title: Lactation and risk of endometrial cancer in Japan: a case-control study.
abstract: The incidence of endometrial cancer is rapidly increasing in Japan. Although the risk factors in European populations have been well described, there are few epidemiologic studies regarding risk factors for endometrial cancer in Japanese women. This hospital-based case-control study among Japanese women was carried out from 1998 to 2000. The cases were selected from women with endometrial cancer (n =155), and the controls selected from women attending the university gynecological outpatient clinic for cervical cancer screening (n = 96). Subjects were interviewed to ascertain breast feeding practices, contraceptive usage, as well as potential risk factors for endometrial cancer. We observed a lower risk of endometrial cancer associated with oral contraceptive (OC) and a higher risk associated with higher body mass index (BMI), and older ages at first and last delivery. Gravidity reduced odds ratio (OR) for endometrial cancer to 0.34 (95% confidence interval [CI] 0.13-0.92). Compared with parous women who had never breastfed, the multivariate OR for women with a history of breastfeeding was 0.37 (95% CI, 0.17-0.82). Additionally, a greater lapse of time since breastfeeding increased OR for endometrial cancer by over three times. In conclusion, the present study has indicated that breastfeeding reduces the risk of endometrial cancer in Japanese women.
authors.affiliation: Department of Obstetrics and Gynecology, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Okamura
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Tsubono
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ito
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Niikura
authors.forename: Tadao
authors.initials: T
authors.lastname: Takano
authors.forename: Satoru
authors.initials: S
authors.lastname: Nagase
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Yoshinaga
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Terada
authors.forename: Takashi
authors.initials: T
authors.lastname: Murakami
authors.forename: Shinji
authors.initials: S
authors.lastname: Sato
authors.forename: Daisuke
authors.initials: D
authors.lastname: Aoki
authors.forename: Toshiko
authors.initials: T
authors.lastname: Jobo
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Okamura
authors.forename: Nobuo
authors.initials: N
authors.lastname: Yaegashi
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003267:Contraception; D016889:Endometrial Neoplasms / Q000453:epidemiology*; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007774:Lactation; D008875:Middle Aged; D012307:Risk Factors