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Reproductive Factors Related to Serum Estrogen, Progesterone, and Sex Hormone Binding Globulin in Postmenopausal Women in Korea.
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Chul Hwan Kim, Sue Kyung Park, Heon Kim, Mi Na Ha, Hai Rim Shin, Bu Ok Lee, Dae Sung Kim, Dae Hee Kang, Keun Young Yoo
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Korean J Epidemiol. 1998;20(1):70-81.
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Abstract
The etiology of breast cancer is not yet clear. Several epidemiologic studies have supported the concepts that endogenous female sex hormones, i.e., estrogen and progesterone, may play a central role in the development of breast cancer. Female reproductive factors such as menstruation, pregnancy, and breast feeding are well-known risk factors of breast cancer. There have been many suggestions that all these factors are midiated by female sex hormeones. However, only a few studies have evaluated the relationship between the reproductive factors and endogenous female sex hormones. This study was designed to evaluate the relationship between the reproductive factors and endogenous female sex hormones in Korean women. We analyzed the relationship between reproductive factors and female sex hormones in 153 premenopausal women 153 postmenopausal women who participated in a community health promotion program in Haman County, Korea. The questionnaires about reproductive factors were completed by personal interview. Serum level of total estradiol(E2), progesterone(:g), and sex hormone binding globulin(SHBG) were measured by radioimmunoassay. There was no significant correlation between age at menarche and E2 in both premenopausal and postmenopausal groups. In postmenopausal subjects, E2 level increased significantly with the age at menopause increasing(r=0.25, p=0.009), adjusting for the potential confounding effect of both age and body mass index. There was a positive correlation between E2 and the intervals between age at menarche and age at menopause(r=0.25, p=0.009). Moreover, the serum level of SHBG was significantly correlated with total months of breast feeding(r=0.19, p=0.048), as well as with age at first fullterm pregnancy(r=-0.24, p=0.01). However, Pg was correlated with none of reproductive factors in both groups.
This study observed that female reproductive factors, e.g., age at menopause, breast feeding, age at first fullterm pregnancy, were correlated with serum female hormones, particularly E2 and SHBG. The results provide an evidence that the relationship between the reproductive factors and breast cancer risk may be mediated, at least in part, through serum female hormones, especially estradiol in Korean women.
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A stochastic analysis on the force of infection by hepatitis B virus in Korea.
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Keun Young Yoo, Moo Song Lee, Youngjo Lee, Bo Youl Choi, Heon Kim, Yong Sik Kim
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Korean J Epidemiol. 1992;14(2):128-137.
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Abstract
Hepatitis B virus infection is still one of the major health problems in Korea, because of its high prevalence and its deleterious sequellae to liver cirrhosis and hepatocellular carcinoma. However, little is known about incidence (force of infection) of the viral infection. Investigation on the natural history of the virus, such as age-dependency of occurrence, is thus necessary to establish the efficient measures of prevention and management. This study was done to estimate the incidence of hepatitis B virus infection, as well as to assess the prevalent age group of the infection through a stochastic analysis using mathematical models. Data on positivity of hep¬atitis B virus markers (HBsAg, anti-HBs,anti-HBc) were obtained from two different population; a typical rural population in Kyunggi province (n=741) and a health insurance beneficiaries in the Seoul City (n=726). As results, force of infection by the virus was decreasing until the age group around 20, and afterwards remained stationary. The annual incidence of the infection was 15 per 100 persons at birth, 5 per 100 persons at the age, of 10, and about 3 per 100 persons after the age of 20. Proportion of antigen positivity among persons infected by the virus was also decreasing with age increasing. These results suggest that new infection of hepatitis B virus mostly occurs early in life in Korea, resulting in subsequent high prevalence of the infection.
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