BACKGROUND Reproductive factors and hormone use in postmenopausal women have been hypothesised to affect the risk of developing lung cancer, but the epidemiological evidence is inconsistent. METHODS Using the Korean National Health Insurance System database, we identified 4,775,398 postmenopausal women older than 40 years who had undergone both cardiovascular health- and cancer screening between 1 January 2009 and 31 December 2014. Information about reproductive factors was obtained from a self-administered questionnaire. The risk of lung cancer was estimated using Cox proportional hazard regression models. RESULTS During a median follow-up of 4.4 years, 16,556 women (15,223 non-smokers) were diagnosed with lung cancer. The risk of lung cancer was not significantly influenced by early menarche age (adjusted hazard ratio [aHR] 1.03 for menarche ≥18 vs. ≤14; 95% confidence interval [CI], 0.98-1.09) or late age at menopause (aHR 1.02 for menopause ≥55 vs. <40; 95% CI, 0.91-1.14). Furthermore, the number of children, duration of breastfeeding and use of hormone replacement therapy were not associated with the risk of lung cancer. CONCLUSIONS No statistically significant association was found between reproductive factors and the risk of lung cancer in postmenopausal Korean women.

中文翻译：

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绝经后妇女的女性生殖因子和患肺癌的风险：一项全国性队列研究。

背景技术已假设绝经后妇女中的生殖因子和激素的使用会影响患肺癌的风险，但流行病学证据不一致。方法使用韩国国民健康保险系统数据库，我们鉴定了4,775,398名40岁以上的绝经后妇女，她们在2009年1月1日至2014年12月31日期间接受了心血管健康和癌症筛查。有关生殖因子的信息来自自我管理的问卷。使用Cox比例风险回归模型评估肺癌的风险。结果在4.4年的中位随访中，诊断出16,556名妇女（15,223名非吸烟者）患有肺癌。初潮年龄未显着影响肺癌的风险（调整后的危险比[aHR] 1。初潮≥18vs≤14为03；95％的置信区间[CI]为0.98-1.09）或更年期的晚龄（绝经期≥55vs. <40的aHR 1.02； 95％CI为0.91-1.14）。此外，儿童的数量，母乳喂养的持续时间和激素替代疗法的使用与患肺癌的风险无关。结论绝经后韩国女性的生殖因素与肺癌风险之间没有统计学意义的关联。