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Objectives To develop a convolutional neural network system to jointly segment and classify a hepatic lesion selected by user clicks in ultrasound images. Methods In total, 4309 anonymized ultrasound images of 3873 patients with hepatic cyst (n = 1214), hemangioma (n = 1220), metastasis (n = 1001), or hepatocellular carcinoma (HCC) (n = 874) were collected and annotated. The images were divided into 3909 training and 400 test images. Our network is composed of one shared encoder and two inference branches used for segmentation and classification and takes the concatenation of an input image and two Euclidean distance maps of foreground and background clicks provided by a user as input. The performance of hepatic lesion segmentation was evaluated based on the Jaccard index (JI), and the performance of classification was based on accuracy, sensitivity, specificity, and the area under the receiver operating characteristic curve (AUROC). Results We achieved performance improvements by jointly conducting segmentation and classification. In the segmentation only system, the mean JI was 68.5%. In the classification only system, the accuracy of classifying four types of hepatic lesions was 79.8%. The mean JI and classification accuracy were 68.5% and 82.2%, respectively, for the proposed joint system. The optimal sensitivity and specificity and the AUROC of classifying benign and malignant hepatic lesions of the joint system were 95.0%, 86.0%, and 0.970, respectively. The respective sensitivity, specificity, and the AUROC for classifying four hepatic lesions of the joint system were 86.7%, 89.7%, and 0.947. Conclusions The proposed joint system exhibited fair performance compared to segmentation only and classification only systems. Key Points • The joint segmentation and classification system using deep learning accurately segmented and classified hepatic lesions selected by user clicks in US examination. • The joint segmentation and classification system for hepatic lesions in US images exhibited higher performance than segmentation only and classification only systems. • The joint segmentation and classification system could assist radiologists with minimal experience in US imaging by characterizing hepatic lesions.

OBJECTIVES: The objective of our study was to evaluate the association between occupational exposure to trichloroethylene (TCE), a suspected lymphomagen, and serum levels of miRNAs in a cross-sectional molecular epidemiology study of TCE exposed workers and comparable unexposed controls in China. METHODS: Serum levels of 40 miRNAs were compared in 74 workers exposed to TCE (median: 12 ppm) and 90 unexposed control workers. Linear regression models were used to test for differences in serum miRNA levels between exposed and unexposed workers and to evaluate exposure-response relationships across TCE exposure categories using a three-level ordinal variable (i.e., unexposed

The objective of this study is to assess human exposure to phthalates and its associations with demographic characteristics of the subjects in the Korean National Human Biomonitoring Survey. The subjects aged between 18 and 69 were selected through nationwide stratified sampling. A total of 1874 urine samples were collected and stored at -20 °C until measurement for ten selected metabolites of phthalates (MnBP, MiBP, MBzP, MCHP, MnOP, MEHP, MEOHP, MEHHP, MiNP, and MiDP) using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The difference in the level of urinary phthalate metabolites by the characteristics of the subjects was tested for statistical significance using SAS Surveyreg procedure. The coefficients and standard errors from multiple linear regressions were exponentiated to estimate the adjusted proportional change (APC) and 95% CIs compared with a referent level. The proportion of data above LOQ was less than 20% for MCHP, MnOP, MiNP, and MiDP. Geometric means of creatinine-adjusted concentrations (unit: μg/g creatinine) of six other phthalate metabolites among Korean adults were 41.7 (95% CI 39.6-43.9) for MnBP, 17.1 (95% CI 16.1-18.1) for MiBP, 15.7 (95% CI 14.4-17.1) for MBzP, 8.65 (95% CI 8.10-9.22) for MEHP, 17.5 (95% CI 16.8-18.3) for MEOHP, and 38.1 (95% CI 36.2-40.2) for MEHHP. Urinary level of phthalates tended to be higher among subjects with older age, females, and those with vigorous daily physical activity and tended to be lower among drinkers and those with higher income. Our results suggest that the level of phthalate exposure is significant among Korean adults and thus warrants further studies to identify major source and route of exposure to phthalates.

The purpose of this study is to evaluate the associations of sleep duration and with metabolic syndrome and its components. A total of 72,673 participants from the Health Examinees Study were analyzed to investigate the association of sleep duration with metabolic syndrome and its components. Using the NCEP-ATP III guideline and multiple logistic regression models, odds ratios (ORs) were estimated, stratified by sex. Long-sleep duration was significantly associated with an increased OR for metabolic syndrome in women (OR 1.53, 95 % CI 1.32–1.78), but not in men (1.19, 0.98–1.46). Both short- and long-sleep duration were significantly associated with elevated triglycerides among men (short and long sleep, respectively: 1.09, 1.00–1.19; 1.26, 1.04–1.52). Women were associated with long-sleep duration and all of metabolic syndrome components, especially triglycerides (1.29, 1.11–1.50). In conclusion, long-sleep duration is significantly associated with metabolic syndrome in women. Moreover, triglycerides revealed association across sleep duration among components of metabolic syndrome.

To describe the study design, methods, and baseline results of a prospective cohort of radiologic technologists which we have initiated in South Korea. The cohort participants were enrolled through a self-administered questionnaire survey administered from April 2012 to May 2013. Survey data were linked with radiation dosimetry, a cancer registry, and health insurance data by personal identification numbers. A nationwide representative survey was also conducted using a stratified random sampling design with face-to-face interviews. A total of 12,387 radiologic technologists were enrolled, which accounted for approximately 63 % of all diagnostic radiologic technologists working in South Korea. For nationwide survey, 585 workers were interviewed using the detailed questionnaire, and buccal cells were also collected by scraping the inside of the cheek. The majority of study subjects were under 50-year-old and male workers. The average annual effective dose of radiation declined both men (from 2.75 to 1.43 mSv) and women (from 1.34 to 0.95 mSv) over the period of 1996–2011. A total of 99 cancers (66 cancers in men and 33 in women) were reported from 1992 to 2010. The standardized incidence ratio of all cancer combined was significantly lower in men (SIR = 0.75, 95 % CI 0.58–0.96) than general population, but the ratios for thyroid cancer were significantly higher than expected among both men and women. This cohort provides comprehensive information on work activities and health status of diagnostic radiologic technologists. In addition, the nationwide representative sample provides unique opportunities compared with previous radiologic technologist studies.

The methylation profiles of nine cancer-associated genes were compared with the percent of methylation ratio (PMR) using quantitative methylation RT-PCR in 16 normal lung tissue samples and 80 non-small cell lung cancer (NSCLC) tissues samples. The methylation of nine cancer-associated genes showed a significant increase in tumors compared to matched normal lung tissues, and the level of gene methylation in NSCLC patients containing both adjacent nontumor and tumor tissues showed a significant increase compared to normal lung tissues (P

A recent genome-wide association study (GWAS) of subjects from Japan and South Korea reported a novel association between the TP63 locus on chromosome 3q28 and risk of lung adenocarcinoma (p = 7.3 × 10(-12)); however, this association did not achieve genome-wide significance (p ≤ 10(-7)) among never-smoking males or females. To determine if this association with lung cancer risk is independent of tobacco use, we genotyped the TP63 SNPs reported by the previous GWAS (rs10937405 and rs4488809) in 3,467 never-smoking female lung cancer cases and 3,787 never-smoking female controls from 10 studies conducted in Taiwan, Mainland China, South Korea, and Singapore. Genetic variation in rs10937405 was associated with risk of lung adenocarcinoma [n = 2,529 cases; p = 7.1 × 10(-8); allelic risk = 0.80, 95% confidence interval (CI) = 0.74-0.87]. There was also evidence of association with squamous cell carcinoma of the lung (n = 302 cases; p = 0.037; allelic risk = 0.82, 95% CI = 0.67-0.99). Our findings provide strong evidence that genetic variation in TP63 is associated with the risk of lung adenocarcinoma among Asian females in the absence of tobacco smoking.

Recent compelling evidence indicates that mutation, aberrant expression, and dysregulation of microRNA (miRNA) biogenesis are implicated in cancer development and progression. Based on the important role of miRNA biogenesis pathway in carcinogenesis, we hypothesized that genetic variations in this pathway genes may play a role as susceptibility factors for breast cancer. To test this hypothesis, we investigated the associations between 41 single nucleotide polymorphisms (SNPs) in 14 genes involved in miRNA biogenesis pathway and breast cancer risk in a case–control study of 559 Korean breast cancer cases and 567 controls frequency-matched by age. In all women, 3 SNPs (AGO1 rs595055, AGO2 rs3864659, and p68 rs1991401) were significantly associated with breast cancer risk. In stratified analysis by menopausal status, altered risk associations were observed for 7 SNPs in postmenopausal breast cancer. When subjects were grouped by the number of high-risk genotypes, we found a progressive increase in gene-dosage effect (P trend = 9.46E−7). The protective effects of AGO2 rs3864659 and HIWI rs11060845 were more pronounced in progesterone receptor-positive (PR+) cancer than in progesterone receptor-negative (PR−) cancer (odds ratio (OR), 0.50; 95% confidence interval (CI), 0.30–0.84 vs. OR, 0.94; 95% CI, 0.60–1.84; P heterogeneity = 0.04 and OR, 0.57; 95% CI, 0.37–0.88 vs. OR, 0.97; 95% CI, 0.65–1.44; P heterogeneity = 0.02, respectively), and the DROSHA rs644236 had stronger association with estrogen receptor-negative (ER−) cancer than for estrogen receptor-positive (ER+) cancer (OR, 1.39; 95% CI, 1.08–1.78 vs. OR, 1.05; 95% CI, 0.85–1.29; P heterogeneity = 0.04). Our results suggest that genetic variants in miRNA biogenesis pathway genes may be associated with breast cancer risk, and the modifiable effects might be different according to the menopausal status and hormone receptor status.

To evaluate the immunosuppressive effects of job stress in female nurses, an 8-month longitudinal study was conducted at a major university hospital. Four groups of ten subjects each were constructed to represent high versus low objective stress and high versus low subjective stress based on their responses to a job stress questionnaire and objective stress ratings of the hospital’s work units. Number of white blood cells (i.e., T cells, B cells, and natural killer cells), and lymphocytic proliferation to mitogens (concanavalin A, phytohemagglutinin, and pokeweed) and toxoid (tetanus) were measured by flow cytometry and radioimmunoassay. Serum levels of hydrocortisol, IL-1β, IFN-γ, and TNF-α, and salivary IgA were measured by enzyme-linked immunosorbent assay. The data were analyzed by repeated measures analysis of variance controlling for age and smoking. The level of white blood cells was lower among high objective stress group (median: 7,170/m3; range: 5,386–10,057) compared with that among low objective stress group (8,063; 5,888–9,875) (P = 0.03), however, no other cellular blood variables were found to be significant. In terms of humoral immuno-biomarkers, the level of TNF-α was moderately lower among high objective stress group (1.7 ng/ml; 0.3–2.7) compared with that among low objective stress group (2.2; 0.5–3.5) (P = 0.07), whereas the level of total sIgA was significantly higher among higher objective stress group (72.9 end-point titer/mg/ml/min; 14.4–153.4) compared with that among low objective stress group (44.8; 9.9–123.8) (P = 0.02). The results of the study suggest that psychological job stress affects the levels of some immunological biomarkers in female nurses.

Domestic fuel combustion from cooking and heating, to which about 3 billion people worldwide are exposed, is associated with increased lung cancer risk. Lung cancer incidence in Xuanwei is the highest in China, and the attributable risk of lung cancer from unvented smoky coal burning is greater than 90%. To evaluate any lung cancer mortality reduction after changing from unvented stoves to portable stoves, we used lifetime smoky coal users in a retrospective cohort of all farmers born during 1917–1951 and residing in Xuanwei in 1976. Of the 42 422 enrolled farmers, 4054 lifetime smoky coal users changed to portable stoves, 4364 did not change, and 1074 died of lung cancer. Lung cancer morality associated with stove change was assessed by product-limit survival curves and multivariate Cox regression models. Both men (P

In this paper, we propose a new stereo matching method using the population-based Markov Chain Monte Carlo (Pop-MCMC), which belongs to the sampling-based methods. Since the previous MCMC methods produce only one sample at a time, only local moves are available. In contrast, the proposed Pop-MCMC uses multiple chains in parallel and produces multiple samples at a time. It thereby enables global moves by exchanging information between samples, which in turn, leads to faster mixing rate. In the view of optimization, it means that we can reach a lower energy state rapidly. In order to apply Pop-MCMC to the stereo matching problem, we design two effective 2-D mutation and crossover moves among multiple chains to explore a high dimensional state space efficiently. The experimental results on real stereo images demonstrate that the proposed algorithm gives much faster convergence rate than conventional sampling-based methods including SA (Simulated Annealing) and SWC (Swendsen-Wang Cuts). And it also gives consistently lower energy solutions than BP (Belief Propagation) in our experiments. In addition, we also analyze the effect of each move in Pop-MCMC and examine the effect of parameters such as temperature and the number of the chains.

This study was conducted to evaluate the potential role of CASP8 genetic polymorphisms in the etiology of breast cancer in a case–control study, Korea. Incident breast cancer cases confirmed histologically (n = 1,599) were recruited from two hospitals in Seoul during 2001–2005. Control subjects (n = 1,536) were selected from the Health Examinee Cohort from Seoul and Gyeonggi Province surrounding Seoul, Korea. Three SNPs (D302H D > H, 5′-UTR C > T, and K337K G > A) were genotyped by the primer extension assay. The CASP8 D302H, which was not polymorphic in 48 samples, was excluded in further genotyping. Odds ratios and 95% confidential intervals (95% CIs) were estimated by unconditional logistic regression model adjusted for age at enrollment, education, age at first full-term pregnancy, cigarette smoking, and family history of breast cancer. The 5′-UTR T allele containing genotypes (CT/TT) were associated with an increased risk of breast cancer, compared with those with the CC genotype (OR = 1.13, 95% CI = 0.95–1.34; and OR = 1.48, 95% CI = 1.04–2.10, respectively; P-trend = 0.02). When stratified by the estrogen and progesterone receptor status, the association between the 5′-UTR T allele and breast cancer risk was prominent in ER(+) and PR(+) cases among pre-menopausal women (OR = 1.31, 95% CI = 1.00–1.72 and OR = 1.40, 95% CI = 1.06–1.85, respectively), whereas the association was found prominent in ER(−) or PR(−) cases (OR = 1.32, 95% CI = 0.93–1.87 and OR = 1.42, 95% CI = 1.04–1.94, respectively) among post-menopausal women. Our results thus suggest that the CASP8 5′-UTR C > T are associated with breast cancer risks and the effect may be modified by estrogen and progesterone receptor status.

Dysregulation of the one-carbon metabolic pathway, which controls nucleotide synthesis and DNA methylation, may promote lymphomagenesis. We evaluated the association between polymorphisms in one-carbon metabolism genes and risk of non-Hodgkin lymphoma (NHL) in a population-based case-control study in Australia. Cases (n = 561) and controls (n = 506) were genotyped for 14 selected single-nucleotide polymorphisms in 10 genes (CBS, FPGS, FTHFD, MTHFR, MTHFS, MTR, SHMT1, SLC19A1, TCN1, and TYMS). We also conducted a meta-analysis of all studies of Caucasian populations investigating the association between MTHFR Ex5+79C > T (a.k.a., 677C>T) and NHL risk. A global test of 13 genotypes was statistically significant for diffuse large B-cell lymphoma (DLBCL; P = 0.008), but not for follicular lymphoma (FL; P = 0.27) or all NHL (P = 0.17). The T allele at MTHFR Ex5+79 was marginally significantly associated with all NHL (OR = 1.25, 95% CI = 0.98–1.59) and DLBCL (1.36, 0.96–1.93). The T allele at TYMS Ex8+157 was associated with a reduced risk of FL (0.64, 0.46–0.91). An elevated risk of NHL was also observed among carriers of the G allele at FTHFD Ex21+31 (all NHL, 1.31, 1.02–1.69; DLBCL, 1.50, 1.05–2.14). A meta-analysis of 11 studies conducted in Caucasian populations of European origin (4,121 cases and 5,358 controls) supported an association between the MTHFR Ex5+79 T allele and increased NHL risk (additive model, P = 0.01). In conclusion, the results of this study suggest that genetic polymorphisms of one-carbon metabolism genes such as MTHFR and TYMS may influence susceptibility to NHL.

Cytochrome P450 1A1 (CYP1A1) is involved in the 2-hydroxylation of estrogen, the hormone that plays a critical role in the etiology of breast carcinoma. We evaluated the associations between two CYP1A1 polymorphisms [MspI (rs4646903); Ile462Val (rs1048943)] and breast cancer in a multicenter case-control study of 513 breast cancer cases and 447 controls in Korea. Women carrying the T allele of the CYP1A1 MspI polymorphism were found to have a 1.72-fold (95% CI 1.11-2.68) greater risk of developing breast cancer. No association was found between any CYP1A1 Ile462Val polymorphism and breast cancer. Haplo - type analysis of the two loci showed that the CA haplotype was associated with the lowest risk of breast cancer, and CA/CA diplotypes were associated with a lower risk of breast cancer [OR = 0.28 (0.13-0.61)] than others/others diplotypes. Moreover, this reduced risk was more pronounced among women with a lower body mass index (BMI) [OR = 0.18 (0.06-0.58)] or with a shorter lifetime exposure to estrogen [OR = 0.23 (0.07-0.81)]. The results obtained suggest that the CYP1A1 MspI polymorphisms could affect susceptibility to breast cancer.

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.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.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.Our results suggest that genetic polymorphisms of interleukin-1 may play a role in the individual susceptibility for breast cancer development 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-β1 T 29C and TNF-β 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-β1 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-β 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 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-β1 and TNF-β genes may modify individual susceptibility to breast cancer in Korean women.

CYP17 gene is involved in steroidogenesis and steroid metabolism. Epidemiologic results on the association between the CYP17 polymorphism and breast cancer risk have been inconsistent. We exam ined the association between the MspAI polymorphism at +27 relative to the start of transcription in the 5’-untranslated region of CYP17 gene and breast cancer risk in Korean women. Four hundred and sixty-two incident cases and 337 controls were recruited from three teaching hospitals in Seoul during 1994-2001. Polymorphism of the CYP17 gene was determined by a single base extension assay. Demographic and lifestyle characteristics were identified using structured questionnaire. Age-adjusted (aOR) and multivariate odds ratios (mOR) and 95% confidence intervals (CI) were estimated by unconditional logistic regression. The proportions of A1/A1, A1/A2 and A2/A2 genotypes among controls were 20.8%, 45.1% and 34.1%, respectively. Compared to the A1/A1 genotype, A1/A2 or A2/A2 genotype was not statis tically significantly assoc ia ted with overa ll breast cancer risk (i.e., mOR = 1.01, 95% CI = 0.69-1.47 and mOR = 0.76, 95% CI = 0.51-1.14, respectively). However, a significant association between CYP17 A2/A2 genotype and breast cancer was observed am ong women aged 50 years or less (mOR = 0.58, 95% CI = 0.34-0.99, P =0.04) and leaner women (body mass index ＜ 22 ㎏/ ㎡) (mOR = 0.48, 95% CI = 0.23-0.97, P = 0.04). Our results suggest that genetic polymorphism in 5’-untranslated region of CYP17 might play a role in breast cancer development in Korean women among younger women aged less than 50 or leaner women with body mass index less than 22 ㎏/㎡.

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 (Por = 0.01), but not in postmenopausal women (P0.05). 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 (P0.01). Our findings suggest that genetic polymorphisms GSTM1/T1 could modify estrogen-related breast cancer risk.

Background Although a number of experimental studies have suggested the role of lipocalin-2 (LCN2) and matrix metalloproteinase-9 (MMP-9) in breast cancer progression, limited numbers of epidemiological studies have examined the relationship between the levels of lipocalin-2 and MMP-9 and breast cancer survival. Methods Preoperative serum levels of lipocalin-2 and MMP-9 were measured in 303 breast cancer patients and 74 healthy controls recruited between 2004 and 2007. We examined the association between lipocalin-2 and MMP-9 levels and disease-free survival (DFS) using Cox proportional hazard regression model. Results The serum levels of lipocalin-2 and MMP-9 were not significantly different between patients and controls (P > 0.05). Elevated lipocalin-2 and MMP-9 levels were associated with reduced DFS of breast cancer ( P trend = 0.029 and P trend = 0.063, respectively). When lipocalin-2 and MMP-9 levels were categorized based on the combined risk score, patients with higher levels of both lipocalin-2 and MMP-9 exhibited poor DFS compared to patients with lower levels (P trend = 0.004). Furthermore, these effects were profound in patients with BMI less than 25 kg/m2 (adjusted hazard ratio (aHR), 3.17; 95% confidence intervals (CI), 1.66-6.06, P trend P trend Conclusions Our study suggests that the elevated levels of lipocalin-2 and MMP-9 are associated with reduced breast cancer survival, particularly in patients with lower BMI and lymph-node negative breast cancers.

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).