Sugawara Yumi, Sugiyama Kemmyo, Tomata Yasutake, Kanemura Seiki, Fukao Akira, Tsuji Ichiro
Division of Epidemiology, Department of Health Informatics and Public Health, Tohoku University School of Public Health, Graduate School of Medicine, Sendai, Japan.
Division of Cancer Epidemiology and Prevention, Miyagi Cancer Center Research Institute, Natori, Japan.
J Cancer. 2018 Oct 27;9(23):4422-4429. doi: 10.7150/jca.26242. eCollection 2018.
Age at first birth has been increasing among women in developed countries. Meanwhile, endometrial cancer has also been increasing worldwide, being one of the most common female hormone-related cancers. The purpose of this study was to examine the association between age at first birth and the risk of endometrial cancer among Japanese women, and to examine the hypothesis that the recent increase in endometrial cancer incidence can be partly explained by the trend for increasing age at first birth. We conducted a pooled analysis of two prospective studies among residents in Miyagi Prefecture in rural northern in Japan. The Miyagi Cohort Study started in 1990 and included 21,455 parous women. The Ohsaki Cohort Study started in 1994 and included 17,287 parous women. The subjects responded to a self-administrated questionnaire including reproductive factors such as age at first birth. Incident cases of cancer were identified through linkage to the Miyagi Prefectural Cancer Registry, which covers the study area. In a consortium of two prospective studies with 598,933 person-years, we identified 105 incident case of endometrial cancer. Compared with women aged 22 years or less at first birth, multivariate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of endometrial cancer were 0.79 (0.49-1.26) for women aged 23 to 25 years at first birth, and 0.53 (0.28-1.00) for those aged 26 years and older <0.05). This pooled analysis of two prospective studies does not support the hypothesis that the recent increase in the incidence of endometrial cancer can be partly explained by the increase in the age at first birth.
在发达国家，女性的初育年龄一直在上升。与此同时，子宫内膜癌在全球范围内也呈上升趋势，是最常见的女性激素相关癌症之一。本研究的目的是调查日本女性的初育年龄与子宫内膜癌风险之间的关联，并检验以下假设：子宫内膜癌发病率近期的上升部分可归因于初育年龄增加的趋势。我们对日本北部农村宫城县居民的两项前瞻性研究进行了汇总分析。宫城队列研究始于1990年，纳入了21455名经产妇女。大崎队列研究始于1994年，纳入了17287名经产妇女。研究对象对一份包括初育年龄等生殖因素的自填问卷进行了回答。通过与覆盖研究区域的宫城县癌症登记处建立联系，确定癌症发病病例。在一项包含598933人年的两项前瞻性研究的联合分析中，我们确定了105例子宫内膜癌发病病例。与初育年龄在22岁及以下的女性相比，初育年龄在23至25岁的女性患子宫内膜癌风险的多变量风险比（HR）和95%置信区间（CI）为0.79（0.49 - 1.26），初育年龄在26岁及以上的女性为0.53（0.28 - 1.00）（P<0.05）。这两项前瞻性研究的汇总分析不支持以下假设：子宫内膜癌发病率近期的上升部分可由初育年龄的增加来解释。
