Implementing Massive Parallel Sequencing into Biliary Samples Obtained through Endoscopic Retrograde Cholangiopancreatography for Diagnosing Malignant Bile Duct Strictures.

Despite advancements in radiologic, laboratory, and pathological evaluations, differentiating between benign and malignant bile duct strictures remains a diagnostic challenge. Recent developments in massive parallel sequencing (MPS) have introduced new opportunities for early cancer detection and management, but these techniques have not yet been rigorously applied to biliary samples. We prospectively evaluated the Oncomine Comprehensive Assay (OCA) and the Oncomine Pan-Cancer Cell-Free Assay (OPCCFA) using biliary brush cytology and bile fluid obtained via endoscopic retrograde cholangiopancreatography from patients with bile duct strictures. The diagnostic performance of MPS testing was assessed and compared to the pathological findings of biliary brush cytology and primary tissue. Mutations in TP53, BRAF, CTNNB1, SMAD4, and K-/N-RAS identified in biliary brush cytology samples were also detected in the corresponding bile fluid samples from patients with extrahepatic cholangiocarcinoma. These mutations were also identified in the bile fluid samples, but with variant allele frequencies lower than those in the corresponding biliary brush cytology samples. In control patients diagnosed with gallstones, neither the biliary brush cytology samples nor the bile fluid samples showed any pathogenic mutations classified as tier 1 or 2. Our study represents a prospective investigation into the role of MPS-based molecular testing in evaluating bile duct strictures. MPS-based molecular testing shows promise in identifying actionable genomic alterations, potentially enabling the stratification of patients for targeted chemotherapeutic treatments. Future research should focus on integrating OCA and OPCCFA testing, as well as similar MPS-based assays, into existing surveillance and management protocols for patients with bile duct strictures.

Comparative Analysis of Clinical Outcomes Using Propensity Score Matching: Coronavirus Disease 2019 vs. Seasonal Influenza in Korea.

BACKGROUND: The advent of the omicron variant and the formulation of diverse therapeutic strategies marked a new epoch in the realm of coronavirus disease 2019 (COVID-19). Studies have compared the clinical outcomes between COVID-19 and seasonal influenza, but such studies were conducted during the early stages of the pandemic when effective treatment strategies had not yet been developed, which limits the generalizability of the findings. Therefore, an updated evaluation of the comparative analysis of clinical outcomes between COVID-19 and seasonal influenza is requisite. METHODS: This study used data from the severe acute respiratory infection surveillance system of South Korea. We extracted data for influenza patients who were infected between 2018 and 2019 and COVID-19 patients who were infected in 2021 (pre-omicron period) and 2022 (omicron period). Comparisons of outcomes were conducted among the pre-omicron, omicron, and influenza cohorts utilizing propensity score matching. The adjusted covariates in the propensity score matching included age, sex, smoking, and comorbidities. RESULTS: The study incorporated 1,227 patients in the pre-omicron cohort, 1,948 patients in the omicron cohort, and 920 patients in the influenza cohort. Following propensity score matching, 491 patients were included in each respective group. Clinical presentations exhibited similarities between the pre-omicron and omicron cohorts; however, COVID-19 patients demonstrated a higher prevalence of dyspnea and pulmonary infiltrates compared to their influenza counterparts. Both COVID-19 groups exhibited higher in-hospital mortality and longer hospital length of stay than the influenza group. The omicron group showed no significant improvement in clinical outcomes compared to the pre-omicron group. CONCLUSION: The omicron group did not demonstrate better clinical outcomes than the pre-omicron group, and exhibited significant disease severity compared to the influenza group. Considering the likely persistence of COVID-19 infections, it is imperative to sustain comprehensive studies and ongoing policy support for the virus to enhance the prognosis for individuals affected by COVID-19.

The Changes in Respiratory and Enteric Adenovirus Epidemiology in Korea From 2017 to June 2022.

Since October 2021, severe acute hepatitis of unknown etiology in pediatric patients has been observed in many countries around the world. Adenovirus (mainly enteric adenovirus) was detected in more than 50% of the cases. Nationwide surveillance on acute hepatitis of unknown etiology in pediatric patients was started in May 2022 in Korea. Taking into account the severity of the illness and the urgency of the epidemiological situation worldwide, we report a summary of changes in adenovirus epidemiology during the past five years and six months in Korea.

Humidifier Disinfectants Are a Cause of Lung Injury among Adults in South Korea: A Community-Based Case-Control Study.

BACKGROUNDS: An outbreak of lung injury among South Korean adults was examined in a hospital-based case-control study, and the suspected cause was exposure to humidifier disinfectant (HD). However, a case-control study with community-dwelling controls was needed to validate the previous study's findings, and to confirm the exposure-response relationship between HD and lung injury. METHODS: Each case of lung injury was matched with four community-dwelling controls, according to age (±3 years), sex, residence, and history of childbirth since 2006 (for women). Environmental risk factors, which included type and use of humidifier and HD, were investigated using a structured questionnaire during August 2011. The exposure to HD was calculated for both cases and controls, and the corresponding risks of lung injury were compared. RESULTS: Among 28 eligible cases, 16 patients agreed to participate, and 60 matched controls were considered eligible for this study. The cases were more likely to have been exposed to HD (odds ratio: 116.1, 95% confidence interval: 6.5-2,063.7). All cases were exposed to HDs containing polyhexamethyleneguanidine phosphate, and the risk of lung injury increased with the cumulative exposure, duration of exposure, and exposure per day. CONCLUSIONS: This study revealed a statistically significant exposure-response relationship between HD and lung injury. Therefore, continuous monitoring and stricter evaluation of environmental chemicals' safety should be conducted.

Nationwide Study of Humidifier Disinfectant Lung Injury in South Korea, 1994-2011. Incidence and Dose-Response Relationships.

RATIONALE: Humidifier disinfectant lung injury is an acute lung disease attributed to recurrent inhalation of certain disinfectant aerosols emitted from room humidifiers. An outbreak of this toxic lung injury occurred in South Korea from 1995 until all humidifier disinfectant products were recalled from the consumer market by the government in 2011. OBJECTIVES: A nationwide study was conducted to ascertain and classify all potential cases of humidifier disinfectant lung injury in Korea and to assess dose-response relationships. METHODS: By several mechanisms, clinicians and the general public were invited to report all suspected cases of humidifier disinfectant lung injury to public health officials in South Korea. A committee was convened to define diagnostic criteria based on pathologic, radiologic, and clinical findings for index cases, combined with assessment of environmental exposure to humidifier disinfectants. Clinical review and environmental assessments were performed and later combined to determine overall likelihood of disease for each study participant, classified as definite, probable, possible, or unlikely. Survival time from exposure to onset of symptoms was analyzed to assess dose-response relationships. Three broad categories of risk factors were examined: (1) biological susceptibility, (2) temporal cycle of exposure and recovery, and (3) spatial conditions and density of disinfectant. MEASUREMENTS AND MAIN RESULTS: Of 374 possible cases identified and reviewed, 329 were unanimously classified by the diagnostic committee, as follows: 117 definite, 34 probable, 38 possible and 140 unlikely cases. A total of 62 individuals with definite or probable disease died. Risk factors examined for polyhexamethyleneguanidine phosphate exposure that were found to be significant in shortening survival included age 4 years or younger at onset, use of disinfectant for 7 days per week, airborne density of 800 µg/m(3) or more of disinfectant, and daily exposure 11 or more hours in duration. CONCLUSIONS: Dose-response analysis indicated that development of humidifier disinfectant lung injury and death were associated strongly with recurrent, intense, acute exposure without sufficient recovery time between exposures, more so than long-term cumulative exposure. These findings may explain some reversible or clinically unapparent cases among coexposed family members.

A cluster of lung injury cases associated with home humidifier use: an epidemiological investigation.

BACKGROUND: In April 2011 a tertiary hospital in Seoul, Korea reported several cases of severe respiratory distress of unknown origin in young adults. METHODS: To find the route of transmission, causative agent and patient risk factors of the outbreak, an investigation of the epidemic was initiated. Clinicopathological conferences led to the suspicion that the cases related to an inhalation injury. An age- and sex-matched case-control study was therefore performed to examine the inhalation exposure of the patients to various agents. RESULTS: Of the 28 confirmed cases, 18 agreed to participate. A total of 121 age- and sex-matched controls with pulmonary, allergic or obstetric disease were selected. All patients and controls completed questionnaires with questions about exposure to various inhalants. The crude ORs for patient exposure to indoor mould, humidifier use, humidifier detergent use and insecticide use were 4.4 (95% CI 1.5 to 13.1), 13.7 (95% CI 1.8 to 106.3), 47.3 (95% CI 6.1 to 369.7) and 3.9 (95% CI 1.3 to 11.7), respectively. However, when considered concurrently, indoor mould and insecticide use lost statistical significance. Moreover, humidifier use was ruled out as the cause because of a lack of biological plausibility and the weak strength of the association. This suggested that humidifier disinfectant was the cause of the outbreak. This information led the Korean government to order the removal of humidifier detergents from the market. In the years following the ban, no additional cases were detected. CONCLUSIONS: Epidemiological evidence strongly suggests that the lung injury outbreak was caused by humidifier detergent use at home.

Intake of soy products and other foods and gastric cancer risk: a prospective study.

BACKGROUND: Gastric cancer, the most common cancer in the world, is affected by some foods or food groups. We examined the relationship between dietary intake and stomach cancer risk in the Korean Multi-Center Cancer Cohort (KMCC). METHODS: The KMCC included 19 688 Korean men and women who were enrolled from 1993 to 2004. Of those subjects, 9724 completed a brief 14-food frequency questionnaire at baseline. Through record linkage with the Korean Central Cancer Registry and National Death Certificate databases, we documented 166 gastric cancer cases as of December 31, 2008. Cox proportional hazard models were used to estimate relative risks (RRs) and 95% CIs. RESULTS: Frequent intake of soybean/tofu was significantly associated with reduced risk of gastric cancer, after adjustment for age, sex, cigarette smoking, body mass index, alcohol consumption, and area of residence (P for trend = 0.036). We found a significant inverse association between soybean/tofu intake and gastric cancer risk among women (RR = 0.41, 95% CI: 0.22-0.78). Men with a high soybean/tofu intake had a lower risk of gastric cancer, but the reduction was not statistically significant (RR = 0.77, 95% CI: 0.52-1.13). There was no interaction between soybean/tofu intake and cigarette smoking in relation to gastric cancer risk (P for interaction = 0.268). CONCLUSIONS: Frequent soybean/tofu intake was associated with lower risk of gastric cancer.

Viral hepatitis and liver cancer in Korea: an epidemiological perspective.

In the past, hepatitis B virus (HBV) infection was endemic in the general Korean population. The association of HBV infection with the occurrence of liver cancer has been well demonstrated in several epidemiologic studies. While the mortality rates of liver cancer in Korea have decreased steadily over the last decade, the presence of hepatitis B surface antigen (HBsAg) in mothers remains high at 3-4%, and 25.5% of these HBsAg positive mothers are positive for hepatitis B e antigen (HBeAg). HBV infection caused almost a quarter of hepatocellular carcinoma (HCC) cases and one-third of deaths from HCC. These aspects of HBV infection prompted the Korean government to create a vaccination program against HBV in the early 1980s. In 1995, the Communicable Disease Prevention Act (CDPA) was reformed, and the government increased the number of HBV vaccines in the National Immunization Program (NIP), driving the vaccination rate up to 95%. In 2000, the National Health Insurance Act (NHIA) was enacted, which provided increased resources for the prevention of perinatal HBV infection. Then in 2002, the Korean government, in conjunction with the Korean Medical Association (KMA), launched an HBV perinatal transmission prevention program. The prevalence of HBsAg in children had been high (4-5%) in the early 1980s, but had dropped to below 1% in 1995, and finally reached 0.2% in 2006 after the NIP had been implemented. After the success of the NIP, Korea finally obtained its first certification of achievement from the Western Pacific Regional Office of the World Health Organization (WPRO-WHO) for reaching its goal for HBV control. An age-period-cohort analysis showed a significant reduction in the liver cancer mortality rate in children and adolescents after the NIP had been implemented. In addition to its vaccination efforts, Korea launched the National Cancer Screening Program (NCSP) for 5 leading sites of cancer, including the liver, in 1999. As a consequence of this program, the 5-year liver cancer survival rate increased from 13.2% (1996-2000) to 23.3% (2003-2008). The development of both the primary and secondary prevention for liver cancer including HBV immunization and cancer screening has been of critical importance.

Acute health effects among military personnel participating in the cleanup of the hebei spirit oil spill, 2007, in taean county, Korea.

OBJECTIVES: This study was conducted to investigate acute health effects and its related factors among military personnel participating in the cleanup of the 2007 Hebei Spirit oil spill accident in Taean county, Korea. METHODS: We collected data on acute symptoms during the cleanup and their predictors using a self-administered questionnaire to 2624 military personnel. Selfreported symptoms included six neurologic symptoms, five respiratory symptoms, two dermatologic symptoms, three ophthalmic symptoms, and three general symptoms. Independent variables were demographic factors (gender, age, education level, and rank), health behavioral factors (smoking history and usage of the personal protective equipment such as masks and gloves), and occupational history such as where and for how long individuals participated in cleanup. RESULTS: The duration of work days was significantly associated with 17 acute symptoms except for itchiness and red skin.Working in Taean county also increased the risk of most acute symptoms except headache and back pain. In regard to personal protective equipment, wearing masks was mainly related to the development of respiratory symptoms such as sore throat and wearing other protective equipment was related to the development of sore throat, back pain, headache, and cough. Military personnel younger than 25 years reported 4.66 times more hot flushing and 5.39 times more itchiness than those older than 25 years. CONCLUSION: It should be emphasized that for early-stage cleanup the number of workers should be minimized, sufficient personal protective equipment with approved quality for blocking noxious gas should be supplied, and systematic health care for the workers should be provided. Health effects could be diminished by providing adequate education regarding the appropriate use of protective equipment, especially to nonprofessionals such as residents and volunteers. To make disaster response expeditious, a national and regional preparedness plans and a professional response team for emergency environmental assessment and emergency action should be established beforehand to make prompt decisions.

Ecological study for refrigerator use, salt, vegetable, and fruit intakes, and gastric cancer.

We used an ecological approach to determine the correlation between vegetable, fruit and salt intakes, refrigerator use, and gastric cancer mortality in Korean population. Information on fruit and vegetable intakes per capita from the National Health and Nutrition Survey, death certificate data from the National Statistical office, refrigerator per household data from Korean Statistical Information Service, and salt/sodium intake data from a cross-sectional survey were utilized. Correlation coefficients were calculated between vegetable and fruit intakes, refrigerator per household, and gastric cancer mortality and between salt and sodium intakes, and gastric cancer mortality and incidence in the four areas. With 5, 10, and 15 years lag time, refrigerator usage and fruit intake were negatively associated with gastric cancer mortality (p < 0.01), but vegetable intake was not associated with gastric cancer mortality. When estimates of salt/sodium intake evaluated by 24-h urine collection in four areas of Korea were compared to the gastric cancer mortality and incidence in these regions, positive correlation was shown between salt/sodium intake, and gastric cancer incidence and mortality. Negative associations between refrigerator use, fruit intake, and gastric cancer mortality and positive associations between salt/sodium intake and gastric cancer mortality and incidence were suggested.

Hepatitis B vaccination and liver cancer mortality reduction in Korean children and adolescents.

Liver cancer is one of the three most common causes of cancer mortality in the world and it is closely related to chronic hepatitis B viral (HBV) infection in Korea. The decline of HBV prevalence for the last two decades in Korea might be partly due to the HBV vaccination, which was implemented as a national program starting in 1995. The aim of this study was to assess the period effect of the national HBV vaccination on liver cancer mortality in a young population. We compared age-specific mortality rates of liver cancer before and after the national vaccination program in the Korean population under the age of 20. To reduce year-to-year fluctuations in mortality, calendar years and age groups were divided into 4-year strata and the mortality rates were calculated for each stratum. Period effects of the national vaccination program were analyzed using age-period-cohort modeling. A total of 370 liver cancer mortality cases were identified during the period from 1991 to 2006. The period effect of the national vaccination program for the period 2002-2006 had a significantly reduced liver cancer mortality rate when compared to the period 1991-1994 when the national vaccination program was not implemented (RR 0.30, 95% CI 0.21~0.44). After implementation of the national vaccination program, HBV prevalence in Korean declined from 6~8% to 2~3%. This study demonstrates that the national vaccination program has contributed to the reduction of liver cancer mortality beyond just a natural decrease in Korean children and adolescents.

Isoflavones from phytoestrogens and gastric cancer risk: a nested case-control study within the Korean Multicenter Cancer Cohort.

BACKGROUND: The role of soybean products in gastric cancer risk is not clear in epidemiologic studies due to measurement error from dietary intake questionnaires and due to different degrees of bias according to study design. To examine the association between soybean products and gastric cancer risk, we measured phytoestrogen biological markers in a nested case-control study. METHODS: The study population was composed of 131 cases and 393 matched controls within the Korean Multicenter Cancer Cohort. The concentrations of the four biomarkers in the plasma samples were measured using time-resolved fluoroimmunoassay. Conditional and unconditional logistic regression models were used to compute the odds ratio (OR) and 95% confidence intervals (CI). RESULTS: Median plasma concentrations of genistein (229 nmol/L for controls, 181.8 nmol/L for cases; P=0.07) and daidzein (131.2 nmol/L for controls, 80.5 nmol/L for cases; P=0.04) in cases were lower than in controls, whereas equol concentrations were similar. Compared with the reference group, gastric cancer risk decreased in the highest groups for genistein (OR, 0.54; 95% CI, 0.31-0.93) and daidzein (OR, 0.21; 95% CI, 0.08-0.58). Higher equol concentrations were associated with a decreased risk for gastric cancer (OR, 0.50; 95% CI, 0.27-0.90). The combination of the highest concentrations for each isoflavone category was associated with a 0.09-fold decreased risk for gastric cancer compared with the combination of the lowest concentrations for each category. There was no association between plasma lignan concentrations and gastric cancer. CONCLUSIONS: High serum concentrations of isoflavones were associated with a decreased risk for gastric cancer. IMPACT: These results suggest a beneficial effect of high soybean product intake for gastric cancer risk.

The role of TNF genetic variants and the interaction with cigarette smoking for gastric cancer risk: a nested case-control study.

BACKGROUND: The aim of this study was to investigate the role of TNF genetic variants and the combined effect between TNF gene and cigarette smoking in the development of gastric cancer in the Korean population. METHODS: We selected 84 incident gastric cancer cases and 336 matched controls nested within the Korean Multi-Center Cancer Cohort. Six SNPs on the TNF gene, TNF-alpha-238 G/A, -308 G/A, -857 C/T, -863 C/A, -1031 T/C, and TNF-beta 252 A/G were genotyped. The ORs (95% CIs) were calculated using unconditional logistic regression model to detect each SNP and haplotype-pair effects for gastric cancer. The combined effects between the TNF gene and smoking on gastric cancer risk were also evaluated. Multi dimensionality reduction (MDR) analyses were performed to explore the potential TNF gene-gene interactions. RESULTS: TNF-alpha-857 C/T containing the T allele was significantly associated with an increased risk of gastric cancer and a linear trend effect was observed in the additive model (OR = 1.6, 95% CI 1.0-2.5 for CT genotype; OR = 2.6, 95% CI 1.0-6.4 for TT genotype). All haplotype-pairs that contained TCT or CCC of TNF-alpha-1031 T/C, TNF-alpha-863 C/A, and TNF-alpha-857 C/T were associated with a significantly higher risk for gastric cancer only among smokers. In the MDR analysis, regardless of smoking status, TNF-alpha-857 C/T was included in the first list of SNPs with a significant main effect. CONCLUSION: TNF-alpha-857 C/T polymorphism may play an independent role in gastric carcinogenesis and the risk for gastric cancer by TNF genetic effect is pronounced by cigarette smoking.

Soybean product intake modifies the association between interleukin-10 genetic polymorphisms and gastric cancer risk.

In this study, our aim was to investigate the association of inflammation-related genetic polymorphisms and gastric cancer risk and to examine whether the combined effect of soybean product intake modified cancer risk. Eighty-four incident gastric cancer cases and 336 matched controls were selected from the Korean Multi-Center Cancer Cohort. We selected 14 single nucleotide polymorphisms (SNP) from 5 genes [interleukin (IL)-1beta, IL-2, IL-4, IL-8, and IL-10] and used unconditional logistic regression model to calculate the odds ratios (OR) and 95% CI adjusting for H. pylori seropositivity, smoking, age, sex, enrollment year, and residential area. The risk for gastric cancer in relation to genetic polymorphisms and haplotypes were assessed according to soybean product intake levels. Although no single SNP effect was found, the combined effect between IL-10 gene variants of -592 GG/GA, -819 TC/CC, or -1082 AG/GG and low intake of soybean products had an increased risk for gastric cancer compared with the group with no risk gene variants and a high intake of soybean products (OR [95% CI] = 2.82 [1.04-7.62], 2.75 [1.02-7.44], and 4.34 [1.51-12.5], respectively). Among the low-soybean product intake group, IL-10 CCG haplotype had an increased risk of gastric cancer (OR = 3.38 [1.40-8.13]) relative to the ATA haplotype. Our results suggest that the association between IL-10 genetic polymorphisms and gastric cancer risk was modified by soybean product intake.

Disparities between persons with and without disabilities in their participation rates in mass screening.

OBJECTIVES: The purpose of this study was to determine the number of persons with and without disabilities who participated in the National Health Insurance (NHI) chronic disease mass screening programs in South Korea. METHODS: The data were obtained from mass screening claims submitted to the NHI and National Disability Registry. Factors affecting the participation rate included demographic variables, socioeconomic status, residential region, and disability type and severity. A multiple logistic regression analysis was used to evaluate the relationship between participation rates and disability type and severity adjusted for confounding factors. RESULTS: The analysis revealed that persons with a disability were less likely to participate in mass screening programs than those without a disability (35.8% vs. 40.2%). Multiple logistic regression analysis indicated that persons with severe disabilities had lower participation rates than those without disabilities [adjusted odds ratio (aOR): 0.64, 95% confidence interval (CI): 0.63-0.64]. In particular, persons with severe disabilities such as limb, brain, visual and internal organ impairment, were less likely to participate in the mass screening programs. However, persons with mild disability had higher participation rates than those without disabilities (1.03, 1.02-1.03). CONCLUSIONS: Although the prevalence rates of chronic diseases are higher among persons with disabilities, various types of impairments such as limb, brain, visual and internal organ impairment, hinder participation in mass screening programs for chronic diseases. The reasons for this disparity must be investigated and health policies must be altered to make preventative treatments more accessible to persons with disabilities.

[Reliability of a questionnaire for women's reproductive history].

OBJECTIVES: This study was performed to evaluate the reproducibility of a questionnaire concerned with reproductive history and to ascertain which characteristics of the subjects (age, the visit-revisit intervals, education and chronic disease) are associated with good reliability in the Korean Multi-Center Cancer Cohort (KMCC) study. MATERIALS AND METHODS: A total of 19,688 participants were enrolled between 1993 and 2004. Among them, we selected 386 participants who were aged 40 or more and who re-visited within 8 years after the first visit. Reliability was measured by the percent agreement according to error range for the continuous variables and the percent agreement and kappa statistics for the categorical variables. RESULTS: The pregnancy histories were reliable (kappa=0.67) and the reasons for being menopausal among the postmenopausal women were also reliable (kappa=0.92). The percent agreement of the breast-feeding history was high (96.1%), although the kappa statistic was low. For the continuous variables, when the error range of one variable was considered to be reliable, the percent agreement of the age at menarche and the age at the first full term pregnancy was good (69.4% and 83.6%), whereas that of the age at menopause was low (51.5%). The factors associated with high reliability were a younger age, the presence of chronic disease and a short visit-revisit time interval. CONCLUSIONS: The agreements for parity, the reasons for menopause, and the breastfeeding history in the reproductive history questionnaire used in the KMCC were relatively good. The questionnaire for the menarche age and the menopausal age might have lower reliability due to the difference between Korean age and American age. To obtain reliable information, more attention should be given to the items in questionnaire-based surveys, and especially for surveying old-aged women.

[Cigarette smoking and gastric cancer risk in a community-based cohort study in Korea].

OBJECTIVES: Gastric cancer is the most common incident cancer in Korea. Although Helicobacter pylori infection is the most important risk factor for the development of gastric cancer, cigarette smoking has also been suggested to play an important role in the development of gastric cancer. The objective of this study is to evaluate the relationship between cigarette smoking and gastric cancer risk in a Korean population. METHODS: The study population consisted of 13,785 subjects who had been enrolled in the Korean Multi-Center Cancer Cohort between 1993 and 2002. As of December 2002, 139 incident gastric cancer cases were ascertained through the Korea Central Cancer Registry and the National Death Certificate Database. Relative risks (RR) and 95% confidence intervals (CI) for gastric cancer were estimated using Cox's proportional hazard model adjusted for age, education, alcohol drinking status and history of gastritis or ulcer. RESULTS: Significant dose-response relationships were observed between the duration of smoking and the risk of gastric cancer among the male subjects in comparison to non-smokers: men who smoked for 20-39 years had a 2.09- fold (95% CI 1.00-4.38) increase, and those who smoked for more than 40 years had a 3.13-fold (95% CI 1.59-6.17) increase in the risk of gastric cancer (P trend<0.01). CONCLUSIONS: This study suggests that a longer duration of cigarette smoking may increase the risk of gastric cancer development in a dose-response manner in Korean men. The association between smoking and gastric cancer risk in women should be verified in future studies with a larger number of cases.

[Cigarette smoking, alcohol consumption, tuberculosis and risk of lung cancer: the Korean multi-center cancer cohort study].

OBJECTIVES: The aim of this study was to evaluate the roles of cigarette smoking, alcohol consumption, tuberculosis, and their interactions in the risk of lung cancer in a Korean cohort. METHODS: The study subjects comprised 13,150 males and females aged above 20 years old. During the follow up period from 1993 to 2002, 79 lung cancer cases were identified by the central cancer registry and the national death certificate database. Information on cigarette smoking, alcohol consumption and the history of physician-diagnosed tuberculosis was obtained by interview. Indirect chest X-ray findings were also evaluated to ascertain tuberculosis cases. Cox proportional hazard models were used to estimate relative risks (RR) and 95% confidence intervals (CI) after adjusting for age and gender. RESULTS: Cigarette smoking was statistically significantly associated with an increased risk of lung cancer [for current smokers, RR = 2.33 (95% CI = 1.23 - 4.42) compared to non-smokers]. After further adjustment for cigarette smoking, both alcohol consumption and tuberculosis showed no statistically significant association with the risk of lung cancer [for current drinkers, RR = 0.80 (95% CI = 0.48 - 1.33) compared to non-drinkers] [for tuberculosis cases, RR = 1.17 (95% CI = 0.58 - 2.36) compared to non-cases]. There was no statistically significant interaction between cigarette smoking and alcohol consumption (p-interaction = 0.38), or cigarette smoking and tuberculosis (p-interaction = 0.74). CONCLUSIONS: Although cigarette smoking was confirmed as a risk factor of lung cancer in this cohort study, this study suggests that alcohol consumption and tuberculosis may not be associated with the risk of lung cancer.

[Fasting serum glucose and subsequent liver cancer risk in a Korean prospective cohort].

OBJECTIVES: Chronic infections with hepatitis B or C and alcoholic cirrhosis are three well-known major risk factors for liver cancer. Diabetes has also been suggested as a potential risk factor. However, the findings of previous studies have been controversial in terms of the causal association. Therefore, the aim of this study was to evaluate the association between serum glucose levels and liver cancer development in a Korean cohort. METHODS: Thirty-six liver cancer cases were identified in the Korean Multi-Center Cancer Cohort (KMCC). Baseline information on lifestyle characteristics was obtained via questionnaire. Serum glucose levels were measured at the study's enrollment. Relative risks (RRs) were estimated using a Cox proportional hazard regression model. The adjusting variables included age, gender, smoking history, alcohol consumption, body mass index, and hepatitis B surface antigen (HBsAg) seropositivity. RESULTS: The RRs of serum glucose for liver cancer were 1.20 (95% CI = 0.48-2.99) for the category of 100 to 125 mg/dL of serum glucose and 2.77 (95% CI = 1.24-6.18) for the > 126 mg/dL serum glucose category (both compared to the < 100 mg/dL category). In a subgroup analysis, the RR of serum glucose among those who were both HBsAg seronegative and non-drinkers was 4.46 (95% CL = 1.09-18.28) for those with glucose levels > 100 mg/dL. CONCLUSIONS: The results of this study suggest that a high level of serum glucose can increase liver cancer risk independently of hepatitis infection and drinking history in Koreans. This study implies that glucose intolerance may be an independent risk factor for liver cancer.

[Fasting serum glucose level and gastric cancer risk in a nested case-control study].

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.