July 19, 2011
Are Drinking Guidelines Adequate Regarding The Risk Of Cancer?
A group of French scientists (from the Unit of Research on Nutritional Epidemiology, French National Institute for Agricultural Research, Bobigny, France; the French Institute for Prevention and Health Education, St. Denis, France; and the French National Cancer Institute) have published a paper in the Canadian Medical Association Journal (CMAJ) on guidelines for drinking and the relation of alcohol to cancer. They conclude that:
* Guidelines for sensible drinking are based on the short-term effects of consuming alcohol, such as social and psychological problems or admissions to hospital, and disregard the dose"“response relationship between alcohol consumption and cancer risk.
* The current guidelines for sensible drinking for the general population are not adequate for the prevention of cancer.
* Revised guidelines that are based on complete and up-to-date scientific evidence are needed.
It could be argued that The current guidelines for sensible drinking for the general population are not adequate for the prevention of cancer" -- has some merit, if one is discussing heavy drinking. With the exception of breast cancer (and possibly for colon cancer), an increase in cancer risk is associated almost exclusively with heavy drinking (especially alcoholism). This is the primary factor associated with upper aero-digestive cancers, liver cancer, and other "alcohol-related cancers." These are not common outcomes associated with moderate drinking. More importantly, the authors ignore the consistent data from developed countries around the world showing that moderate drinkers are at lower risk of all-cause mortality than non drinkers. Even taking into account an increase in risk for certain types of cancer from alcohol consumption, the authors do not acknowledge that total mortality is higher among abstainers (including lifetime abstainers) than among moderate drinkers.
Many diseases such as cancer affect older people much more than younger. The cardiovascular protection and other possible benefits of low, regular doses of alcohol (less dementia, late onset diabetes etc) are most likely to be visible in older age groups, a time when much research suggests alcohol's positive effects outweigh its negative effects.
Threshold effects: The paper quotes the 2007 review from World Cancer Research Fund/American Institute for Cancer Research cited in the conclusion: "No threshold for risk-free consumption was identified." is misquoted as, thresholds were identified in that document (and in many others), such as an increased risk of colorectal cancer being apparent above a threshold of 30 g/day of ethanol for both sexes, and cirrhosis is an essential precursor of liver cancer caused by alcohol.
Importance of smoking and diet on the association of alcohol with cancer: The paper fails to point out the importance of associated smoking in the risk of upper aero-digestive cancers; in the absence of tobacco smoking there seems to be little or no effect of moderate alcohol consumption on the risk of such cancers. For example, in the Million Women Study, increasing alcohol intake was strongly associated with an increased risk of cancers of the upper aerodigestive tract among current smokers, but was not associated with an increased risk in never smokers or past smokers.
Reasons why people consume alcohol: The authors of the report seem to believe that including categories for sensible or low-risk drinking in guidelines leads people to start drinking alcohol. Humans have consumed various types of alcoholic beverages since long before recorded history. The reasons why some people consume such beverages and others do not are strongly related to cultural norms. It is unlikely that a particular set of guidelines for a country plays a major role in the initiation of consumption, although it may be of some help in reducing consumption in individuals who drink excessively.
Scientific data over many decades have shown that excessive or irresponsible alcohol use has severe adverse health effects, including an increase in the risk of certain cancers. On the other hand, moderate drinking is associated with lower risk of cardiovascular disease and many other diseases of ageing and with all-cause mortality. A very large number of experimental studies, including results from human trials, have described biological mechanisms for the protective effects of the moderate consumption of alcoholic beverages against such diseases. A number of comprehensive meta-analyses provide much more accurate, up to date, and scientifically balanced views than does the current paper; such documents may be better sources of data upon which guidelines to the public regarding alcohol consumption should be based.
Finally, International Scientific Forum on Alcohol Research (ISFAR) reviewers are not aware of guidelines that suggest that non-drinkers should begin to drink. Further, guidelines state clearly that any sensible drinking limits do not apply to minors, pregnant women, etc. The consensus of ISFAR members is that decisions regarding drinking habits should be done by individuals in consultation with their physicians. One of the most respected senior physician/cardiologists in the field and ISFAR member, Dr. Arthur Klatsky of California, has provided some key recommendations regarding giving advice on alcohol use to individual patients: "Such advice depends on the individual's age, sex, past alcohol use experience, cardiovascular risk, and other factors." Klatsky added, "While some patients may rationalize their heavy drinking because of its purported health effects, I have yet to find someone who had developed alcohol abuse because of messages about the health effects of moderate drinking'.
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