Cell proliferation in response to thyroid stimulating hormone
(TSH) may influence risk for thyroid cancer. Smoking and alcohol
use may influence TSH levels or TSH activity as well as thyroid
function, but the nature of these relations is not well understood.
In this study by Rossing MA, Cushing KL, Voigt LF, Wicklund KG
and Daling JR the relation of smoking and drinking to risk for
papillary thyroid cancer was made.
A population-based case control study of papillary thyroid cancer
involved 558 women aged 18-64 with thyroid cancer diagnosed between
1988-1994, 468 (84%) were interviewed. Analyses were confined
to women with papillary histology (n=410). Controls (n=574) were
selected by random digit dialling (response rate 73.6%) Logistic
regression analysis was used to calculate odds ratios and corresponding
confidence intervals estimating the relative risk of papillary
thyroid cancer associated with smoking and drinking. If at the
time of cancer diagnosis women used alcohol or smoked they were
considered current smokers or drinkers, for controls at a comparable
A history of ever having smoked more than 100 cigarettes was associated
with a reduced risk (OR 0.7, 95% CI 0.5-0.9) with the risk reduction
being most pronounced in current smokers (OR 0.5, 95% CI 0.4-0.7.
Women who reported they had consumed 12 or more alcoholic drinks
within a year also had a lowered risk (OR 0.7, 95% CI 0.5-1.0).
As for smoking the risk reduction was most prominent for current
drinkers. The risk reduction was greater for women aged >45 years
(OR 0.4, 95% CI 0.2-0.7) than for younger women (OR 0.8, 95% CI
The results suggest that the effects of alcohol and tobacco on
thyroid cancer risk are of relatively short duration, but the
association found, if not attributable to chance, may be related
to the effects of smoking and drinking on reducing thyroid cell
proliferation through effects on TSH, oestrogen or other mechanisms.
Source. Rossing MA, Cushing KL, Voigt LF, Wicklund KG. Risk of
papillary thyroid cancer in women in relation to smoking and alcohol
consumption. Epidemiology 11 (2000) 49-54.