and primary liver cancer. What is less clear is whether moderate alcohol consumption is also associated with an increased risk.

“The authors report that there is a clear increase in risk of primary liver cancer for individual who drink three or more alcoholic drinks (standard units) each day. While the authors have listed the studies they reviewed, they have not presented the details of the evidence on which this is based. I do not think the published data are sufficiently robust to conclude that three drinks a day specifically is associated with an increased risk of primary liver cancer for the following reasons.

“Many of the studies cited were carried out in population in the far east where the prevalence of chronic hepatitis infections – also associated with an increased risk of primary liver cancer – is higher than in Europe. It is possible that moderate alcohol consumption is only a risk factor for those with chronic hepatitis.

“In two of the larger European studies cited (Persson et al and Trichopoulos et al) there was no increase in risk of primary liver cancer  for an individual drinking 1-3 alcoholic drinks a day. Whereas both studies reported clear evidence that 4 or more drinks is associated with an increased risk of primary liver cancer (a little less than two-fold relative).

“Thus the very specific recommendation is not really justified by the evidence. If every daily drink (10g alcohol per day) were associated with a 4 per cent relative increase in risk (relative risk 1.04 as stated in this report), three drinks a day would be associated with an absolute increase in risk from 10 in a thousand to 12 in a thousand for men and 5 in a thousand to 5.6 in a thousand for women. In other words a very small increase.

“Even though the data specifically related to primary liver cancer do not support the recommendation to limit alcohol intake to one drink a day for women and two a day for men, there are plenty of other reasons to support the recommendations.”

‘Continuous Update Project Report: Diet, nutrition, physical activity and liver cancer’ published by the World Cancer Research Fund on Wednesday 25th March. 

Declared interests

None declared