Background The incidence of differentiated thyroid cancer (DTC) is higher in women than in men but whether sex steroid hormones contribute to this difference remains unclear. Studies of reproductive and hormonal factors and thyroid cancer risk have provided inconsistent results. Methods Original data from 1 252 907 women in 16 cohorts in North America, Europe, Australia and Asia were combined to evaluate associations of DTC risk with reproductive and hormonal factors. Multivariable-adjusted Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% CIs. Results During follow-up, 2142 women were diagnosed with DTC. Factors associated with higher risk of DTC included younger age at menarche (<10 vs 10–11 years; HR, 1.28; 95% CI, 1.00–1.64), younger (<40; HR, 1.31; 95% CI, 1.05–1.62) and older (≥55; HR, 1.33; 95% CI, 1.05–1.68) ages at menopause (vs 40–44 years), ever use of menopausal hormone therapy (HR, 1.16; 95% CI, 1.02–1.33) and previous hysterectomy (HR, 1.25; 95% CI, 1.13–1.39) or bilateral oophorectomy (HR, 1.14; 95% CI, 1.00–1.29). Factors associated with lower risk included longer-term use (≥5 vs <5 years) of oral contraceptives (HR, 0.86; 95% CI, 0.76–0.96) among those who ever used oral contraception and baseline post-menopausal status (HR, 0.82; 95% CI, 0.70–0.96). No associations were observed for parity, duration of menopausal hormone therapy use or lifetime number of reproductive years or ovulatory cycles. Conclusions Our study provides some evidence linking reproductive and hormonal factors with risk of DTC. Results should be interpreted cautiously considering the modest strength of the associations and potential for exposure misclassification and detection bias. Prospective studies of pre-diagnostic circulating sex steroid hormone measurements and DTC risk may provide additional insight.

中文翻译：

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激素和生殖因素与女性分化型甲状腺癌风险的关联：汇总前瞻性队列分析

背景 女性分化型甲状腺癌（DTC）的发病率高于男性，但性类固醇激素是否导致这种差异仍不清楚。关于生殖和激素因素以及甲状腺癌风险的研究提供了不一致的结果。方法 将来自北美、欧洲、澳大利亚和亚洲 16 个队列的 1 252 907 名女性的原始数据结合起来，评估 DTC 风险与生殖和激素因素的关联。使用多变量调整的 Cox 比例风险模型来估计风险比 (HR) 和 95% CI。结果在随访期间，2142 名女性被诊断患有 DTC。与 DTC 风险较高相关的因素包括初潮年龄较年轻（<10 岁 vs 10-11 岁；HR，1.28；95% CI，1.00-1.64）、较年轻（<40；HR，1.31；95% CI，1.05） –1.62) 及以上 (≥55; HR, 1.33; 95% CI, 1.05–1.68) 绝经年龄 (vs 40–44 岁)，曾经使用过绝经激素治疗 (HR, 1.16; 95% CI, 1.02–1.33 ）和既往子宫切除术（HR，1.25；95% CI，1.13–1.39）或双侧卵巢切除术（HR，1.14；95% CI，1.00–1.29）。与较低风险相关的因素包括曾经使用过口服避孕药的患者长期使用口服避孕药（≥5 年 vs <5 年）（HR，0.86；95% CI，0.76-0.96）以及基线绝经后状态（HR，0.86；95% CI，0.76-0.96）。 ，0.82；95% CI，0.70–0.96）。没有观察到胎次、绝经激素治疗使用持续时间或一生生育年数或排卵周期之间的关联。结论 我们的研究提供了一些将生殖和激素因素与 DTC 风险联系起来的证据。考虑到相关性的适度强度以及暴露错误分类和检测偏差的可能性，应谨慎解释结果。对诊断前循环性类固醇激素测量和 DTC 风险的前瞻性研究可能会提供更多见解。