Female Thyroid Cancer: The Role of Reproductive and Hormonal Factors in Switzerland

Abstract

We conducted a study on 91 women with thyroid cancer and 306 controls in hospital for acute nonneoplastic, non-hormone-related disorders in order to investigate the role of reproductive and hormonal factors in the etiology of epithelial thyroid cancer in the Canton of Vaud, Switzerland. Non-significant increases in cancer risk with an increasing number of full-term pregnancies (odds ratio, OR, after allowance for age and previous benign thyroid disease = 1.6, for > 3 vs. 0 full-term pregnancies, 95% confidence interval, CI: 0.7–3.6) and spontaneous abortions (OR = 2.0 for > 2 vs. 0 spontaneous abortions, 95% CI: 0.7–5.2) were seen. A significantly elevated OR (2.8,95% CI: 1.1–7.2) was found in those women whose first pregnancy ended with an abortion. Whereas most other reproductive, menstrual and hormonal factors examined did not seem to affect the risk of thyroid cancer significantly, a clue emerged of an association between thyroid cancer and artificial menopause (OR = 6.3, for women who underwent artificial menopause vs. premenopausal women, 95% CI: 1.7–23.2). Although not necessarily causal, the relationship between the risk of epithelial thyroid cancer and the occurrence of spontaneous abortions and artificial menopause deserves attention in future studies, in the light of the high incidence of thyroid cancer in young and middle-aged women.

Epidemiology of reproductive and hormonal factors in thyroid cancer: Evidence from a case‐control study in the Middle East

“…An increased risk of similar magnitude was reported in a study from Italy (relative risk (RR) ϭ 2.2; 95% CI: 1.3-3.7 for women aged Ն30 years at last birth); 25 whereas, no association was found in studies from Switzerland 26 and Washington State in the US. 27 In a nested case-control study of a nation-wide Swedish cohort, there was a significant trend in excess risk among women who had a live birth at ages Ն25 years (OR ϭ 1.6; 95% CI: 1.1-2.5 for women aged Ն35 years at last birth).…”

“…For history of spontaneous or induced abortion, the data are conflicting; with some reports of increased risk of thyroid cancer with history of miscarriage or abortion, particularly as an outcome of first pregnancy 26,[31][32][33]37 and others of none. 29,38,39,41 Moreover, a decreased risk was found in a study from Italy for women who had ever experienced an abortion (RR ϭ 0.6; 95% CI: 0.4 -1.0).…”

A Case-control Study in Hiroshima and Nagasaki Examining Non-radiation Risk Factors for Thyroid Cancer

“…18 Although not all, [19][20][21][22] several previous studies of thyroid cancer have reported a reduced risk of thyroid cancer significantly, [23][24][25][26] or not significantly associated with cigarette smoking. [27][28][29][30][31][32][33] Although results are less consistent, 20,22,24,29,[31][32][33] several studies have also suggested reduced thyroid cancer risk associated with alcohol drinking. 19,25,27,31,34 A number of possible mechanisms have been suggested.…”

Risk factors for thyroid cancer: A prospective cohort study

“…[28][29][30][31][32][33][34][35][36][37][38][39] Although 8 studies reported odds ratios above unity (comparing parous vs. nulliparous), [28][29][30]32,34,[36][37][38] only one of these findings was statistically significant. 38 However, a pooled analysis of 12 case-control studies (including unpublished data from a case-control study conducted in Nagasaki, Japan) found a borderline increased risk when comparing parous vs. nulliparous women (OR 5 1.2; 95% CI 5 1.0-1.6).…”

“…Unlike the pooled analysis of case-control data 15 and the results reported by Akslen et al 18 and Kravdal et al, 19 which reported no association between parity and papillary thyroid cancer, we observed an inverse association among women with 5 or more live births compared to nulliparous women. Multivariate adjusted for age (time to event variable), HRT use (ever/never), study center and randomization group (intervention vs. control).-Of the 12 published case-control studies that have examined age at first birth as a risk factor for thyroid cancer, [28][29][30][31][32][34][35][36][37][38][39][40] 10 reported an OR above unity in women with a relatively late age at first birth (age at first birth modeled continuously, based on a unit increase of 5 years). 28,29,31,32,[34][35][36][37]39,40 Using pooled data from 12 case-control studies (including unpublished case-control data from Nagasaki, Japan), Negri et al 15 reported a statistically significant increased risk of thyroid cancer for women at or above 30 years of age at first birth compared to women below age 20 at first birth (OR 5 1.8; 95% CI 5 1.0-1.8).…”