A study involving 3,927 men in Greater Montreal found that drinking a beer every day over a long period is associated with an increased risk of aggressive prostate cancer.
Many men suffering from advanced-stage prostate cancer appear to share at least one thing in common: they are now or have been heavy drinkers of beer, according to a study by uro-oncologist Pierre Karakiewicz, a professor of urological surgery at UdeM’s Faculty of Medicine.
In the study, published in Cancer Epidemiology in December 2016, Karakiewicz and his co-authors employ a variable called "drink years" – that is, the average number of beers consumed in a day multiplied by the number of years of consumption.
Using this measurement, beer drinkers risk reaching an advanced stage of prostate cancer if they consume one beer a day for 63 years, two beers a day for 31 years or three beers a day for 21 years, and so on.
The study is based on a sample of 3,927 men living in Greater Montreal, with an average age of 64 years.
Close to 4,000 men interviewed
One of the unique characteristics of this study is that it is population-based, giving added relevance to the association between alcohol intake and the development of prostate cancer, particularly for men with the heaviest alcohol consumption.
Karakiewicz and his colleagues Marie-Elise Parent and Claire Demoury first identified all the cases of men diagnosed with prostate cancer in the Greater Montreal area between 2005 and 2009. A total of 1,933 men with this type of cancer took part in the study, representing 80 per cent of the cases diagnosed in Montreal. Since this was a “case-control” study, another 1,994 men from Montreal who did not have cancer were selected as the control group.
In-person interviews were conducted with each of the participants. They were asked about their lifestyle, diet, physical activity, and alcohol consumption habits, including the quantities and types of alcohol consumed over their lifetime.
Risk of prostate cancer starting at age 50
Overall, the researchers found no significant association between heavy consumption of all types of alcohol and prostate cancer. However, the results were very different in the case of heavy drinkers of beer, said Karakiewicz, who runs the Cancer Prognostics and Health Outcomes Unit at the University of Montreal Health Center (CHUM).
“Men in the upper quartile of beer consumption – over 63 'drink years' or more, that is to say a case of 24 beers every week for over 18 years, for instance, or a case of 12 a week for over 36 years – had a 40% increased risk of advanced prostate cancer compared to the control group," he said.
Men whose beer consumption was slightly above average did not see an increase in their risk of developing prostate cancer. It’s only when the daily quantity of beer consumed reaches a certain threshold that the risk starts to rise. “For example, our model shows that for a man who starts drinking at the age of 18 and drinks more than two beers every day, the risk of a high-grade prostate cancer appears at the age of 65. If he drinks more than three beers a day, the risk emerges at 50 years of age,” Karakiewicz explained.
“At least one out of five participants in the study consumed beer at levels above what is considered safe,” he added. Given that the cumulative consumption of beer over a lifetime appears to be a predictor of disease, he believes that it should be taken into account by physicians and urologists when seeing patients.
The researchers have not yet been able to clearly identify the mechanism responsible for the greater risk of advanced prostate cancer in heavy beer drinkers specifically.
“We know that acetaldehyde, the first metabolite of ethanol, which is released by alcohol, is a carcinogenic that can promote cancer development by different mechanisms, including interference with DNA replication,” said Karakiewicz.
Other hypotheses point to the possibility that high alcohol consumption can cause folate deficiency (vitamin B) or lead to immunosuppression that may facilitate the spread of tumours.
“These mechanisms should apply regardless of the type of alcoholic beverage consumed,” he explained. “But we also observed a 25% lower risk of prostate cancer in consumers of spirits, so further investigation of these mechanisms is clearly needed.”
The overall findings of this study underscore the importance, in his view, of taking into account alcohol consumption, particularly beer intake, when screening patients for prostate cancer.
Note: This text has been revised
This text was revised on Sept. 11, 2018 to correct an erroneous assertion that drinking 63 beers a year can lead to a higher risk of prostate cancer. In fact, the text should have referred to the variable of "drink years" and calculated the risk accordingly. The text was further revised on Sept. 13 to expand a quote by Professor Karakiewicz about what constitutes heavy drinking, in terms of cases of beer per week.