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Low to moderate alcohol consumption in women increases the risk of certain cancers

http://jnci.oxfordjournals.org/cgi/content/abstract/djn514 

Moderate Alcohol Intake and Cancer Incidence in Women

Naomi E. AllenValerie BeralDelphine CasabonneSau Wan Kan,Gillian K. ReevesAnna BrownJane Green
on behalf of the Million Women Study Collaborators

Affiliation of authors: Cancer Epidemiology Unit, University of Oxford, Oxford, UK

Correspondence to: Dr Naomi E. Allen, Cancer Epidemiology Unit, University of Oxford, Richard Doll Building, Oxford OX3 7LF, UK (e-mail: naomi.allen@ceu.ox.ac.uk).

Background: With the exception of breast cancer, little is known about the effect of moderate intakes of alcohol, or of particular types of alcohol, on cancer risk in women.

Methods: A total of 1 280 296 middle-aged women in the United Kingdomenrolled in the Million Women Study were routinely followed for incident cancer. Cox regression models were used to calculate adjusted relative risks and 95% confidence intervals (CIs) for 21 site-specific cancers according to amount and type of alcoholic beverage consumed. All statistical tests were two-sided.

Results: A quarter of the cohort reported drinking no alcohol; 98% of drinkers consumed fewer than 21 drinks per week, with drinkers consuming an average of 10 g alcohol (1 drink) per day. During an average 7.2 years of follow-up per woman 68 775 invasive cancers occurred. Increasing alcohol consumption was associated with increased risks of cancers of the oral cavity and pharynx (increase per 10 g/d = 29%, 95% CI = 14% to 45%, Ptrend < .001), esophagus (22%, 95% CI = 8% to 38%, Ptrend = .002), larynx (44%, 95% CI = 10% to 88%, Ptrend = .008), rectum (10%, 95% CI = 2% to 18%, Ptrend = .02), liver (24%, 95% CI = 2% to 51%, Ptrend = .03), breast (12%, 95% CI = 9% to 14%,Ptrend < .001), and total cancer (6%, 95% CI = 4% to 7%, Ptrend < .001). The trends were similar in women who drank wine exclusively and other consumers of alcohol. For cancers of the upper aerodigestive tract, the alcohol-associated risk was confined to current smokers, with little or no effect of alcohol among never and past smokers(Pheterogeneity < .001). Increasing levels of alcohol consumption were associated with a decreased risk of thyroid cancer (Ptrend = .005), non–Hodgkin lymphoma (Ptrend = .001), and renal cell carcinoma (Ptrend = .03).

Conclusions: Low to moderate alcohol consumption in women increases the risk of certain cancers. For every additional drink regularly consumed per day, the increase in incidence up to age 75 years per 1000 for women in developed countries is estimated to be about 11 for breast cancer, 1 for cancers of the oral cavity and pharynx, 1 for cancer of the rectum, and 0.7 each for cancers of the esophagus, larynx and liver, giving a total excess of about 15 cancers per 1000 women up to age 75.



Context and Caveats

Prior knowledge

With the exception of breast cancer, there was little information on the cancer risks conferred by alcohol consumption in women.

Study design

Prospective cohort study with alcohol consumption determined on the basis of a questionnaire and information on incidence of specific cancers obtained from a national registry. Cox regression models were used to estimate cancer risks associated with alcohol consumption after adjustment for other risk factors.

Contribution

Increasing but moderate alcohol consumption in women was determined to be associated with an increased risk of cancers of the oral cavity and pharynx, esophagus, larynx, rectum, breast, and liver, and with a decreased risk for thyroid cancer, non–Hodgkin lymphoma, and renal cell carcinoma. No differences in cancer risks were observedbetween drinkers of wine only and other consumers of alcohol.

Implications

In middle-aged women, moderate alcohol consumption increases the risk of cancer overall; each additional drink regularly consumed per day may account for approximately 15 excess cancers per 1000 women up to age 75 in this age group in developed countries.

Limitations

The study could not address the risk conferred by heavy sustained drinking due to the composition of the cohort.

From the Editors

 
Manuscript received April 7, 2008; revised October 20, 2008; accepted December 18, 2008.

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