A history of moderation may improve your chances of surviving colorectal cancer

You probably know that alcohol is one of the nine points of a Mediterranean-style diet. Research has shown that those who consume a moderate amount of alcohol, mostly with meals, are less likely to develop diabetes or heart disease than those who do not consume alcohol, while those whose intake is excessive (4 or more drinks per day for women, or 4 1/2 drinks per day for men) are almost twice as likely to develop diabetes. One theory is that it's the antioxidants in wine that confer the protective effects, although we also know that all types of alcohol (wine, beer, or liquor) help reduce the markers of inflammation that are associated with chronic conditions like diabetes, heart disease, and cancer.

That said, the risk of developing gastro-esophageal (esophagus and stomach) cancers is slightly (just 1%) higher among those who drink. A new study in the American Journal of Clinical Nutrition looks at alcohol use and survival in those diagnosed with colorectal cancers (2016;103:1497-506).

The authors used information gathered through an ongoing case-control study in Germany. (A case-control study compares those who have been diagnosed with a disease with those who do not have the disease in an effort to discover possible contributing causes of the disease.) Over 3,000 men and women who had recently been diagnosed for the first time with colorectal cancer (CRC) responded to demographic, medical, and lifestyle history questionnaires that included estimates of the participant's alcohol intake, both in the past (at ages 20, 30, 40, etc.) and within the year just prior to their diagnosis.

For the following 5 years, on average, the authors were updated by the patients' physicians regarding treatment and recurrence, and causes of death for those patients who died during those five years were collected from their local public health departments. The participants' alcohol intake was defined as "abstainers" (those who did not drink at all), "light drinkers" (up to 1 drink per day for women and up to 2 for men), "moderate drinkers" (between 1 and 2 drinks per day for women, 2-4 for men), and "heavy drinkers" (more than 2 drinks per day for women, more than 4 for men).

The authors found that compared to light drinkers, those who abstained from drinking any alcohol over their whole lives had lower rates of overall five-year survival (meaning they did not die of any cause) and much lower rates of CRC-specific survival (dying from colorectal cancer specifically). On the other hand, compared to light drinkers, heavy drinkers also had lower rates of overall survival and were far less likely to survive disease-free for the five years of follow-up. This tendency for abstainers and heavier drinkers to fare less well than those who were light or moderate drinkers held true across the various outcomes the authors considered, from risk of recurrence to risk of death from CRC.

What this means for you

Case-control studies are always retrospective, and in this case asks the participants to estimate their past intake of alcohol. Given that all of the participants had been diagnosed with colorectal cancer, it's possible that their recall was less than accurate: they may have unconsciously under-reported their alcohol intake due to the stigma associated with regular drinking. This study does, however, mirror the other positive effects of moderate alcohol intake and should be considered all the more reason to keep your drinking moderate (and with meals). As always, if you abstain from drinking this study should not be taken as requiring you to start.

First posted: June 29, 2016