Risk of papillary thyroid cancer in women in relation to smoking and alcohol consumption.

Both smoking and alcohol consumption may influence thyroid function, although the nature of these relations is not well understood. We examined the influence of tobacco and alcohol use on risk of papillary thyroid cancer in a population-based case-control study. Of 558 women with thyroid cancer diagnosed during 1988-1994 identified as eligible, 468 (83.9%) were interviewed; this analysis was restricted to women with papillary histology (N = 410). Controls (N = 574) were identified by random digit dialing, with a response proportion of 73.6%. We used logistic regression to calculate odds ratios (OR) and associated confidence intervals (CI) estimating the relative risk of papillary thyroid cancer associated with cigarette smoking and alcohol consumption. A history of ever having smoked more than 100 cigarettes was associated with a reduced risk of disease (OR = 0.7, 95% CI = 0.5-0.9). This reduction in risk was most evident in current smokers (OR = 0.5, 95% CI = 0.4-0.7). Women who reported that they had ever consumed 12 or more alcohol-containing drinks within a year were also at reduced risk (OR 0.7, 95% CI = 0.5-1.0). Similar to the association noted with smoking, the reduction in risk was primarily present among current alcohol consumers. The associations we observed, if not due to chance, may be related to actions of cigarette smoking and alcohol consumption that reduce thyroid cell proliferation through effects on thyroid stimulating hormone, estrogen, or other mechanisms.

Risk of endometrial cancer in relation to use of low-dose, unopposed estrogens.

OBJECTIVE: To determine whether a low dosage (0.3 mg/day) of unopposed conjugated estrogens can be used without incurring an elevated risk of endometrial cancer. METHODS: In this case-control study, cases (n = 484) consisted of women diagnosed with endometrial cancer between 1985 and 1991 in three counties in Western Washington. Controls (n = 780) were identified using random digit dialing within the same three counties. Subjects were interviewed in person to obtain basic demographic and medical history information, as well as specific information about hormone use. RESULTS: Eighteen cases and eight controls had taken 0.3 mg/day of unopposed conjugated estrogens and no other dose or preparation of estrogens (risk relative to that of women who had not taken postmenopausal hormones = 5.4, 95% confidence interval [CI] 2.3, 13.0). The risk was particularly high in women whose use of this dose was both current and of more than 8 years' duration (odds ratio = 9.2, 95% CI 2.9, 29.0). The elevation in risk in users of 0.3 mg/day was similar in size to that associated with the daily unopposed use of 0.625 mg of conjugated estrogens. CONCLUSION: The results suggest that a dosage of 0.3 mg per day of unopposed conjugated estrogens is associated with an increased risk of endometrial cancer.