Hormonal and body-size factors in relation to breast cancer risk: a prospective study of 11,889 women in a low-incidence area.
OBJECTIVE
This prospective cohort study of 11,889 women was conducted to determine significant factors associated with the risk of breast cancer among Chinese women in Taiwan, a low-incidence area.


METHODS
In-person interviews were completed for subjects to solicit information on hormonal factors. Measurements of height, weight, and waist-and- hip circumferences were performed by well-trained assistants using standardized techniques. Cox proportional hazards models were employed to estimate relative risks (RRs) and 95% confidence intervals (CIs).


RESULTS
During an average follow-up time of 10.3 years (range: 1 to 11 years) with an accumulation of 134,063 person-years, 104 incident breast cancer cases were identified through data linkage with national cancer registry profile. There was a significant elevation in breast-cancer risk with increasing duration of the interval between age at menarche and age at first full-term pregnancy (FFTP). Additionally, central adiposity reflected by hip circumference was a significant predictor of breast cancer in this Chinese female population.


CONCLUSIONS
The findings of this study indicated common mechanisms responsible for the higher incidence of breast cancer in Western populations may also explain the risk of breast cancer development in Taiwan, a low-incidence area.
Wu
Mei-Hsuan
MH
School of Public Health, National Defense Medical Center, Taipei 114, Taiwan, Republic of China.
Chou
Yu-Ching
YC
Yu
Jyh-Cherng
JC
Yu
Cheng-Pung
CP
Wu
Cho-Chieh
CC
Chu
Chi-Ming
CM
Yang
Tsan
T
Lai
Ching-Huang
CH
Hsieh
Chang-Yao
CY
You
San-Lin
SL
Chen
Chien-Jen
CJ
Sun
Chien-An
CA
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D049628:Body Size; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000378:metabolism; D002681:China / Q000208:ethnology; D015331:Cohort Studies; D005260:Female; D006728:Hormones / Q000378:metabolism*; D006801:Humans; D008572:Menarche; D008875:Middle Aged; D011247:Pregnancy; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology
D006728:Hormones