Importance: Despite evidence of an association between reproductive factors and endometrial cancer risk, prospective studies have been conducted mainly in non-Asian countries.
Objective: To assess the association between reproductive factors, such as number of deliveries, age at menarche, or menopause, and endometrial cancer risk.
Design, Setting, and Participants: This cohort study used pooled individual data from 13 prospective cohort studies conducted between 1963 and 2014 in the Asia Cohort Consortium. Participants were Asian women. Data analysis was conducted from September 2019 to April 2023. Exposures: Reproductive factors were assessed using a questionnaire in each cohort.
Main Outcomes and Measures: The main outcome was time to incidence of endometrial cancer. A Cox proportional hazards model was used to calculate hazard ratios (HRs) and 95% CIs.
Results: A total of 1005 endometrial cancer cases were detected among 332 625 women (mean [SD] age, 54.3 [10.4] years) during a mean (SD) of 16.5 (6.4) years of follow-up. Increasing number of deliveries was associated with a decreased endometrial cancer risk in a dose-response manner (≥5 deliveries vs nulliparous [reference]: HR, 0.37; 95% CI, 0.26-0.53; P for trend < .001). Compared with menarche at younger than 13 years, menarche at 17 years or older had an HR of 0.64 (95% CI, 0.48-0.86; P for trend < .001). Late menopause (age ≥55 years) showed an HR of 2.84 (95% CI, 1.78-4.55; P for trend < .001) compared with the youngest age category for menopause (<45 years). Age at first delivery, hormone therapy, and breastfeeding were not associated with endometrial cancer risk.
Conclusions and Relevance: This large pooled study of individual participant data found that late menarche, early menopause, and a higher number of deliveries were significantly associated with a lower risk of endometrial cancer. These convincing results from Asian prospective studies add to the growing body of evidence for the association between reproductive factors and endometrial cancer.
Title
Reproductive Factors and Endometrial Cancer Risk Among Women
Author
Katagiri, Ryoko : National Cancer Center Institute for Cancer Control
Iwasaki, Motoki : National Institutes of Biomedical Innovation
Abe, Sarah Krull : National Cancer Center Institute for Cancer Control
Islam, Md Rashedul : National Cancer Center Institute for Cancer Control
Rahman, Md Shafiur : National Cancer Center Institute for Cancer Control
Saito, Eiko : National Center for Global Health and Medicine
Merritt, Melissa A. : University of Sydney
Choi, Ji-Yeob : Seoul National University
Shin, Aesun : Seoul National University
Sawada, Norie : National Cancer Center Institute for Cancer Control
Tamakoshi, Akiko : Hokkaido University
Koh, Woon-Puay : National University of Singapore
Sakata, Ritsu : Radiation Effects Research Foundation
Tsuji, Ichiro : Tohoku University
Kim, Jeongseon : National Cancer Center
Nagata, Chisato : Gifu University
Park, Sue K. : Seoul National University
Kweon, Sun-Seog : Chonnam National University
Shu, Xiao-Ou : Vanderbilt University
Gao, Yu-Tang : Shanghai Cancer Institute
Tsugane, Shoichiro : National Cancer Center Institute for Cancer Control
Kimura, Takashi : Hokkaido University
Yuan, Jian-Min : University of Pittsburgh
Kanemura, Seiki : Tohoku University
Lu, Yukai : Tohoku University
Sugawara, Yumi : Tohoku University
Wada, Keiko : Gifu University
Shin, Min-Ho : Chonnam National University
Ahsan, Habibul : University of Chicago
Content Type
Article
Published in
JAMA Network Open
Data availability statement
See Supplement 2.
Funding Information
National Cancer Institute, R37 CA070867
National Cancer Institute, UM1 CA182910
Japan Public Health Center
National Cancer Center, Research and Development Fund, 23-A-31
National Cancer Center, Research and Development Fund, 26-A-4
National Cancer Center, Research and Development Fund, 2020-A-4
Ministry of Health, Labour and Welfare of Japan, grant-in-aid for Cancer Research
Ministry of Health, Labour and Welfare, Japan, grants for health service and comprehensive research on cardiovascular and lifestyle related diseases
Ministry of Education, Culture, Sports, Science and Technology, Japan, grant for scientific research
Ministry of Science, ICT and Future Planning, 2016R1A2B4014552
National Cancer Center, 1510040
National Cancer Center, 1810090
National Cancer Center, 1910330
National Cancer Institute, R01CA144034
National Cancer Institute, UM1CA182876
Publication Date
2023-09-05
Language
English
Notes
Due to the large number of authors, only the first 20 and the University of Chicago authors are included on the above author list. Please download the article for the complete list of authors.
Record Created
2024-02-23