Epidemiology of Breast Cancer in Korea: Occurrence, High-Risk Groups, and Prevention

Breast cancer ranks second or third to uterine cervix cancer and stomach cancer as a cause of death in women, and as a common site of primary cancer. The large difference in its incidence between Westernized and non-Westernized countries is remarkable. There is a linear increase with age that is observed in Western countries, which are high-incidence areas, on the contrary to the inverted V shape curve seen in Asian countries. Epidemiologic studies conducted in Korea have shown that an older age, a family history of breast cancer, early menarche, late menopause, late full-term pregnancy, and never having had a breast-fed child are primary risk factors in the development of breast cancer. The estrogen-augmented-by-progesterone hypothesis explains the roles of these factors to some extent. On the other hand, recent molecular studies have revealed the existence of novel gene environmental interactions. Epidemiological features suggest that the breast cancer incidence rate in Korea will increase, but the age specific curve would not be changed in keeping with what is observed in Western countries. Strategies aimed at controlling breast cancer that include the screening guidelines and the identification of individual predispositions may give us further insights into both the etiology and the prevention of breast cancer.

Glutathione S-transferase P1 Genetic Polymorphisms and Breast Cancer Risk / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: To evaluate the potential association between the GSTP1 genotype and the development of breast cancer, a hospital based case-control study was conducted in South Korea. MATERIALS AND METGODS: The study population consisted of 171 histologically confirmed incidents of breast cancer cases, and 171 age-matched controls with no present, or previous, history of cancer. A PCR method was used for the genotyping analyses, and statistical evaluation was performed by an unconditional logistic regression model. RESULTS: No association was observed in the study subjects, or the premenopausal women group with GSTP1 Val allele. However, postmenopausal women with GSTP1 Val allele had a reduced risk of breast cancer (OR=0.3, 95% CI=0.1~0.7). When the data were stratified, by the known risk factors of breast cancer, a significant interaction was observed between the GSTP1 genotype and alcohol consumption (p for interaction = 0.01); women with GSTP1 Val allele, that drank regularly, had a 3.0-fold increased risk of breast cancer (95% CI=1.1~7.9), whereas women with GSTP1 Val allele, that never drink, had protective effects (OR=0.4, 95% CI=0.2~0.8). CONCLUSION: Our findings suggest that GSTP1 Ile105Val polymorphism influences the individual susceptibility to breast cancer, and that this effect may be modified by alcohol consumption.

A Case-Control Study on Risk Factors of Benign Breast Disorders in Korea / 한국역학회지

PURPOSE: A hospital-based case-control study was conducted to figure out the risk factors for benign breast disorders in Korea. MATERIALS AND METHODS: Histologically confirmed incident cases of benign breast disorders(n=54) were selected from inpatients with life-style information at the Department of General Surgery, Seoul National University Hospital during 1994 to 1997. Women with free of self-reporting past history of any malignancies were regarded as controls who were selected from the inpatients at the same department of the same hospital(n=180). Information on life-styles including reproductive factors were obtained by direct interview using questionnaire. Adjusted odds ratios and 95% confidence intervals were estimated by multivariate logistic regression model with matching variables. RESULTS: Overall, higher educational level, family history of breast cancer, alcohol drinking, and older age at first fullterm pregnancy related to the risk of benign breast disorders. For premenopausal women, older age, higher educational level, and family history of breast cancer increased the risk of benign breast disorders. For postmenopausal women, alcohol drinking, older age at first fullterm pregnancy, and more frequent experiences of fullterm pregnancy increased the risk. Elder age in postmenopausal women and the experience of breast feeding had, however, protective effect against benign breast disorders. CONCLUSIONS: Although the risk factors for benign breast disease may differ from those for breast cancer, these findings are consistent with the hypothesis of excessive circulating estrogen. The present data indicate some risk factors of benign breast disorders are confirmed as risk factors for breast cancer though a substantial agreement between the risk factors for (pathologically confirmed) benign and malignant breast disease.

Glutathione S-transferase(GST) M1 and T1 Genetic Polymorphism in Benign Breast Disorders of Korean Women / 한국역학회지

PURPOSE: A hospital-based case-control study was conducted to evaluate the role of glutathione-S-transferase(GST)M1 and GSTT1 genetic polymorphism for developing benign breast disorders(fibrocystic diseases and fibroadenoma) in Korea. MATERIALS AND METHODS: Histologically confirmed incident cases of benign breast disorder(n=56) were selected from inpatients at the Department of General Surgery, Seoul National University Hospital since 1994. Women with free of self-reporting past history of any malignancies were regarded as controls who were selected from the inpatients at the same department at three hospitals during 1994 to 1998(n=180). Information on life-styles including reproductive factors were obtained by direct interview using questionnaire. Age and menopausal status were matched and 51 cases and 102 controls were finally selected. Odds ratio and 95% confidence interval were estimated by multiple logistic regression after adjusting for age, education, body mass index, smoking history, drinking history, menstrual regularity, age at menarch, age at first pregnancy, frequency of fullterm pregnancy, breast feeding history, duration of breast feeding, and family history of breast cancer. RESULTS: GSTM1-null type showed no significance related to the risk of benign breast disorder(adjusted OR=0.8, 95% CI=0.38-1.83) and GSTT1-null type was also not significant(adjusted OR=1.4, 95% CI=0.63-3.29). Increasing tendency of disease risk by the number of GSTs null type was not observed (ptrend>0.1) after adjusting for all other variables. DISCUSSIONS: Further investigation with larger sample size should be needed to provide more concrete information on the role of GST genetic polymorphism in benign breast cancer and a lots of studies relation in normal level of GST genetic polymorphism in general population should be performed.