{"title":"Body mass index and breast cancer risk in premenopausal and postmenopausal East Asian women: a pooled analysis of 13 cohort studies.","authors":"Keiko Wada, Koshi Kuboyama, Sarah Krull Abe, Md Shafiur Rahman, Md Rashedul Islam, Eiko Saito, Chisato Nagata, Norie Sawada, Akiko Tamakoshi, Xiao-Ou Shu, Ritsu Sakata, Atsushi Hozawa, Seiki Kanemura, Hidemi Ito, Yumi Sugawara, Sue K Park, Sun-Seog Kweon, Ayami Ono, Takashi Kimura, Wanqing Wen, Isao Oze, Min-Ho Shin, Aesun Shin, Jeongseon Kim, Jung Eun Lee, Keitaro Matsuo, Nathaniel Rothman, You-Lin Qiao, Wei Zheng, Paolo Boffetta, Manami Inoue","doi":"10.1186/s13058-024-01907-5","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong>It has been suggested that the association between body mass index and breast cancer risk differs between Asian women and Western women. We aimed to assess the associations between body mass index and breast cancer incidence in East Asian women.</p><p><strong>Methods: </strong>Pooled analyses were performed using individual participant data of 319,189 women from 13 cohort studies in Japan, Korea, and China. Participants' height and weight were obtained by measurement or self-reports at cohort baseline. Breast cancer was defined as code C50.0-C50.9 according to the International Classification. Using a Cox proportional hazards model, hazard ratios of breast cancer were estimated for each body mass index category, with the reference group set as the group with a body mass index of 21 to < 23 kg/m<sup>2</sup>. The hazard ratio for a 5 kg/m<sup>2</sup> increase in body mass index was also calculated.</p><p><strong>Results: </strong>During a mean 16.6 years of follow-up, 4819 women developed breast cancer. Similar to Westerners, a steady increase in breast cancer risk with increasing body mass index was observed in postmenopausal women, but the slope of the risk increase appeared to slow at a body mass index of 26-28 kg/m<sup>2</sup>. In premenopausal women, the inverse association seen in Westerners was not observed. The risk of developing breast cancer after 50 years of age increased slightly with increasing body mass index, which was more pronounced in the older birth cohort. There was no significant association between body mass index and the risk of developing breast cancer before 50 years of age, but the risk estimates changed from positive to negative as the birth cohort got younger.</p><p><strong>Conclusions: </strong>In East Asia, the role of body mass index in breast cancer in premenopausal women may be changing along with the increase in obesity and breast cancer. The increased risk of postmenopausal breast cancer with a higher body mass index was as robust as that of Western women.</p>","PeriodicalId":49227,"journal":{"name":"Breast Cancer Research","volume":"26 1","pages":"158"},"PeriodicalIF":7.4000,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11566150/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Breast Cancer Research","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1186/s13058-024-01907-5","RegionNum":1,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"Medicine","Score":null,"Total":0}
引用次数: 0
Abstract
Background: It has been suggested that the association between body mass index and breast cancer risk differs between Asian women and Western women. We aimed to assess the associations between body mass index and breast cancer incidence in East Asian women.
Methods: Pooled analyses were performed using individual participant data of 319,189 women from 13 cohort studies in Japan, Korea, and China. Participants' height and weight were obtained by measurement or self-reports at cohort baseline. Breast cancer was defined as code C50.0-C50.9 according to the International Classification. Using a Cox proportional hazards model, hazard ratios of breast cancer were estimated for each body mass index category, with the reference group set as the group with a body mass index of 21 to < 23 kg/m2. The hazard ratio for a 5 kg/m2 increase in body mass index was also calculated.
Results: During a mean 16.6 years of follow-up, 4819 women developed breast cancer. Similar to Westerners, a steady increase in breast cancer risk with increasing body mass index was observed in postmenopausal women, but the slope of the risk increase appeared to slow at a body mass index of 26-28 kg/m2. In premenopausal women, the inverse association seen in Westerners was not observed. The risk of developing breast cancer after 50 years of age increased slightly with increasing body mass index, which was more pronounced in the older birth cohort. There was no significant association between body mass index and the risk of developing breast cancer before 50 years of age, but the risk estimates changed from positive to negative as the birth cohort got younger.
Conclusions: In East Asia, the role of body mass index in breast cancer in premenopausal women may be changing along with the increase in obesity and breast cancer. The increased risk of postmenopausal breast cancer with a higher body mass index was as robust as that of Western women.
期刊介绍：
Breast Cancer Research, an international, peer-reviewed online journal, publishes original research, reviews, editorials, and reports. It features open-access research articles of exceptional interest across all areas of biology and medicine relevant to breast cancer. This includes normal mammary gland biology, with a special emphasis on the genetic, biochemical, and cellular basis of breast cancer. In addition to basic research, the journal covers preclinical, translational, and clinical studies with a biological basis, including Phase I and Phase II trials.
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