Moderate Alcohol Consumption May Lower the Risk for Thyroid Cancer
Commentary by Abhijit Sen, PhD and Elizabeth N. Pearce, MD
New findings from a large prospective cohort add support to the hypothesis that moderate alcohol consumption may lower the risk of papillary and follicular thyroid carcinomas, according to a study in the British Journal of Cancer.
“This study suggests that moderate alcohol consumption may be associated with a lower risk of developing papillary and follicular thyroid carcinoma,” said lead author Abhijit Sen, PhD, Postdoctoral Researcher in the Department of Public Health and Practice at the Norwegian University of Science and Technology in Trondheim, Norway. “The cause for this ‘protective’ effect is not fully understood and is potentially complex.”
Previous studies have questioned whether alcohol has a direct effect on the thyroid or creates a disturbance of the hypothalamus-pituitary-thyroid axis, Dr. Sen noted, adding that the potential effects should be considered speculative.
Large Prospective Study
The researchers examined the association between alcohol consumption at recruitment and over the lifetime and differentiated thyroid cancer risk in 477,263 people (70% female; mean age, 51 years) in the European Prospective Investigation into Cancer and Nutrition (EPIC). At enrollment, 14% percent of the subjects reported not drinking any alcohol, 35% drank 0.1-4.9 g per day, 27% drank 5.0-14.9 g per day, and 25% consumed ≥15 g of alcohol per day,
During a mean follow up of 11 years, 556 people (90% women) were diagnosed with differentiated thyroid carcinoma. The majority of these cancers were papillary cancer (78%), followed by follicular cancer (14%), and unknown/other thyroid cancers (8%).
“Participants who consumed 15 g or more of alcohol per day (approximately 1-1.5 drinks) had a 23% reduced risk for differentiated thyroid carcinoma risk for differentiated thyroid cancer compared to those patients who consumed only 0.1 to 4.9 g of alcohol per day, when adjusted for all potential confounders (hazard ratio, 0.77),” Dr. Sen said. The risk for thyroid cancer was similar among participants who did not consume alcohol and among those who consumed 0.1 to 4.9 g per day.
“We also observed that for each 10 g per day increase in alcohol consumption there was 9% decreased risk for thyroid cancer (hazard ratio, 0.91). The association was not altered by lifetime alcohol intake or by type of alcohol beverages (beer, wine or liquor),” Dr. Sen noted.
Strengths and Limitations of the Study
“The results of this study are in agreement with the findings of several previous observational cohorts,” noted Elizabeth N. Pearce, MD, in a commentary on the study published in Clinical Thyroidology. “The strengths of this study include its large sample size and prospective study design. Its limitations include the possibility of incomplete outcomes ascertainment using cancer registry data and the fact that some tumor types and tumor staging were not known,” said Dr. Pearce, who is Associate Professor of Medicine at Boston University School of Medicine.
Dr. Pearce also noted that while many potential covariates were accounted for in the analyses (ie, age, sex, study center, smoking, education, use of hormone replacement therapy or oral contraceptives, age at menarche, number of full-term pregnancies, menopausal status), “there is a strong likelihood of residual confounding.”
Because most women in the EPIC cohort consumed low to moderate amounts of alcohol at enrollment or over their lifetimes, the researchers noted that they could not analyze the effects of heavy sustained alcohol consumption on the subsequent risk of thyroid carcinoma are unknown.
Limited Alcohol Consumption Is Recommended
Dr. Sen emphasized that, despite the findings in the current study, alcohol has been linked to an increased risk for a variety of other cancer types and patients should limit alcohol consumption to 2 drinks per day for men and 1 drink per day for women, as recommended by the World Cancer Research Fund/American Institute for Cancer Research.
November 18, 2015