(RxWiki News) Does light drinking lead to higher risk for certain cancers? It depends on what factors are being considered. In this case, there are two sides to the story.
A recent study looked at 222 cancer studies and found links between light drinking and head and neck and breast cancers.
After its publication, a team reviewed the study and found major errors. So the debate goes on about what light drinking does to cancer risks.
"Look at all the information with cancer studies."
Vincenzo Bagnardi, PhD, a student in statistics at the University of Milan-Bicocca in Milan, Italy, led an investigation into light drinking as a risk for certain cancers.
Study results found a high risk of neck and breast cancers in light drinkers.
Using statistical analysis, Bagnardi’s research team evaluated 222 studies conducted prior to 2010.
Bagnardi’s team found approximately 92,000 light drinkers and 60,000 non-drinkers, all with cancer, and analyzed the data to determine the risk of light drinking with certain cancers.
Light drinking was defined as one alcoholic drink per day.
Researchers found no link between light drinking and colorectal, liver and larynx cancers.
However, Bagnardi’s team linked light drinking to approximately 5,000 deaths from throat cancer, 24,000 from esophageal and 5,000 from breast cancer in 2004.
Upon publication, a team of reviewers from Boston University School of Medicine evaluated Bagnardi’s study.
Reviewers discovered, while the math was correct, the study design was majorly at fault—rendering Bagnardi’s study untrustworthy.
The reviewers from Boston University critiqued Bagnardi’s study for errors in the methodology.
One of the reviewers said, “Clearly the issue is that the authors are focusing on the few cancers that are increased by alcohol and ignoring all of the improved health outcomes of light drinking.”
“So, while their data are likely to be ‘true,’ their approach ignores, apparently deliberately, the many diseases that are mitigated and reduced by light alcohol consumption, as well as the reduction in total mortality.”
Bagnardi’s study design flaws included, but were not limited to:
• Including ex-drinkers in the non-drinker group, with no way to tell if these ex-drinkers were once heavy drinkers.
• Didn’t account for when ex-drinkers stopped drinking.
• Didn’t account for how long ex-drinkers had been drinkers.
• Didn’t account for how long ago ex-drinkers stopped drinking.
• Didn’t separate light-drinkers from binge-drinkers.
• Didn’t account for smoking, genetics or lifestyle risk factors for cancer.
These variables could skew data analysis as former heavy drinkers could still have an increased risk for cancer.
The more appropriate grouping would have been ‘never drinkers’, to provide the essential ‘no-risk from drinking’ group variable.
Risk for cancer is also different for people who have one drink per day vs. people who binge drink.
Binge drinkers don’t drink every day, but do engage in drinking more than four, for women, or five, for men, alcoholic drinks in one sitting.
Reviewers found that only 46 percent of the studies included in Bagnardi’s analysis could possibly be considered appropriate.
Reviewers concluded, “It is unfortunate that this approach is often accepted by journals in instances showing problems, but not when showing benefits, associated with light drinking.”
This study was published in August in the Annals of Oncology. No financial information was provided. No conflicts of interest were reported.