Alcohol Consumption and Risk of Colorectal Cancer

Reference

Crockett SD, Long MD, Dellon ES, Martin CF, Galanko JA, Sandler RS. Inverse relationship between moderate alcohol intake and rectal cancer: analysis of the North Carolina Colon Cancer Study. Dis Colon Rectum. 2011;54(7):887-894.

Design

Population-based case-control.

Participants

The study included 1,033 patients diagnosed with colorectal cancer and 1,011 controls from 33 counties in the central and eastern part of North Carolina. African-Americans were oversampled to be proportionate to their incidence of colorectal cancer.

Intervention

Nurses interviewed participants for demographics and dietary intake using a validated questionnaire. Data were adjusted for age, sex, race, smoking status, obesity, education, red meat intake, use of nonsteroidal anti-inflammatory medications, and family history of colorectal cancer.

Outcome Measures

Odds ratios for the relationship between alcohol consumption and distal colorectal cancer incidence were calculated using logistic regression.

Key Findings

Moderate alcohol intake (especially wine) was associated with lower rectal cancer incidence. Moderate drinkers (≤14 g/day or ≤1 drink a day) were 44% less likely to develop rectal cancer as compared to nondrinkers (OR=0.66; 95% CI: 0.53–0.82). Drinkers of any amount had a 27% lower risk of rectal cancer compared to nondrinkers (OR=0.73; 95% CI: 0.60–0.90). In addition to the decrease in rectal cancer risk, moderate beer drinkers had a 24% decreased risk of distal colorectal cancer (OR=0.76; 95% CI: 0.60–0.96), while moderate wine drinkers had a 31% risk decrease (OR=0.69; 95% CI: 0.56–0.86).

Study Limitations

Strengths of the Crockett study include large sample size and a focused research question in the study design. These factors increase statistical power and decrease likelihood of type I error. The proportional oversampling of African Americans also supports the generalizability of the study. Limitations of the Crockett paper and other retrospective studies include possible recall bias or confounding. Alcohol drinkers may differ from nondrinkers in other ways that are known to affect cancer risk. Crockett did control for smoking and socioeconomic status but did not control for stress levels, involvement in a faith community, or prior history of alcoholism.

Practice Implications

While moderate wine drinking has cardiovascular benefits, and beer as a silica source may reduce osteoporosis risk, alcohol consumption in general has been associated with a dose-dependent increased risk of cancers of the breast, liver, esophagus, stomach, and pancreas, amongst others.¹ So, should we raise a small glass against heart disease, or pour it out against cancer?

The impact of alcohol on cancer risk is being studied most intently in relation to the gastrointestinal (GI) system, where alcohol can have its most direct impact on luminal cells. The proximal GI tract appears to be susceptible to direct toxic effects of alcohol. Crockett and others are investigating whether alcohol affects the entire GI tract similarly, or if the distal colon and rectum might respond differently than the more proximal GI organs.

In this study, those with moderate alcohol consumption appeared to derive some benefit in terms of cancer risk reduction. Moderate consumption (≤1 drink a day) decreased the risk of rectal cancer by 44%, and any amount of alcohol consumption decreased rectal cancer risk by 27%. The benefits of moderate drinking extended to the distal colon as well, with a 24% decrease in risk in beer drinkers and a 31% decrease in wine drinkers.²

While moderate wine drinking has cardiovascular benefits, and beer as a silica source may reduce osteoporosis risk, alcohol consumption in general has been associated with a dose-dependent increased risk of cancers.

Crockett isn’t the only one to report a cancer-protective effect for moderate alcohol consumption. Other studies support a dose-response relationship that may include a neutral or protective effect from moderate drinking. The Iowa Women’s Health Study found no association between moderate alcohol consumption and risk of colorectal cancer in postmenopausal women. Notably, the researchers defined “moderate drinking” as <4 grams alcohol a day, which is less than one-third of a standard drink.^3,4 At the other end of the dosing curve, a Danish study examined the effect of high consumption of wine vs other forms of alcohol. Using data from a large cohort of heavy drinkers, the study reported a 250% increase in colorectal cancer risk for those drinking beer and spirits without wine, compared to an 80% increase in risk if the alcohol included at least 30% wine. Although there was an increase in risk with heavy drinking of any alcohol, the difference between wine and spirits or beer was profound: Wine drinkers consuming >41 drinks per week had less cancer risk than beer and spirits drinkers consuming >14 drinks per week.⁵ This implies that while the alcohol may raise risk in high amounts, the wine may have mitigating ingredients that lessen the overall effect of the alcohol.

It is possible that any protection afforded from wine is due to known preventative phytochemicals such as resveratrol. Resveratrol is the polyphenol presumed responsible for the health benefits of wine on cardiovascular risk. It is possible that resveratrol is efficiently delivered to cells of the rectum and distal colon due to the extensive vascularity of the tissue. Of course, compared to how it affects the esophagus or stomach, alcohol is expected to cause less damage in the sigmoid colon and rectum since these areas are beyond the site of direct alcohol toxicity to luminal cells.

Gender may also be relevant. Crockett controlled for gender and body mass index but did not specifically analyze the impact of alcohol by gender. Other authors have explored gender differences in alcohol consumption and cancer risk. There is general consensus that women’s threshold for the amount of alcohol ingested without raising cancer risk is much lower than that of men.⁶ The Centers for Disease Control and Prevention (CDC) recommends that those who drink do so in “moderation.” According to the CDC, “Moderation is defined as the consumption of up to 1 drink per day for women and up to 2 drinks per day for men. Twelve fluid ounces of regular beer, 5 fluid ounces of wine, or 1.5 fluid ounces of 80-proof distilled spirits count as 1 drink for purposes of explaining moderation.”⁷ It should be noted that as little as 1 drink daily has been associated with increased breast cancer risk in women.⁷

Alcohol may also exert effects in the colon by impacting metabolism of other nutrients. A study of colorectal cancer in postmenopausal women found that drinking alcohol increased both the carcinogenic effects of heme iron and the cancer protective effects of dietary zinc.⁸ So, wine with a salad may have different health effects than wine with a steak. Folate intake may also modulate the effects of alcohol. In the Danish cohort, dietary folate, but not folate supplements, protected against alcohol-induced carcinogenesis for alcohol intakes of >10 grams daily.⁹ On the other hand, high alcohol consumption with low dietary folate intake is associated with a hypomethylated and more aggressive colorectal tumor type.¹⁰

In advising patients on alcohol consumption, I use the CDC standards for moderate drinking of up to 1 drink a day for women and up to 2 drinks a day for men.⁷ I also advise drinkers to enjoy their wine with whole foods, as good nutrition may optimize any beneficial health effects of wine.^8,9,10 Heavy drinking is clearly associated with multiple health consequences, including cancer. However, the Crockett study and other papers support the possibility that moderate drinking, especially of wine, may have neutral or cancer-protective effects, at least for the distal colon and rectum.^2,3,5,8

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