Sleep Duration, Comorbidities, and Mortality in Korean Health Examinees: A Prospective Cohort Study / 예방의학회지

Objectives@#The association between long sleep duration and mortality is frequently attributed to the confounding influence of comorbidities. Nevertheless, past efforts to account for comorbidities have yielded inconsistent outcomes. The objective of this study was to evaluate this relationship using a large prospective cohort in Korea. @*Methods@#The study included 114 205 participants from the Health Examinees Study, who were followed for a median of 9.1 years. A composite comorbidity score was developed to summarize the effects of 21 diseases. Using Cox proportional hazards regression, hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause, cancer, and cardiovascular mortality associated with sleep duration were estimated. These estimates were adjusted for socio-demographic factors, lifestyle factors, body mass index, and comorbidity score. Additionally, a stratified analysis by subgroups with and without comorbidities was conducted. @*Results@#Throughout the follow-up period, 2675 deaths were recorded. After all adjustments, an association was observed between a sleep duration of 8 hours or more and all-cause mortality (HR, 1.10; 95% CI, 1.01 to 1.20). However, no such association was detected in the stratified analysis for the subgroups based on comorbidity status. @*Conclusions@#Long sleep duration was found to be associated with all-cause mortality among Koreans, even after adjusting for comorbidities. Additional studies are required to explore the mechanism underlying the association between sleep duration and major causes of mortality.

Network Analysis in Systems Epidemiology / 예방의학회지

Traditional epidemiological studies have identified a number of risk factors for various diseases using regression-based methods that examine the association between an exposure and an outcome (i.e., one-to-one correspondences). One of the major limitations of this approach is the “black-box” aspect of the analysis, in the sense that this approach cannot fully explain complex relationships such as biological pathways. With high-throughput data in current epidemiology, comprehensive analyses are needed. The network approach can help to integrate multi-omics data, visualize their interactions or relationships, and make inferences in the context of biological mechanisms. This review aims to introduce network analysis for systems epidemiology, its procedures, and how to interpret its findings.

Network Analysis in Systems Epidemiology / 예방의학회지

Traditional epidemiological studies have identified a number of risk factors for various diseases using regression-based methods that examine the association between an exposure and an outcome (i.e., one-to-one correspondences). One of the major limitations of this approach is the “black-box” aspect of the analysis, in the sense that this approach cannot fully explain complex relationships such as biological pathways. With high-throughput data in current epidemiology, comprehensive analyses are needed. The network approach can help to integrate multi-omics data, visualize their interactions or relationships, and make inferences in the context of biological mechanisms. This review aims to introduce network analysis for systems epidemiology, its procedures, and how to interpret its findings.

Adherence to the Recommended Intake of Calcium and Colorectal Cancer Risk in the HEXA Study / Journal of the Korean Cancer Association, 대한암학회지

Purpose@#Dietary calcium intake has been suggested to be protective against the development of colorectal cancer. The mean dietary calcium intake of Koreans is 490 mg/day, which is far below the recommended calcium intake of 700-800 mg/day. In this study, we explored the relationship between dietary calcium intake and colorectal cancer development in Koreans with relatively low calcium intake compared with individuals in Western countries. @*Materials and Methods@#The Health Examinees Study, a large-scale genomic community-based prospective cohort study, was designed to identify the general characteristics of major chronic diseases in Koreans. A total of 119,501 participants aged 40-69 years recruited between 2004 and 2013 were included in this analysis. The calcium intake level was categorized using the Dietary Reference Intakes for Koreans (KDRIs). The Cox proportional hazards regression model was used to estimate the hazard ratio (HR) and the corresponding 95% confidence intervals (CIs) for colorectal cancer risk, adjusting for potential confounders. @*Results@#In the multivariable-adjusted model, compared with the group that consumed less than the recommended amount of calcium, the group that consumed more than the recommended intake of calcium showed a significant reduction in the risk of colorectal cancer in women. (HR, 0.54; 95% CI, 0.31 to 0.95). Among men, however, no significant association was observed between dietary calcium intake and colorectal cancer risk (HR, 0.89; 95% CI, 0.54 to 1.45). @*Conclusion@#Korean women who adhere to the recommended intake of calcium showed a reduced risk of colorectal cancer.

Strong association between herpes simplex virus-1 and chemotherapy-induced oral mucositisin patients with hematologic malignancies

Background/Aims@#A link between oral cavity infections and chemotherapy-induced oral mucositis (CIOM) in patients with hematological malignancies (HMs) undergoing intensive chemotherapy (IC) or hematopoietic stem cell transplantation (HSCT) has been suggested. However, conclusive data are lacking, and there are no current guidelines for the prophylactic use of antimicrobials to prevent CIOM in these populations. @*Methods@#The relationships between herpes simplex virus (HSV) reactivation and Candida colonization in the oral cavity and CIOM in patients with HMs undergoing IC or HSCT were evaluated. Patients aged ≥ 19 years with HMs undergoing IC or HSCT were enrolled. Each patient was evaluated for HSV and Candida in the oral cavity along with CIOM at baseline and during the 2nd, 3rd, and 4th weeks. @*Results@#Seventy presentations among 56 patients were analyzed. CIOM was observed in 23 presentations (32.9%), with a higher incidence associated with HSCT (17 of 35 presentations, 48.6%) than with IC (six of 35 presentations, 8.6%). The reactivation of HSV-1 was significantly associated with an increased incidence of CIOM after adjusting for age, sex, type of disease, and treatment stage. A higher HSV-1 viral load was associated with an increased incidence of CIOM. The presence of Candida was not associated with CIOM. @*Conclusions@#HSV-1 reactivation in the oral cavity was highly associated with CIOM in patients with HMs undergoing high-dose chemotherapy.

Association between Change in Alcohol Consumption and Metabolic Syndrome: Analysis from the Health Examinees Study

BACKGROUND: The association between change in alcohol intake and metabolic syndrome is unclear. METHODS: This retrospective cohort consisted of 41,368 males and females from the Health Examinees-GEM study. Participants were divided into non-drinkers (0.0 g/day), light drinkers (male: 0.1 to 19.9 g/day; female: 0.1 to 9.9 g/day), moderate drinkers (male: 20.0 to 39.9 g/day; female: 10.0 to 19.9 g/day), and heavy drinkers (male: ≥40.0 g/day; female: ≥20.0 g/day) for each of the initial and follow-up health examinations. Logistic regression analysis was used to determine the adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for developing metabolic syndrome according to the change in alcohol consumption between the initial and follow-up health examinations. Adjusted mean values for the change in waist circumference, fasting serum glucose (FSG), blood pressure, triglycerides, and high density lipoprotein cholesterol (HDL-C) levels were determined according to the change in alcohol consumption by linear regression analysis. RESULTS: Compared to persistent light drinkers, those who increased alcohol intake to heavy levels had elevated risk of metabolic syndrome (aOR, 1.45; 95% CI, 1.09 to 1.92). In contrast, heavy drinkers who became light drinkers had reduced risk of metabolic syndrome (aOR, 0.61; 95% CI, 0.44 to 0.84) compared to persistent heavy drinkers. Increased alcohol consumption was associated with elevated adjusted mean values for waist circumference, FSG, blood pressure, triglycerides, and HDL-C levels (all P<0.05). Reduction in alcohol intake was associated with decreased waist circumference, FSG, blood pressure, triglycerides, and HDL-C levels among initial heavy drinkers (all P<0.05). CONCLUSION: Heavy drinkers who reduce alcohol consumption could benefit from reduced risk of metabolic syndrome.

Risk Reduction of Breast Cancer by Childbirth, Breastfeeding, and Their Interaction in Korean Women: Heterogeneous Effects Across Menopausal Status, Hormone Receptor Status, and Pathological Subtypes / 예방의학회지

OBJECTIVES: The purpose of this study was to examine the associations of childbirth, breastfeeding, and their interaction with breast cancer (BC) risk reduction, and to evaluate the heterogeneity in the BC risk reduction effects of these factors by menopause, hormone receptor (HR) status, and pathological subtype. METHODS: BC patients aged 40+ from the Korean Breast Cancer Registry in 2004-2012 and controls from the Health Examinee cohort participants were included in this study after 1:1 matching (12 889 pairs) by age and enrollment year. BC risk according to childbirth, breastfeeding, and their interaction was calculated in logistic regression models using odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: BC risk decreased with childbirth (3+ childbirths relative to 1 childbirth: OR, 0.66; 95% CI, 0.56 to 0.78 and OR, 0.80; 95% CI, 0.68 to 0.95 in postmenopausal and premenopausal women, respectively); and the degree of risk reduction by the number of children was heterogeneous according to menopausal status (p-heterogeneity=0.04), HR status (p-heterogeneity < 0.001), and pathological subtype (p-heterogeneity < 0.001); whereas breastfeeding for 1-12 months showed a heterogeneous association with BC risk according to menopausal status, with risk reduction only in premenopausal women (p-heterogeneity < 0.05). The combination of 2 more childbirths and breastfeeding for ≥13 months had a much stronger BC risk reduction of 49% (OR, 0.51; 95% CI, 0.45 to 0.58). CONCLUSIONS: This study suggests that the combination of longer breastfeeding and more childbirths reduces BC risk more strongly, and that women who experience both 2 or more childbirths and breastfeed for ≥13 months can reduce their BC risk by about 50%.

Genetic Predisposition of Polymorphisms in HMGB1-Related Genes to Breast Cancer Prognosis in Korean Women / 한국유방암학회지

PURPOSE: The high mobility group box 1 (HMGB1) protein has roles in apoptosis and immune responses by acting as a ligand for receptor for advanced glycation end products (RAGE), Toll-like receptors (TLRs), and triggering receptor expressed on myeloid cells 1. In particular, HMGB1/RAGE is involved in tumor metastasis by inducing matrix metalloproteinase 2 (MMP2) and MMP9 expression. We investigated the associations between genetic variations in HMGB1-related genes and disease-free survival (DFS) and overall survival (OS) in Korean female breast cancer patients. METHODS: A total of 2,027 patients in the Seoul Breast Cancer Study were included in the analysis. One hundred sixteen single nucleotide polymorphisms (SNPs) were extracted from eight genes. A multivariate Cox proportional hazards model was used to estimate the hazard ratio and 95% confidence interval (CI) of each SNP. The effects of the SNPs on breast cancer prognosis were assessed at cumulative levels with polygenic risk scores. RESULTS: The SNPs significantly associated with DFS were rs243867 (hazard ratio, 1.26; 95% CI, 1.05–1.50) and rs243842 (hazard ratio, 1.24; 95% CI, 1.03–1.50); both SNPs were in MMP2. The SNPs significantly associated with OS were rs243842 in MMP2 (hazard ratio, 1.33; 95% CI 1.03–1.71), rs4145277 in HMGB1 (hazard ratio, 1.29; 95% CI, 1.00–1.66), rs7656411 in TLR2 (hazard ratio, 0.76; 95% CI, 0.60–0.98), and rs7045953 in TLR4 (hazard ratio, 0.50; 95% CI, 0.29–0.84). The polygenic risk score results for the DFS and OS patients showed third tertile hazard ratios of 1.72 (95% CI, 1.27–2.34) and 2.75 (95% CI, 1.79–4.23), respectively, over their first tertile references. CONCLUSION: The results of the present study indicate that genetic polymorphisms in HMGB1-related genes are related to breast cancer prognosis in Korean women.

The Effect of Breastfeeding Duration and Parity on the Risk of Epithelial Ovarian Cancer: A Systematic Review and Meta-analysis / 예방의학회지

OBJECTIVES: We conducted a systematic review and meta-analysis to summarize current evidence regarding the association of parity and duration of breastfeeding with the risk of epithelial ovarian cancer (EOC). METHODS: A systematic search of relevant studies published by December 31, 2015 was performed in PubMed and EMBASE. A random-effect model was used to obtain the summary relative risks (RRs) and 95% confidence intervals (CIs). RESULTS: Thirty-two studies had parity categories of 1, 2, and ≥3. The summary RRs for EOC were 0.72 (95% CI, 0.65 to 0.79), 0.57 (95% CI, 0.49 to 0.65), and 0.46 (95% CI, 0.41 to 0.52), respectively. Small to moderate heterogeneity was observed for one birth (p13 months. The summary RRs were 0.79 (95% CI, 0.72 to 0.87), 0.72 (95% CI, 0.64 to 0.81), and 0.67 (95% CI, 0.56 to 0.79), respectively. Only small heterogeneity was observed for <6 months of breastfeeding (p=0.17; Q=18.79, I²=25.5%). Compared to nulliparous women with no history of breastfeeding, the joint effects of two births and <6 months of breastfeeding resulted in a 0.5-fold reduced risk for EOC. CONCLUSIONS: The first birth and breastfeeding for <6 months were associated with significant reductions in EOC risk.

Association of Selected Medical Conditions With Breast Cancer Risk in Korea / 예방의학회지

OBJECTIVES: To estimate the effect of medical conditions in the population of Korea on breast cancer risk in a case-control study. METHODS: The cases were 3242 women with incident, histologically confirmed breast cancer in two major hospitals interviewed between 2001 and 2007. The controls were 1818 women each admitted to either of those two hospitals for a variety of non-neoplastic conditions. Information on each disease was obtained from a standardized questionnaire by trained personnel. Odds ratios (ORs) for each disease were derived from multiple logistic regression adjusted for age, age of menarche, pregnancy, age of first pregnancy, and family history of breast cancer. RESULTS: Among all of the incident breast cancer patients, pre-existing diabetes (OR, 1.33; 95% confidence interval [CI], 0.99 to 1.78), hypertension (OR, 1.46; 95% CI, 1.18 to 1.83), thyroid diseases (OR, 1.26; 95% CI, 1.00 to 1.58), and ovarian diseases (OR, 1.70; 95% CI, 1.23 to 2.35) were associated with an increased risk of breast cancer when other factors were adjusted for. In a stratified analysis by menopausal status, pre-existing hypertension (pre-menopause OR, 0.80; 95% CI, 0.48 to 1.34 vs. post-menopause OR, 1.87; 95% CI, 1.44 to 2.43; p-heterogeneity <0.01) and ovarian disease (pre-menopause OR, 4.20; 95% CI, 1.91 to 9.24 vs. post-menopause OR, 1.39; 95% CI, 1.02 to 1.91; p-heterogeneity 0.01) showed significantly different risks of breast cancer. CONCLUSIONS: Our results suggest the possibility that medical conditions such as hypertension affect breast cancer development, and that this can differ by menopausal status. Our study also indicates a possible correlation between ovarian diseases and breast cancer risk.

Retrospective Analysis of Adverse Reactions to Iodinated Contrast Media in Korean

BACKGROUND: This study was performed to evaluate the prevalence and risk factors on the adverse reactions caused by iodinated contrast media (CM) for computed tomography (CT) examination in a university hospital. METHODS: Clinical and demographic data among outpatients with CM use were collected at 0000 University Busanpaik Hospital in Busan, Korea between 2008 and 2010. Adverse reaction rate was calculated by the number of adverse reaction among total outpatients with CM use, which was stratified by seasons and sex. The association of risk factors on adverse reaction was investigated using logistic regression model. RESULTS: The total outpatients and events of administered CMs were 27,587 and 48,616, respectively. The administered CMs were iopromide, iohexol, iobitridol, and iodixanol. Adverse reactions occurred in 300 outpatients among the total outpatients (1.1 %). The number of outpatients administered CM more than twice were 8,348. Among them, outpatients who experienced adverse reaction(s) more than once and twice were 124 (1.5 %) and 26 (0.3 %), respectively. Adverse reaction rate was significantly different by sex(p=0.01). The other risk factors were cancer history (OR 2.57, 95 % CI 2.00-3.31) and previous CM administration (OR 1.89, 95 % CI 1.47-2.44). Urticaria was the most frequent symptoms. CONCLUSION: Total adverse reaction rate was 1.1 % with most common symptom in skin system. Related risk factors were female, cancer history, and previous CM administration. These results were similar to previous studies and will be contribute to clinical practice and future research especially in Koreans.

Retrospective Analysis of Adverse Reactions to Iodinated Contrast Media in Korean

BACKGROUND: This study was performed to evaluate the prevalence and risk factors on the adverse reactions caused by iodinated contrast media (CM) for computed tomography (CT) examination in a university hospital. METHODS: Clinical and demographic data among outpatients with CM use were collected at 0000 University Busanpaik Hospital in Busan, Korea between 2008 and 2010. Adverse reaction rate was calculated by the number of adverse reaction among total outpatients with CM use, which was stratified by seasons and sex. The association of risk factors on adverse reaction was investigated using logistic regression model. RESULTS: The total outpatients and events of administered CMs were 27,587 and 48,616, respectively. The administered CMs were iopromide, iohexol, iobitridol, and iodixanol. Adverse reactions occurred in 300 outpatients among the total outpatients (1.1 %). The number of outpatients administered CM more than twice were 8,348. Among them, outpatients who experienced adverse reaction(s) more than once and twice were 124 (1.5 %) and 26 (0.3 %), respectively. Adverse reaction rate was significantly different by sex(p=0.01). The other risk factors were cancer history (OR 2.57, 95 % CI 2.00-3.31) and previous CM administration (OR 1.89, 95 % CI 1.47-2.44). Urticaria was the most frequent symptoms. CONCLUSION: Total adverse reaction rate was 1.1 % with most common symptom in skin system. Related risk factors were female, cancer history, and previous CM administration. These results were similar to previous studies and will be contribute to clinical practice and future research especially in Koreans.

Association between Genetic Polymorphisms of CYP2D6 and Outcomes in Breast Cancer Patients with Tamoxifen Treatment

The aim of the study was to evaluate the association between genetic polymorphisms of CYP2D6 and outcomes in breast cancer patients with tamoxifen treatment. We evaluated the CYP2D6 genetic polymorphisms in 766 breast cancer patients. Among them, 110 patients whose samples were prospectively collected before surgery and treated with tamoxifen were included to evaluate the association between CYP2D6 and outcomes. The genotypes of CYP2D6 were categorized as extensive metabolizer (EM), intermediate metabolizer (IM), and poor metabolizer (PM) according to the activity score. The clinicopathologic features of 110 patients were not significantly different among the three groups except for the T-stage and nodal status. The high T-stage and axillary metastasis were more frequent in the PM group. While recurrence-free and overall survival in the PM group was poorer than the other groups, there was no significant difference between the EM and the IM group. The difference between the PM and the other groups on univariate analysis disappeared on multivariate analysis. These conflicting results suggest that the clinical value of CYP2D6 polymorphisms is still unclear and more large-sized and comprehensively designed trials are necessary.

Genetic Polymorphism of Geranylgeranyl Diphosphate Synthase (GGSP1) Predicts Bone Density Response to Bisphosphonate Therapy in Korean Women

PURPOSE: Genetic factor is an important predisposing element influencing the susceptibility to osteoporosis and related complications. The purpose of the present study is to investigate whether genetic polymorphisms of farnesyl diphosphate synthase (FDPS) or geranylgeranyl diphosphate synthase (GGPS) genes were associated with the response to bisphosphonate therapy. MATERIALS AND METHODS: In the present study, 144 Korean women with osteoporosis were included. Among 13 genetic polymorphisms found within the FDPS and GGPS1 gene, 4 genetic polymorphisms with frequencies > 5% were selected for further study. Bone mineral density (BMD) response after 1 year treatment of bisphosphonate therapy was analyzed according to the genotypes. RESULTS: Women with 2 deletion allele of GGPS1 -8188A ins/del (rs3840452) had significantly higher femoral neck BMD at baseline compared with those with one or no deletion allele (0.768 +/- 0.127 vs. 0.695 +/- 0.090 respectively; p = 0.041). The response rate of women with 2 deletion allele of GGPS1 -8188A ins/del (28.6%) was significantly lower than the rate of women with one (81.4%) or no deletion allele (75.0%) (p = 0.011). Women with 2 deletion allele of GGPS1 -8188A ins/del had 7-fold higher risk of non-response to bisphosphonate therapy compared with women with other genotypes in GGPS1 -8188 after adjusting for baseline BMD (OR = 7.48; 95% CI = 1.32-42.30; p = 0.023). Other polymorphisms in FDPS or GGPS1 were not associated with lumbar spine BMD or femoral neck BMD. CONCLUSION: Our study suggested that GGPS1 - 8188A ins/del polymorphism may confer susceptibility to femoral neck BMD response to bisphosphonate therapy in Korean women. However, further study should be done to confirm the results in a larger population.

Erratum / 예방의학회지

There was an error in the numbering of the references in page 375-376: Sue K. Park, Ji-Yeob Choi. Risk Assessment and Pharmacogenomics in Molecular and Genomic Epidemiology. J Prev Med Public Health 2009; 42(6): 371-6.

Identification and Validation of Osteoporotic Hip Fracture Using the National Health Insurance Database

PURPOSE: The aim of this study was to develop and validate identification criteria for the cases of osteoporotic hip fracture using the National Health Insurance Database, and we calculated the incidence rate of osteoporotic hip fracture in the Korean population using these criteria. MATERIALS AND METHODS: The criteria to identify osteoporotic hip fracture using a diagnosis code, a procedure code, the type and number of medical service usages and the patients' ages were developed via discussions among experts. These criteria were validated by using a hip fracture cohort in which all the genuine osteoporotic hip fracture patients in the Jeju area were identified by reviewing the registered medical records and radiographs. By applying the identification criteria to the National Health Insurance Database that was accumulated until June 2009, we calculated the incidence rate of osteoporotic hip fracture in patients between 50 and 100 years of age in 2008. RESULTS: The identification criteria had a sensitivity of 93.1% and a positive predictive value of 77.4%. A total of 20,432 osteoporotic hip fracture cases were identified in 2008, and the incidence rate was 15.7 cases per 10,000 persons. The osteoporotic hip fracture incidence rate for females was 20.7 (per 10,000persons), and this was 2.1 times higher than that for the males (9.8case per 10,000persons), and the rates were increased with age. CONCLUSION: The incidence of osteoporotic hip fracture that occurred on a nationwide scale can be more precisely estimated by using the National Health Insurance Database with its comprehensive information on the overall details of treatment as well as the diagnosis codes, and so the incidence of osteoporotic hip fracture can be reliably calculated for each year. The results from this research could be used as evidence in a hip fracture management plan for establishing Korean Health policy.

Medical Service Utilization with Osteoporosis

BACKGROUND: Although osteoporosis is increasing in the elderly population, attempts to analyze the patterns of medical service utilization for osteoporosis are currently not sufficient. The medical services and treatment patterns were investigated using Korea's National Health Insurance claims data, which includes all of the Korean population. METHODS: Through the patient identification algorithm developed by using the administrative claims data in 2007, the adult patients (between 50-100 years) with osteoporosis were identified. The age and gender of the patients who used medical service for osteoporosis were described, in relation with six dichotomous variables. The medical service use patterns such as the type of medical institution and conducting bone mineral density measurement were investigated. RESULTS: The number of patients who used medical service were 1,230,580 (females 89.9%). Sixty one point six percent of the patients were prescribed osteoporosis medicine (indicated for osteoporosis only), and 12.9% of the patients had experienced osteoporotic fracture. The primary medical institutions for treatment were clinics (54.3%), while hospitals were mainly used among the patients with a history of fracture and disease or drug use that may induce secondary osteoporosis. The number of visited medical institutions was 6.4 (as an outpatient) and 0.2 (as admissions) during 6 months. The proportion of patients who conducted bone mineral density measurements within one year before and after the diagnosis of osteoporosis was 66.7% and DXA was the most frequently used densitometry (46.3%). The average number of days for the prescriptions for osteoporosis medicine was 70 days. CONCLUSION: In order to prevent further osteoporotic fractures, appropriate management and treatment should be implemented for osteoporosis patients. To do this, we need to understand the current state of medical service utilization and the treatment of osteoporosis using the National Health Insurance claims data.

Risk Assessment and Pharmacogenetics in Molecular and Genomic Epidemiology / 예방의학회지

In this article, we reviewed the literature on risk assessment (RA) models with and without molecular genomic markers and the current utility of the markers in the pharmacogenetic field. Epidemiological risk assessment is applied using statistical models and equations established from current scientific knowledge of risk and disease. Several papers have reported that traditional RA tools have significant limitations in decision-making in management strategies for individuals as predictions of diseases and disease progression are inaccurate. Recently, the model added information on the genetic susceptibility factors that are expected to be most responsible for differences in individual risk. On the continuum of health care, from diagnosis to treatment, pharmacogenetics has been developed based on the accumulated knowledge of human genomic variation involving drug distribution and metabolism and the target of action, which has the potential to facilitate personalized medicine that can avoid therapeutic failure and serious side effects. There are many challenges for the applicability of genomic information in a clinical setting. Current uses of genetic markers for managing drug therapy and issues in the development of a valid biomarker in pharmacogenetics are discussed.

Cytochrome P450 1A1 (CYP1A1) polymorphisms and breast ancer risk in Korean women

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. Haplotype 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.