The alcohol industry would prefer that alcohol did not cause cancer
OPINION: Alcohol Action New Zealand and the Cancer Society ran a joint one-day conference recently at Te Papa to discuss alcohol and cancer.
I was surprised by the lack of response from the alcohol industries in the media.
Their formula of intervening to spread doubt about the credentials of the researchers, and therefore the evidence, can usually be relied upon when we talk openly about the health effects of alcohol. On reflection, I see that an immediate response would have initiated an unwinnable debate over the evidence.
Eventually on July 22, an opinion piece appeared in The Dominion Post from an eminent-sounding individual claiming that the "group of well-intentioned academics" holding the conference were wrong, and drinking alcohol does not cause cancer.
According to Samir Zakhari, "Cancer is not an easy topic" and "attributing cancer to social moderate drinking is simply incorrect and is not supported by the body of scientific literature".
I was not named in this piece, but the research he referred to was clearly mine.
The article contains errors of fact, errors of interpretation, and much tried-and-true industry rhetoric.
In just one example, the author cites Health Promotion Agency research showing how wrong I am.
If he had opened the report, he would have discovered that I wrote it.
He says: "According to New Zealand Health Promotion Agency research, in 2007 an estimated 5.4 per cent per cent of all deaths were associated with alcohol consumption. A fraction of those were from diagnosed cancers associated with long-term alcohol use, often at high levels of consumption."
This is the research that I was discussing in more detail at the conference, conducted with a local research fellow and the lead researchers from the Global Burden of Disease Alcohol Group.
The first sentence of this quote is almost correct; they were actually deaths under 80 years of age.
The second is largely made-up and misleadingly attributed to my project.
The "fraction" of alcohol deaths due to cancers was not the tiny fraction implied, but 30 per cent, and the deaths were not "associated with long-term alcohol use" or "often at high-levels of consumption".
The evidence that alcohol causes cancer is not in doubt.
The biology and the epidemiology (disease occurrence in populations) is highly consistent.
The International Agency for Research on Cancer has accepted the evidence of causality for human cancer of the mouth and oropharynx, larynx, oesophagus and liver since 1988, and for breast, colon and rectum since 2007.
Many studies contributed to classification of alcohol as a Class 1 carcinogen, and many have followed.
A large meta-analysis published this year combined data from 572 studies, which included 486,538 people with cancer, and findings were consistent with IARC.
There is no evidence of a threshold that consumption has to reach to increase risk, so there is no completely safe level of drinking. The risk simply increases with dose.
Meta-analyses provide risk estimates that allow us to quantify alcohol-attributable cancer deaths and morbidity here. Our study attributes about half of the 243 alcohol-related cancer deaths in 2007 to drinkers consuming less than 4 standard drinks per day (approximately half a bottle of wine) on average.
Among women, about a third of alcohol deaths are associated with consumption of less than 20 grams of alcohol per day (2 standard drinks).
A similar picture has been seen in the U.S. When a 2013 meta-analysis looked specifically at whether very light drinking was associated with increased risks of cancer, it found that an average of one drink or less per day still increased risk for cancer of the mouth and pharynx, oesophagus, and breast.
Dr Zakhari chooses to quote from the the Dietary Guidelines for Americans about the beneficial effects of "moderate" drinking on cardiovascular disease and overall mortality.
This evidence is heavily contested.
We would do much better to refer to our own up-to-date evidence-based guidelines on alcohol and health, from the New Zealand Medical Association, the National Heart Foundation, and the Cancer Society.
These documents are available on the organisations' websites, and all include a thoughtful assessment of the international research.
So why would someone go to the trouble of publishing an incoherent and misleading account of such an important topic?
The answer is that the author is an employee of a large alcohol industry lobby group. His job is to cast doubt on the work of scientists and public health professionals who are working on understanding and quantifying the health harms from alcohol and, most of all, working towards evidence-based policy to reduce harm.
Reducing harm means reducing consumption, and so researchers and advocates are routinely targeted. To be effective in this arena the industry needs to employ people who have scientific credentials. This is partly in order to understand the opposition and use the evidence, but also for credibility when they represent their organisation.
Regardless of their background, people who work for alcohol lobby groups do just that.
They learn the patter, they disrespect the professionals who are working for better public health, and they disrespect the communities into which they intrude with their mischief-making.
We don't need advice from Uncle Sam on what to believe.
We need to accept that there is at least 60 years of science that shows that drinking alcohol increases the risk of some types of cancer, including common ones.
We need to understand that reducing the amount we drink is one way we can reduce our own individual chance of getting cancer.
If we reform our alcohol policies in line with the recommendations made by the Law Commission in 2010, consumption go down across the whole population and our individual choice will be easier.
The incidence and burden of cancer in New Zealand will diminish in response to less drinking, so lets talk about that instead.
Professor Jennie Connor, Preventive and Social Medicine at Otago Medical School, Dunedin.
- The Dominion Post