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Background and Objectives: Sleep duration has been associated with cardiometabolic risk and mortality. The health-related quality of life represents a patient's comprehensive perception of health and is accepted as a health outcome. We examined the relationship between sleep duration and health-related quality of life in predialysis CKD., Design, Setting, Participants, & Measurements: In this cross-sectional study, data from 1910 adults with CKD enrolled in the Korean Cohort Study for Outcome in Patients with CKD were analyzed. Health-related quality of life was assessed with the physical component summary and mental component summary of the Short Form-36 Health Survey. Low health-related quality of life was defined as a Short Form-36 Health Survey score >1 SD below the mean. Using a generalized additive model and multivariable logistic regression analysis, the relationship between self-reported sleep duration and health-related quality of life was examined., Results: Seven-hour sleepers showed the highest health-related quality of life. We found an inverted U-shaped relationship between sleep duration and health-related quality of life as analyzed by a generalized additive model. In multivariable logistic analysis, short sleepers (≤5 h/d) had lower health-related quality of life (odds ratio, 3.23; 95% confidence interval, 1.86 to 5.60 for the physical component summary; odds ratio, 2.37; 95% confidence interval, 1.43 to 3.94 for the mental component summary), and long sleepers (≥9 h/d) had lower health-related quality of life (odds ratio, 2.80; 95% confidence interval, 1.55 to 5.03 for the physical component summary; odds ratio, 2.08; 95% confidence interval, 1.20 to 3.60 for the mental component summary) compared with 7-hour sleepers. Sleep duration had a significant U-shaped association with low health-related quality of life., Conclusions: These findings suggest that short or long sleep duration is independently associated with low health-related quality of life in adults with CKD., (Copyright © 2018 by the American Society of Nephrology.)

A locus at 19p13 is associated with breast cancer (BC) and ovarian cancer (OC) risk. Here we analyse 438 SNPs in this region in 46,451 BC and 15,438 OC cases, 15,252 BRCA1 mutation carriers and 73,444 controls and identify 13 candidate causal SNPs associated with serous OC (P=9.2 × 10(-20)), ER-negative BC (P=1.1 × 10(-13)), BRCA1-associated BC (P=7.7 × 10(-16)) and triple negative BC (P-diff=2 × 10(-5)). Genotype-gene expression associations are identified for candidate target genes ANKLE1 (P=2 × 10(-3)) and ABHD8 (P<2 × 10(-3)). Chromosome conformation capture identifies interactions between four candidate SNPs and ABHD8, and luciferase assays indicate six risk alleles increased transactivation of the ADHD8 promoter. Targeted deletion of a region containing risk SNP rs56069439 in a putative enhancer induces ANKLE1 downregulation; and mRNA stability assays indicate functional effects for an ANKLE1 3'-UTR SNP. Altogether, these data suggest that multiple SNPs at 19p13 regulate ABHD8 and perhaps ANKLE1 expression, and indicate common mechanisms underlying breast and ovarian cancer risk.

Patients often have preconceived notions about acne treatments before visiting dermatologists. The aim of this study was to explore the association between patients' beliefs regarding acne and physicians' suggestion for treatment modality in dermatology clinics. A cross-sectional, nationwide multicentre study was conducted. A total of 1,370 patients completed questionnaires about beliefs about acne treatment before seeking medical care, and 101 dermatologists assessed their acne severity and proposed treatment methods. We found that patients had preconceptions in understanding disease characteristics, assessing subjective acne severity and preferring specific treatment modalities. Dermatologists' determination of topical agents as first-line treatment was affected by disease severity and patients' preferences. They were also more likely to prescribe isotretinoin even in moderate acne compared to oral antibiotics and topical agents. Selections of physical treatments and light-based therapies were affected by patients' preferences, subjective self-evaluation and dermatologists' assessments. Thus, we suggest that acne treatment strategies should incorporate both patients' subjective perceptions and objective clinical practices into a management paradigm.

Background: To determine the accuracy of several preoperative tests in predicting lymph node (LN) metastases and the feasibility of doing a routine lymphadenectomy in clinical stage-I endometrial cancer., Material/methods: We reviewed 132 patients with clinical stage-I endometrial cancer. The preoperative tests used to predict LN metastases were serum CA-125 level, histologic type and grade, LN status assessed by pelvic magnetic resonance image (MRI) or computed tomography (CT), and depth of myometrial invasion assessed only by pelvic MRI. The cutoff value of the serum CA-125 level was determined using receiver operating characteristic curves. Multivariate logistic regression analyses were used to determine which tests are good predictors of LN metastases., Results: Of 132 patients, 13 (9.8%) had LN metastases. On univariate logistic regression analysis, a high CA-125 level and preoperative LN evaluation by pelvic MRI or CT were significant predictors for LN metastases (OR=17.41, 95% CI: 4.36-69.56 and OR=14.30, 95% CI: 4.02-50.63, respectively). However, on multivariate logistic regression analysis adjusted for age and all preoperative tests, a high CA-125 level was the most significant predictor (OR=13.73, 95% CI: 2.03-92.73). Among the 97 patients with no significant predictor of LN metastases, pelvic LN metastases were observed in 3 patients (3.1%) and para-aortic LN metastases were observed in 1 patient (1.1%). Surgical complications were mild (lymphocele, n=9; lymphedema, n=2; wound problem, n=2)., Conclusions: Considering the importance of LN metastases as an indicator of prognosis, and the relatively low surgical risk of lymphadenectomy, clinicians should cautiously consider routine lymphadenectomy in patients with clinical stage-I endometrial cancer.

To evaluate the relationship of genetic polymorphism in XRCC3 Thr(241)Met and the risk of breast cancer, a hospital-based case-control study was conducted in Korea. Histologically confirmed breast cancer cases (n = 574) and controls (n = 502) with no present or previous history of cancer were recruited from several teaching hospitals in Seoul during 1995-2001. Information on demographic characteristics and other information were collected by interviewed questionnaire. Genetic polymorphisms of XRCC3 Thr(241)Met (C > T) was determined by single base extention assay. The frequency of Thr/Thr, Thr/Met, and Met/Met genotype were 89.4, 10.4, 0.2% in cases and 92.3, 7.7, 0.0% in controls, respectively. Genotype distribution in controls fit well to the Hardy-Weinberg equilibrium (P = 0.74). XRCC3 codon 241 Thr/Met or Met/Met genotype moderately increased the risk of breast cancer (OR = 1.4, 95% CI: 0.87-2.33), but not significant in this study. In the results of meta-analysis using twelve reports, however, Thr/Met or Met/Met genotype increased the risk of breast cancer (OR = 1.08, 95%CI: 1.00-1.17). In conclusion, although the genetic polymorphism of XRCC3 Thr(241)Met was unlikely to have a substantial overall association in Korean women, the meta-analysis of studies, including ours, provided that Thr/Met and Met/Met was weakly increased the risk of breast cancer compare to Thr/Thr genotype.

Lactation might have a crucial role in an extraordinary increase in breast cancer incidence in Korea, as the proportion of mothers who practised breast-feeding fell dramatically. This hospital-based case-control analysis has been carried out since 1997 to evaluate whether lactation is associated with breast cancer risk in Korean women. Among the eligible study participants, a total of 753 histologically confirmed incident cases and an equal number of controls were included in the analysis. The risk was estimated using unconditional logistic regression models. Family history, older at menopause, more full-term pregnancies increased the risk of breast cancer. Breast cancer risk decreased according to the total months of breast-feeding (P for trend=0.03). Average duration of breast-feeding of 11-12 months reduced risk of breast cancer by 54% compared with the duration of 1-4 months (odds ratio, 0.46; 95% confidence interval, 0.30-0.70). The decreasing risk trend according to average months of breast-feeding was also statistically significant (P for trend=0.02). Moreover, a reduced risk of breast cancer was apparent when analysis was restricted to the first breast-fed child (P for trend=0.006). This study confirms that lactation has an apparent dose-dependent protective effect against breast cancer in Korean women.

High estrogen exposure in utero may increase breast cancer risk later in life. However, studies of the associations between perinatal factors presumed to affect the fetal hormonal environment and breast cancer risk are inconsistent. We used data from a population-based case-control study of 2,386 incident breast cancers and 2,502 controls in Poland to evaluate risks associated with various perinatal characteristics. After adjusting for confounders, we found a significant trend (p = 0.01) of breast cancer risk with birth weight (OR = 1.54, 95% CI 1.08-2.19 for birth weights >4,000 g vs. <2,500 g). Subjects with a high birth order (> or =6) were at reduced risk (OR = 0.81, 0.61-1.06) when compared with first born subjects. Birth weight was somewhat a stronger risk predictor among subjects whose cancers were diagnosed at 50 years of age or older (OR = 1.84, 1.19-2.85) than among those with cancers diagnosed at younger ages (OR = 1.14, 0.61-2.12). Subjects whose mothers smoked during their pregnancies were at slightly higher risk than those who never smoked (OR = 1.21, 0.99-1.47), but the risk was similar to mothers who only smoked at other times (OR = 1.22, 0.81-1.84). Breast cancer risk was not related to paternal smoking, maternal age, gestational age or twin status. Our results add support to the growing evidence that some perinatal exposures may relate to breast cancer risk. Additional studies are needed to confirm associations and clarify the biologic mechanisms underlying these associations.

Objectives: Diabetes has been reported as a risk factor for several cancers. However, the association between diabetes and gastric cancer has been inconsistent. The aim of this study was to evaluate the association between the fasting serum glucose level and gastric cancer risk in Korea., Methods: Among the members of the Korean MultiCenter Cancer Cohort (KMCC) from 1993 to 2004, a total of 100 incident gastric cancer cases were ascertained until December 31, 2002 and 400 controls were matched according to age, sex, and year and area of enrollment. Of the eligible subjects, those without fasting serum glucose level information were excluded, with a total of 64 cases and 236 controls finally selected. On enrollment, all subjects completed a baseline demographic and lifestyle characteristics questionnaire, and had their fasting serum glucose level measured. The Helicobacter pylori infection status was determined by an immunoblot assay using long-term stored serum. The odds ratios (ORs) were estimated using conditional and unconditional logistic regression models adjusted for the H. pylori infection status, smoking, drinking, education, follow-up period and matching variables., Results: The ORs for risk of gastric cancer according to the serum glucose level were 1.33 [95% CI=0.50-3.53] and 1.66 [95% CI=0.55-5.02] for the categories of 100-125 and 126 mg/dL or greater, respectively, compared to the category of less than 100 mg/dL. No increased risk of gastric cancer according to the serum glucose level was found (p-trend=0.337)., Conclusions: This study provides no evidence for an association of the serum glucose level with gastric cancer.

To evaluate the role of the genetic polymorphisms of CYP2E1, GSTM1 and GSTT1, and their interaction with smoking in lung cancer development in Korean males, a hospital-based case-control study was conducted. Histologically confirmed male lung cancer patients (n=171) and male patients with no present or previous history of systemic illness who visited the urology department (n=196) were recruited from Seoul National University Hospital, Korea (1998-1999). CYP2E1 genotypes were determined by PCR-RFLP using RsaI digestion and GSTM1 and T1 genotypes were determined by multiplex PCR. Risks were estimated as odds ratios (ORs) and 95% confidence intervals (CIs) using a logistic regression model adjusting for age and pack-year. Smoking was a significant risk factor for lung cancer (P<0.001). Although genetic polymorphisms of CYP2E1, GSTM1 and T1 were not associated with the overall risk of lung cancer, the GSTM1 null genotype significantly increased the risk of squamous cell lung cancer (OR=1.9, 95% CI=1.04-3.60). An interactive effect between the GSTM1 null genotype and smoking was observed (P=0.04). These results suggest that the GSTM1 null genotype is associated with squamous cell lung cancer and modifies the effect of smoking on squamous cell lung cancer development in Korean males.

Not only the incidence but the mortality of breast cancer has been steadily increasing in Korea over the last twenty years, and it became the most common female neoplasm in 2002. In fact, the increase in the rate of breast cancer mortality in Korea over the past 10 years has been higher than anywhere else in the world, and it is particularly noteworthy that more than half of the incident cases occur among those younger than 50 years of age. The rapid westernization of dietary habits and changes in reproductive behavior of Korean women presumably played a central role in this extraordinary increase in breast cancer occurrence. A large-scale multi-center case-control analysis showed that an older age, a family history of breast cancer, early menarche, late menopause, late full-term pregnancy, never-having had a breast-fed child, and postmenopausal obesity are breast cancer risk factors in Korea. Environmental and genetic factors are known to play interactive roles in human carcinogenesis and recent studies have shown that genetic polymorphisms may predispose individuals to breast cancer via gene-to-environment or gene-to-gene interactions. Thus research into genetic variation in xenobiotic metabolism, estrogen metabolism, DNA repair, cytokine metabolism, or cell cycle control may give insights into both the etiology and prevention of breast cancer. Epidemiologic evidence obtained from migrant and lifestyle change studies and investigations of main risk factors strongly suggests that breast cancer will further increase in Korea. Future predictions point to a 2- to 3-fold increase in incidence by 2020. Here, we briefly introduce health education programs and breast cancer campaigns, in the broad context of the Korean National Cancer Control Program.

Background: Prostate cancer incidence and mortality rates in South Korea are relatively low, but rising steadily., Methods: We examined age-standardized incidence and mortality trends of prostate cancer in South Korea to gain further insight into prostate cancer etiology., Results: Although prostate cancer incidence has been low (7.9 per 100,000 man-years), it has increased up to 28.2% between 1996-1998 and 1999-2001. Prostate cancer mortality increased 12.7-fold over a 20-year period. Despite the increase in prostate cancer incidence and mortality rates, marked differences in rates remain for Koreans, Korean Americans, and Caucasian Americans., Conclusions: The rising rates of prostate cancer in South Korea cannot be attributed entirely to PSA screening due to the low PSA screening prevalence; this trend is most likely related to increased westernization among Koreans. Interdisciplinary epidemiological studies incorporating the collection of biological samples are needed to clarify the extent to which lifestyle and genetic factors contribute to the observed racial disparity., (Published 2006 Wiley-Liss, Inc.)

Aim: To conduct a retrospective study to determine the risk factors for development of metaplastic gastritis in Korean population., Methods: The database of 113449 subjects who underwent a gastroscopy for the purpose of a regular check-up at center for health promotion, Samsung medical center during 5 years was collected and retrospectively analyzed. Among them, 5847 subjects who had endoscopically diagnosed as a metaplastic gastritis or 10076 normal as well as answered to questionnaire were included for present study. The subjects were divided into 2 groups; Group I, normal and Group II, metaplastic gastritis. Age, gender, Helicobacter pylori (H pylori) seropositivity, body mass index (BMI), family history of cancer, smoking, alcohol consumption, total daily calories, folate and salt intake and dietary habit (out-eating, overeating, irregular eating) were retrieved from questionnaire or electronic medical record and compared between group I and group II., Results: The prevalence of group II was 11% (13578/113449) increasing its prevalence with age (P = 0.000). But, there was no significant association between 2 groups in BMI, family history of cancer, alcohol consumption, total daily calories, folate and salt intake and dietary habit (out-eating, overeating, irregular eating). Old age (P=0.000), male gender (P = 0.000), H pylori seropositivity (P = 0.010) and current smoker (P = 0.000) were significantly more common in group II at multiple logistic regression model., Conclusion: Our data suggested that old age, male gender, H pylori seropositivity and smoking were risk factors for metaplastic gastritis, precancerous lesion of gastric cancer.

Objective: To evaluate the potential role of genetic polymorphisms of interleukin-1 beta (IL-1B) and IL-1 receptor antagonist (IL-1RN) on breast cancer development, a hospital-based case-control study was conducted in Korea., Methods: Histologically confirmed breast cancer cases (n = 560) and controls (n = 509) without cancer history were recruited from three teaching hospitals in Seoul between September 1998 and January 2002. Information on risk factors of breast cancer were collected by interviewed questionnaire. Genotypes of IL-1B (-31C/T) and IL-1RN (86 bp variable number tandom repeats in intron 2) were determined by PCR-CTPP (confronting two-pair primers) and PCR, respectively. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by unconditional logistic regression model., Results: The IL-1RN *2-allele was associated with decreased breast cancer risk with marginal significance (OR = 0.7, 95% CI = 0.48-1.05). The IL-1B CC or TC genotype was not associated with decreased risk of breast cancer (OR = 0.9, 95% CI = 0.65-1.16). However, combination of IL-1B C-allele (CT or CC) and IL-1RN *2-allele containing genotypes significantly decreased the risk of breast cancer (OR = 0.6, 95% CI = 0.39-0.99). A moderately decreasing trend of risk was observed as the number of 'putative low risk' allele increased (p for trend = 0.07). Suggestive combined effect on breast cancer risk was also observed between body mass index (BMI) and IL-1RN non-*2 allele: women with higher BMI and IL-1RN non-*2 allele had 1.7-fold higher risk than women with lower BMI and IL-1RN*2 genotypes., Conclusion: Our results suggest that genetic polymorphisms of interleukin-1 may play a role in the individual susceptibility for breast cancer development in Korean women.

Background: Although breast cancer in women remains relatively rare in Korea, its incidence and mortality figures are increasing, consistent with the increasing risk observed in successive generations of Korean women. The aim of the current study was to examine time trends of breast-cancer mortality during the period 1984-2003 in Korea, assessing the importance of the effects of age, period and birth cohort as risk factors., Methods: Data on the annual number of deaths due to female breast cancer and on female population statistics from 1984 to 2003 were obtained from the Korean National Statistical Office. A log-linear Poisson age-period-cohort model was used to estimate age, period and cohort effects., Results: The trend of breast cancer mortality was explained by an age-cohort model based on goodness of fit, even though the significance of the cohort effect was marginal (p=0.08) after adjusting for age. The risk of breast cancer death was found to increase with age after adjusting for the cohort effect, and it was different from the cross-sectional age curve. Also, breast cancer mortality increased along with the birth cohort., Conclusions: Even though the cohort effect was found to have a marginally significant effect on breast cancer mortality, it is expected to be more significant in the future given the recent on-going changes in diet and reproductive behavior shown by Korean women.

To evaluate the role of genetic polymorphisms of ataxia telangiectasia mutated (ATM) in the etiology of breast cancer, a hospital-based case-control study was conducted in Korea. Nine-hundred ninety-six histologically confirmed incident breast cancer cases and 1,181 cancer-free controls were recruited in Seoul between 1995 and 2003. Genotypes of the ATM polymorphisms-5144A > T, IVS21 + 1049T > C, IVS33 - 55T > C, IVS34 + 60G > A, and 3393T > G were determined by the 5'-nuclease assay. Individual haplotypes were estimated from genotype data by a Bayesian method. Five ATM alleles were found to be in strong linkage disequilibrium (D' > 0.82; P < 0.001). Haplotype frequencies were significantly different between cases and controls (chi2 test, P < 0.001). The ATM IVS21 + 1049 TC or CC, IVS34 + 60 GA or AA, and 3393 TG or GG genotypes were associated with increased breast cancer risk, particularly in premenopausal women [odds ratios (OR), 1.51; 95% confidence interval (CI), 1.11-2.05; OR, 1.42; 95% CI, 1.08-1.88; and OR, 1.37; 95% CI, 1.04-1.80, respectively]. Compared with diploid of TCCAG:TCCAG, the most common haplotype, the ATTGT:ATTGT was associated with decreased risk of breast cancer with borderline significance (OR, 0.77; 95% CI, 0.58-1.04) and TCCAG:ATCGT and ATTGT:ACCAG were associated with increased breast cancer risk (OR, 2.30; 95% CI, 1.18-4.48 and OR, 2.43; 95% CI, 1.1.07-5.52, respectively) after adjusting for age, education, age at first full-term pregnancy, parity, family history of breast cancer, alcohol consumption, and smoking. As the number of ATTGT haplotype decreased, the risk of breast cancer increased (P for trend < 0.01). Our results thus suggest that genetic polymorphisms of ATM play an important role in the development of breast cancer in Korean women.

Objective: The proliferation of malignant breast epithelial cells is regulated by various stimuli including cytokines and growth factors, thus the variants of those genes may modify the breast cancer risk. To evaluate the potential influences of TGF-beta1 T29C and TNF-beta A252G gene polymorphisms on breast cancer risk, a case-control study was conducted in Korea., Methods: Histologically confirmed breast cancer cases (n=560) and controls (n=509) with no previous history of cancer were recruited from three teaching hospitals in Seoul, Korea. Genotypes were determined by PCR-CTPP (polymerase chain reaction with confronting two-pair primers) method. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by unconditional logistic regression model adjusting for age, body mass index, education, parity, age at first full-term pregnancy, and family history of breast cancer., Results: The TGF-beta1 29C-allele containing genotypes posed an increased risk of breast cancer (OR=1.3, 95% CI=1.02-1.79), especially in postmenopausal women (OR=1.6, 95% CI=1.01-2.44). Similarly, the TNF-beta 252G-allele containing genotypes posed an increased risk of postmenopausal breast cancer (OR=1.7, 95% CI=1.09-2.55). The risk of postmenopausal breast cancer increased in parallel with the number of the risk genotypes (p for trend <0.01). When data were stratified by the presumed non-genetic risk factors, TGF-beta1 C-allele containing genotypes were found to increase breast cancer risk almost two-fold in postmenopausal women with greater than median body mass index (>22.8 kg/m2) (OR=1.9, 95% CI=1.04-3.37)., Conclusion: The results of this study therefore suggest that polymorphisms of TGF-beta1 and TNF-beta genes may modify individual susceptibility to breast cancer in Korean women.

Objectives: The purpose of this study was to investigate the effect of genetic polymorphism of cytochrome P450 2E1 (CYP2E1) and aldehyde dehydrogenase 2 (ALDH2) on the xylene metabolism., Methods: Among 247 workers, 116 were occupationally exposed to xylene and 131 were not. Workers exposed to xylene had different work such as spray, touch-up, mix & assist, and pre-treat. Questionnaire variables were age, sex, use of personal protective equipment, smoking, previous night's drinking and work duration. The urinary methylhippuric acid was measured in the urine collected in the afternoon and corrected by urinary creatinine concentration. The genotypes of CYP2E1 and ALDH2 were investigated by using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) methods with DNA extracted from venous blood., Results: 1. The urinary concentrations of o-, m-, and pmethylhippuric acid and total methylhippuric acid in the exposed group were significantly higher than those in the non-exposed group (p&lt; 0.001). 2. In multiple regression analysis, the urinary methylhippuric acid concentration was significantly influenced by exposure grade (Job-exposure matrixes), smoking, drug use and kind of protective equipment (p&lt; 0.1). 3. Genetic polymorphism of CYP2E1 and ALDH2 did not affect urinary methylhippuric acid level in the exposed group (p&gt; 0.05)., Conclusions: Exposure grade, smoking, drug use and kind of protective equipment affected urinary methylhippuric acid level, whereas genetic polymorphism of CYP2E1 and ALDH2 did not. However, further investigation for the effect of genetic polymorphism on the metabolism of xylene with a larger sample size is needed.

Our previous studies suggested that both catechol O-methyl transferase (COMT) and glutathione S-transferase (GST) M1 and T1 genotypes are associated with breast cancer risk. Here we extended the studies to evaluate the potential combined effect of these genotypes in individual breast cancer risk. Incident breast cancer cases (n = 202) and controls (n = 299) with no previous cancer were recruited from three teaching hospitals in Seoul in 1996-1999. Information on putative risk factors was collected by interviewed questionnaire. PCR-based methods were used for the genotyping analyses. Odds ratios (ORs) and 95% confidence (CIs) intervals were estimated by unconditional logistic regression after adjustment for known or suspected risk factors of breast cancer. Among pre-menopausal women the low activity associated (COMT *L) allele containing genotypes and the GSTM1 null genotype posed increased risks of breast cancer with ORs of 1.7 (95% CI = 1.0 - 2.8) and 1.7 (95% CI = 1.0-2.8), respectively. A marginally significant effect of GSTT1 null genotype was also observed when the total study population was considered (OR = 1.3, 95% CI = 1.0-2.1). When the combined genotype effects were examined, the concurrent lack of GSTM1 and GSTT1 genes posed a more than 2-fold risk of breast cancer (OR = 2.2, 95% CI = 1.2-3.9); this effect was mainly attributable in pre-menopausal women (OR = 3.2, 95% CI = 1.5-7.2). Moreover, the breast cancer risk increased in parallel with the number of COMT , GSTM1 , and GSTT1 at-risk genotypes (p for trend = 0.003). This association was particularly clear in pre-menopausal women among whom combination of all three high-risk genotypes posed a 4.1-fold breast cancer risk (95% CI = 1.4-12.7) compared with pre-menopausal women without at-risk genotypes (p for trend = 0.001). The trend was more pronounced in women with BMI greater than 22 kg/m2 (p for trend < 0.001) and high-risk status of parity factor (nulliparous or women with the first full term pregnancy at age of over 25-year-old) (p for trend = 0.013). These results suggest the combined effect between reproductive factors and GSTM1, GSTT1 and COMT genotypes in human breast carcinogenesis.

To evaluate the potential association between the GSTP1 genotype and the development of breast cancer, a hospital based case-control study was conducted on Korean women. The study population consisted of 171 histologically confirmed incident breast cancer cases and 171 age-matched controls with no present or previous history of cancer. PCR-RFLP was used for the GSTP1 genotyping and statistical evaluations were performed using an unconditional logistic regression model. Postmenopausal women with the GSTP1 Val allele were found to have a reduced risk of breast cancer (OR = 0.3, 95 % CI = 0.10-0.74). A significant interaction was observed between the GSTP1 genotype and alcohol consumption (p for interaction = 0.01); compared with never-drinking women with Ile/Ile genotype, ever-drinking women with the GSTP1 Val allele had almost a three-fold risk of breast cancer (OR = 2.9, 95 % CI = 1.05-7.85), whereas never-drinking women with Val allele had half this risk (OR = 0.5, 95 % CI = 0.27-0.93). Our findings suggest that the GSTP1 polymorphism influences individual susceptibility to breast cancer in the Korean women and this effect may be modified by alcohol consumption.

Objectives: Public health concern about the health effects of radio-frequency electromagnetic fields (RF-EMFs) has increased with the increase in public exposure. This study was to evaluate some health effect of RF exposure by the AM radio broadcasting towers in Korea., Methods: We calculated cancer mortality rates using Korean death certificates over the period of 1994-1995 and population census data in ten RF-exposed areas, defined as regions that included AM radio broadcasting towers of over 100 kW, and in control areas, defined as regions without a radio broadcasting tower inside and at least 2 km away from the towers., Results: All cancers-mortality was significantly higher in the exposed areas [direct standardized mortality rate ratio (MRR) = 1.29, 95%CI = 1.12-1.49]. When grouped by each exposed area and by electrical power, MRRs for two sites of 100 kW, one site of 250 kW and one site of 500 kW, for all subjects, and for one site of 100 kW and two sites of 250 kW, for male subjects, showed statistically significant increases without increasing trends according to the groups of electric power. Leukemia mortality was higher in exposed areas (MRR = 1.70, 95% CI = 0.84-3.45), especially among young adults aged under 30 years (0-14 years age group, MRR = 2.29, 95% CI = 1.05-5.98; 15-29 age group, MRR = 2.44, 95% CI = 1.07-5.24)., Conclusions: We observed higher mortality rates for all cancers and leukemia in some age groups in the area near the AM radio broadcasting towers. Although these findings do not prove a causal link between cancer and RF exposure from AM radio broadcasting towers, it does suggest that further analytical studies on this topic are needed in Korea.

To estimate the prevalence and the related risk factors of low bone mineral density of the calcaneus and the distal radius, a community-based study was conducted in three rural areas of Korea. A total of 1420 women and 732 men aged 40 years and older participated in this study. Information on sociodemographic characteristics and the potential risk factors for osteoporosis were collected by an interviewer-administered standardized questionnaire. Bone mineral density (BMD) of the calcaneus and the distal radius were measured by dual-energy X-ray absorptiometry (DXA). Three hundred and seventeen women and 183 men aged 20-29 years who participated in a regular health check-up were used as a reference population. Osteoporosis was defined using WHO criteria. Odds ratios of the risk factors of osteoporosis were calculated by the unconditional logistic regression model. The standardized prevalence of osteoporosis of the calcaneus was 8.4% for males and 27.3% for females using the Korean population of year 2000 as a standard population. The standardized prevalence of osteoporosis of the distal radius was 4.2% for males and 18.8% for females. Older age and lower body mass index (BMI) were related with low BMD in both the calcaneus and distal radius in males and females. The duration after menopause and the number of live births were an independent risk factor for osteoporosis of the calcaneus (OR = 1.1, 95% CI = 1.00-1.11; the duration after menopause; OR = 2.0, 95% CI = 1.20-3.35, the number of live birth) and a familial history of non-traumatic fractures or osteoporosis among the first-degree relatives was significantly related to a increased risk of osteoporosis of the distal radius in females (OR = 2.9, 95% CI = 1.36-6.31).

We conducted a hospital-based case-control study to evaluate the interactive effect of reproductive factors and glutathione S-transferase (GST) M1 and T1 genetic polymorphisms in individual susceptibility to breast cancer. The study population consisted of 189 incident breast cancer cases and 189 age-matched controls with no known malignant diseases. GSTM1/T1 genotypes were determined by a multiplex polymerase chain reaction (PCR) method, and odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by conditional logistic regression model. The parity factors were grouped as (1) high-risk status defined as nullipara or para with experience of first full-term pregnancy (FFTP) at or over 30 years, and (2) low-risk status defined as para with experience of FFTP under 30 years. A significant multiplicative interaction was observed between GSTM1 and GSTT1 null genotypes and high-risk status of parity factor in all women and in premenopausal women (P < or = 0.01), but not in postmenopausal women (P > 0.05). The interaction between the combined genotypes of GSTM1 and GSTT1 and status of parity factor was also significant in all women and in premenopausal women (P < 0.01). Our findings suggest that genetic polymorphisms GSTM1/T1 could modify estrogen-related breast cancer risk.

The Korean Twin Registry is the first nationwide twin study in Korea. We compiled 154,783 twin pairs from existing nation-wide data sources, mainly from address and national health insurance data. The coverage of this registry was almost complete for the twins born since 1970, but less complete as age increased, so that there were only 990 pairs who were born before 1930. The twins' health examination (N = 54,390 persons) and questionnaire (N = 44,546 persons) results were incorporated into the registry, yielding 12,894 and 9074 concordantly informative pairs. Morbidity and mortality outcomes have been followed up since 1990, for most diseases. For preliminary analysis of complex diseases, we selected ventricular septal defects (VSD) in young twins, stomach and colorectal cancers in adult twins. We identified 353 VSDs, 284 stomach cancers, and 116 colorectal cancers among twins. The prevalence rates of cancers, but not that of VSD, were lower in twins than those in population. The difference in the cancer prevalence was marked for twins born before 1926, implying some degree of selection. Like-sex (LS) twins showed familial recurrence risks (lambdaLS) of 41.2 for VSD and 22.4 for colorectal cancers, and 1.74 for stomach cancers. For opposite-sex (OS) twins, we could estimate lambdaOS of 19.8 for VSD only. These results were compatible with previous studies for VSD and colorectal cancers, but not for stomach cancers. Despite the strength in size, availability of health outcomes, and some lifestyle and basic laboratory data, we need accurate zygosity information to improve the validity of the results.

Cohort studies of human populations have provided the most convincing evidence of links between exposure to specific agents and cancer. The Korean Multi-center Cancer Cohort (KMCC-II) is a multi-center prospective cohort designed to investigate the relationship between exposures to environmental factors, lifestyle factors, host factors and the risk of cancer in Korea. Data on general lifestyle, physical activity, diet, reproductive factors, and agricultural exposures have been collected by direct interview since 1993. Anthropometric measurements and some clinical laboratory findings have also been recorded. This cohort is characterized by the exclusion of cancer cases at the time of recruitment through cancer screening by physicians. The number of cancer-free subjects in the cohort at present totals some 35,692 men and women aged over 35 (121,856 person-years as of December 2000). Of the KMCC-II, 11,045 subjects who have donated their blood and/or urine sample were classified as the KMCC-I. In order to provide an opportunity to incorporate various biomarkers of exposure and the effect of exposure, as well as information on genetic susceptibility, a biological materials bank with blood (plasma, or serum buffy coat, packed erythrocytes) at -70oC and urine supernatants at -20oC has been established for future studies on cancer etiology. The total number of the KMCC-I is 10,694 for the blood bank and 8,907 for the urine bank (total number of observation in person-year = 47,002). Follow-up for cancer incidence has commenced based on an active surveillance system conducted mainly through telephone interview by health personnel or through diagnosis by physicians in each district, and a passive surveillance system through record linkages between the national cancer registry, the national death certificate system, and health insurance medical records databases in Korea. Moreover, this cohort study is expected to play a significant role in assessing the role of genes in the etiology of cancer. These include the determination of the cost-efficiency and reliability of the nested case-control approach, using the cohort, for exploring gene-disease associations and gene-environmental interactions using reduced sample sizes. Along with other cancer cohorts, the KMCC study could eventually provide convincing evidence on new etiologies of cancer in the Asian-Pacific region.