Underreporting of alcoholic beverages consumption affects the relation of alcohol to the risk of cancer

The apparent risk of cancer among light–moderate drinkers may occur primarily among those who underreport their actual intake of alcoholic beverages.

There is strong evidence that heavy consumption of alcoholic beverages is related to increased risk of several cancers. But the relationship of light-to-moderate drinking is less clear. This subject has been thrust into public health consciousness by meta-analyses and reviews leading to statements that the alcohol-cancer association is continuous at all drinking levels and that there is no safe amount of ethanol intake from viewpoint of cancer risk.

Epidemiologists are often faced with reported adverse health effects of alcoholic beverages among subjects reporting very low levels of consumption, levels that physiologically should not cause diseases such as cancer.  It is often assumed that at least some of the subjects reporting low levels of intake may be underreporting their actual intake (this means that some heavy drinkers misstate the amount they drink intentionally or unintentionally), but until now it has been difficult to assess this.

In the present study, computer-based data of more than 120,000 subjects (of the Kaiser Permanente Study) on their medical conditions and diseases related to alcohol use, collected over many years, were used to identify subjects reporting “light-to-moderate” alcohol intake who were likely, or unlikely, to be under-reporting their intake at a baseline examination. 18.4% of subjects were suspected of being under-reporters while 46.5% had adequate data that suggested that they were not under-reporting (the remaining 35.1% of subjects had inadequate data stored in the computer to be classified).

During an average follow-up period of 18 years, 14,880 participants developed cancer.  There were 23,363 subjects who reported that they were light (up to 1 drink/day) or moderate (1 to 2 drinks/day) drinkers.  In all comparisons, subjects suspected of being under-reporters with regards to their intake of alcoholic beverages had a higher risk of cancer than those not categorized as being under-reporters. For example, among participants reporting 1 to 2 drinks/day, compared to non-drinkers, the risk ratio of any type of cancer among those considered to not be under-reporters was 0.98; in other words, no effect on cancer risk from alcohol.  For those categorized under-reporters, however, the relative risk of any cancer was 1.33.  Similar results were seen for alcohol-related cancers as for any other cancer.  Also, the risk of breast cancer among women was less than one-half as high among moderate drinkers who were unlikely to be under-reporters as among those considered likely to be under-reporting their drinking.

Based on the present study, an increase in the risk of cancer among light-to-moderate drinkers may occur primarily among those who underreport their alcohol intake.

Klatsky AL, Udaltsova N, Li Y, Baer D, Tran HN, Friedman GD.  Moderate alcohol intake and cancer: the role of underreporting.  Cancer Causes Control 2014; on-line publication; DOI 10.1007/s10552-014-0372-8 2014.

For more information about this article, read the scientific abstract here.