Lactation and risk of endometrial cancer in Japan: a case-control study.
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.
Okamura
Chikako
C
Department of Obstetrics and Gynecology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Tsubono
Yoshitaka
Y
Ito
Kiyoshi
K
Niikura
Hitoshi
H
Takano
Tadao
T
Nagase
Satoru
S
Yoshinaga
Kohsuke
K
Terada
Yukihiro
Y
Murakami
Takashi
T
Sato
Shinji
S
Aoki
Daisuke
D
Jobo
Toshiko
T
Okamura
Kunihiro
K
Yaegashi
Nobuo
N
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