Incidence In Korea Research Articles

Decline in the Incidence of All-Cause and Alzheimer's Disease Dementia: a 12-Year-Later Rural Cohort Study in Korea.

BackgroundThere has been no study on the time trends of dementia incidence in Korea. We report the 5-year incidence and its correlates of all-cause and Alzheimer's disease (AD) dementia, and compared our results with those of a 12-year-prior cohort study conducted in the same area.MethodsA total of 751 community-dwelling older adults were followed up for a mean duration of 5.4 years. The age-, gender-, and educational attainment-specific incidence of all-cause and AD dementia were reported as cases per 1,000 person-years. We performed univariate and multivariate cox proportional hazard regression analyses to determine whether baseline sociodemographic, lifestyle, and clinical variables were associated with the risk of all-cause and AD dementia. A 12-year-prior cohort study was used for descriptive comparison to indicate the time trends of dementia incidence.ResultsThe incidence rates were 16.2 and 13.0 cases per 1,000 person-years for all-cause and AD dementia, respectively. The baseline diagnosis of mild cognitive impairment increased the 5-year incidence of all-cause dementia by more than 4-fold. Old age and low baseline global cognitive function were noted as risk factors for both all-cause and AD dementia.ConclusionUpon comparing the results with those from the earlier cohort study in Yeoncheon, the incidence of all-cause and AD dementia decreased by approximately 40% over 12 years; it has been mainly driven by the increase in the educational level of older adults. The declining time trends of incidence should be taken into account for estimating the future prevalence of dementia in Korea.

An Ecological Study on the Risk of Gastric Cancer With Helicobacter Pylori Prevalence and Other Potential Cofactors in Korea

Background: Korea has a high incidence of gastric cancer and a high prevalence of Helicobacter pylori infection. Observation of prevalence trends and determination of risk factors for gastric cancer are important to establish health policies to prevent and reduce the burden of disease. Currently, there is no evidence of complete correlation between prevalence of H. pylori infection and the occurrence of gastric cancer. Several explanations have been proposed for the paradox of high prevalence of infection and low gastric cancer incidence in certain places, including diet and salt consumption, genetic susceptibility, other infections, aflatoxin-contaminated food, and the interaction of all these factors, but none of them has been clearly established. Aim: To explore the potential effects of prevalence of H. pylori infection and other risk factors on gastric cancer incidence in Korea. Methods: Information on gastric cancer incidence, prevalence of H. pylori infection, and the risk factors for gastric cancer were evaluated from nationally representative data - the Korean National Cancer Registry, nationwide routine health check-up surveillance system, and National Health and Nutrition Survey, respectively. Secular trends of H. pylori infection prevalence and age-standardized incidence rates for gastric cancer by region were examined. Furthermore, trends of income level, education level, marital status, number of family members, smoking status, drinking status, obesity, diabetes, hypertension, dyslipidemia, and age-standardized incidence rates for gastric cancer by region were examined. Results: Gastric cancer incidence showed a decreasing trend from 2011 to 2015; 50.6%–44.4% for men and 22.1%–17.0% for women. The prevalence of H. pylori infection also showed a decreasing trend; from 66.9% in 1998%–54.4% in 2011. In Korea, areas with high prevalence of H. pylori infection also showed high gastric cancer incidence. However, the Chungcheong area showed relatively low prevalence of H. pylori infection, but had the highest gastric cancer incidence in Korea. Other factors which showed similar effects on gastric cancer incidence, like H. pylori infection were large family size (4 or more family members), low income, low education, and obesity. The effect of introduction of 'National Cancer Screening Program' will be evaluated in the final outcome. Conclusion: The results of this study indicated that significant regional differences exist between trends in H. pylori infection prevalence and gastric cancer incidence in Korea. Also, the possibility of lack of association between H. pylori prevalence and the incidence of gastric cancer are suggested. Overall, this study suggests the need for further research to explore potential factors accounting for regional differences in gastric cancer incidence in Korea.

The Epidemiological Influence of Climatic Factors on Shigellosis Incidence Rates in Korea.

Research has shown the effects of climatic factors on shigellosis; however, no previous study has evaluated climatic effects in regions with a winter seasonality of shigellosis incidence. We examined the effects of temperature and precipitation on shigellosis incidence in Korea from 2002–2010. The incidence of shigellosis was calculated based on data from the Korean Center for Disease Control and Prevention (KCDC, Cheongju, Korea), and a generalized additive model (GAM) was used to analyze the associations between the incidence and climatic factors. The annual incidence rate of shigellosis was 7.9 cases/million persons from 2002–2010. During 2007–2010, high incidence rates and winter seasonality were observed among those aged ≥65 years, but not among lower age groups. Based on the GAM model, the incidence of shigellosis is expected to increase by 13.6% and 2.9% with a temperature increase of 1 °C and a lag of two weeks and with a mean precipitation increase of 1 mm and a lag of five weeks after adjustment for seasonality, respectively. This study suggests that the incidence of shigellosis will increase with global climate change despite the winter seasonality of shigellosis in Korea. Public health action is needed to prevent the increase of shigellosis incidence associated with climate variations.

Outdoor Air Pollution Exposure and Lung Cancer Incidence in Korea: A Nationwide Population-Based Cohort Study

Background/Aim: The International Agency for Research on Cancer (IARC) has concluded that exposure to outdoor air pollution causes lung cancer. Epidemiological studies on air pollution associated with lung cancer played a crucial role in their decision. However, most of the epidemiological evidence is limited to western countries. We aimed to investigate the association between long-term exposure to outdoor air pollutants and lung cancer incidence in Korea.Methods: National Sample Cohort data from 2002 to 2013 were obtained from National Health Insurance Service in Korea. The study population included a total of 28,090 subjects without pre-existing cancer at baseline. The district level annual-average concentration of particulate matter with a diameter ≤ 10 mm (PM10), nitrogen dioxide (NO2), and ozone (O3) were assigned to each individual based on residential address which is updated annually. Cox-proportional hazard regression model was used to estimate the effects of long-term exposure to air pollution on the incidence of lung cancer. Different exposure matrices and lag years were considered.Results: During 263,178 person-years, 160 incident cases of lung cancer were observed. Increasing yearly mean exposure in 10 ppb O3 was associated incident lung cancer (hazard ratio [HR]: 1.61, 95% CI: 1.07-2.41]). The results showed no association between lung cancer and PM10 (HR: 0.91, 95% CI: 0.72-1.15) or NO2 (HR: 0.84, 95% CI: 0.63-1.10). Each follow-up period average exposure and average cumulative exposure to O3 before censoring were also marginally associated with lung cancer.Conclusion: Lung cancer incidence was most strongly associated with long-term O3 exposure in this Korean study. Further investigation is required to provide strong evidence, however, our study suggests that annual guideline for O3 is recommended in Korea.

Nationwide Analysis of Treatment Patterns for Korean Breast Cancer Survivors Using National Health Insurance Service Data.

BackgroundThe National Health Insurance Service (NHIS) established a healthcare claim database for all Korean citizens. This study aimed to analyze the NHIS data and investigate the patterns of breast cancer treatments.MethodsWe constructed a retrospective female breast cancer cohort by analyzing annual incident cases. The annual number of newly diagnosed female breast cancer was compared between the NHIS data and Korea National Cancer Incidence Database (KNCIDB). The annual treatment patterns including surgery, chemotherapy, radiation therapy, endocrine therapy and targeted therapy were analyzed.ResultsA total of 148,322 women with newly diagnosed invasive breast cancer during 2006–2014 was identified. The numbers of newly diagnosed invasive breast cancer cases were similar between the NHIS data and KNCIDB, which demonstrated a strong correlation (r = 0.995; P < 0.001). The age distribution of the breast cancer cases in the NHIS data and KNCIDB also showed a strong correlation (r = 1.000; P < 0.001). About 85% of newly diagnosed breast cancer patients underwent operations. Although the proportions of chemotherapy use have not changed during 2006–2014, the total number of chemotherapy prescriptions sharply increased during this period. The proportions of radiotherapy and anti-hormonal therapy increased. Among the anti-hormonal agents, tamoxifen was the most frequently prescribed medication, and letrozole was the most preferred endocrine treatment in patients aged ≥ 50 years.ConclusionAlong with the increased breast cancer incidence in Korea, the frequencies of breast cancer treatments have increased. The NHIS data can be a feasible data source for future research.

Endoscopic Treatment for Esophageal Cancer

Esophageal cancer incidence rate per 100,000 is 4.7 in 2013, which accounts for 1.1% of the total cancer incidence in Korea. Superficial esophageal squamous cell carcinoma is frequently detected in persons undergoing upper endoscopy for gastrointestinal symptoms or for gastric cancer screening. Esophagectomy with lymph node dissection is the standard treatment for esophageal cancer. However, given the considerable morbidity and mortality of esophagectomy, endoscopic resection has become the standard of care for most cases of superficial esophageal squamous cell carcinoma without metastasis. In addition, endoscopic submucosal dissection has increased the cure rate, even when the tumor is large, compared to endoscopic mucosal resection. Thus, endoscopic submucosal dissection is the treatment of choice for superficial esophageal squamous cell carcinoma with a negligible risk of lymph node metastasis. Endoscopic resection is usually associated with a low risk of morbidity and no mortality, and has also shown favorable long-term outcomes. However, the long-term risk of metastasis remains after endoscopic resection, which varies according to the characteristics of tumor. This review describes the indication and outcomes of endoscopic resection, complications of endoscopic resection, and management after treatment.

Incidence of Cerebral Palsy in Korea and the Effect of Socioeconomic Status: A Population-Based Nationwide Study.

PurposeCerebral palsy (CP) is a neurodevelopmental disorder that causes serious disability. Prematurity and low birth weight (LBW) are known to be the strongest risk factors of CP. While socioeconomic status (SES) has been found to influence the occurrence of CP, prematurity, and LBW, no studies have investigated this effect in Korea. The aim of this study was to evaluate the incidence of CP, prematurity, and LBW in Korea, as well as the effect of SES thereon.Materials and MethodsData were obtained from the National Health Information Database from 2007 to 2013; persons with a history of CP, prematurity, and LBW were investigated by year. SES was defined in accordance with income quintiles, birth regions, and coverage classification.ResultsThe incidence of CP decreased over the last five years, despite increased rates of prematurity and LBW. CP incidence was significantly lower in affluent groups than in the most deprived group, although this difference disappeared after controlling for confounders. The incidence of CP was significantly higher in medical aid beneficiaries, even after controlling for confounders.ConclusionCP incidence in Korea has decreased over the last five years, despite an increase in high-risk deliveries. Income level had no effect in CP incidence. These results may aid CP management and prevention policies.

Effects of Timely Control Intervention on the Spread of Middle East Respiratory Syndrome Coronavirus Infection.

ObjectivesThe 2015 Middle East Respiratory Syndrome Coronavirus (MERS-CoV) outbreak in Korea caused major economic and social problems. The control intervention was conducted during the MERS-CoV outbreak in Korea immediately after the confirmation of the index case. This study investigates whether the early risk communication with the general public and mass media is an effective preventive strategy.MethodsThe SEIR (Susceptible, Exposed, Infectious, Recovered) model with estimated parameters for the time series data of the daily MERS-CoV incidence in Korea was considered from May to December 2015. For 10,000 stochastic simulations, the SEIR model was computed using the Gillespie algorithm. Depending on the time of control intervention on the 20th, 40th, and 60th days after the identification of the index case, the box plots of MERS-CoV incidences in Korea were computed, and the results were analyzed via ANOVA.ResultsThe box plots showed that there was a significant difference between the non-intervention and intervention groups (the 20th day, 40th day, and 60th day groups) and seemed to show no significant difference based on the time of intervention. However, the ANOVA revealed that early intervention was a good strategy to control the disease.ConclusionAppropriate risk communication can secure the confidence of the general public in the public health authorities.

Unprocessed Meat Consumption and Incident Cardiovascular Diseases in Korean Adults: The Korean Genome and Epidemiology Study (KoGES)

Meat consumption has been shown to be associated with cardiovascular disease (CVD) risk in Western societies; however, epidemiological data are limited on the Korean population. Therefore, we examined the associations between unprocessed meat consumption and CVD incidence in Korea. Data were derived from the Ansung-Ansan cohort (2001–2012), including 9370 adults (40–69 years) without CVD or cancer at baseline. Total unprocessed meat consumption was estimated as the sum of unprocessed red meat (beef, pork, and organ meat) and poultry consumption. In the fully adjusted Cox regression model, the relative risks of CVD across increasing quintiles of total unprocessed meat intake were 1.0 (reference), 0.72 (95% confidence interval (CI): 0.55, 0.95), 0.57 (95% CI: 0.42, 0.78), 0.69 (95% CI: 0.51, 0.95), and 0.69 (95% CI: 0.48, 0.97), but no significant linear trend was detected (p for trend = 0.14). Frequent poultry consumption was significantly associated with a decreased CVD risk; this association showed a dose-response relationship (p for trend = 0.04). This study showed that a moderate intake of total unprocessed meat was inversely associated with CVD risk. A significant inverse association between poultry consumption and incident CVD was observed in Korean adults, requiring further confirmation in other populations.

242 Recent trends of skin cancer incidence in Korea from 2006 to 2015: A nation-wide population-based cohort study

242 Recent trends of skin cancer incidence in Korea from 2006 to 2015: A nation-wide population-based cohort study

Inference about Hazardous Clusters of Varicella Incidence in Korea: Using SaTScan and ArcGIS

Inference about Hazardous Clusters of Varicella Incidence in Korea: Using SaTScan and ArcGIS

Lung Cancer Risk and Residential Exposure to Air Pollution: A Korean Population-Based Case-Control Study.

PurposeTo investigate the association between long-term exposure to ambient air pollution and lung cancer incidence in Koreans.Materials and MethodsThis was a population-based case-control study covering 908 lung cancer patients and 908 controls selected from a random sample of people within each Korean province and matched according to age, sex, and smoking status. We developed land-use regression models to estimate annual residential exposure to particulate matter (PM10) and nitrogen dioxide (NO2) over a 20-year exposure period. Logistic regression was used to estimate odds ratios (ORs) and their corresponding 95% confidence intervals (CI).ResultsIncreases in lung cancer incidence (expressed as adjusted OR) were 1.09 (95% CI: 0.96−1.23) with a ten-unit increase in PM10 (µg/m3) and 1.10 (95% CI: 1.00−1.22) with a ten-unit increase in NO2 (ppb). Tendencies for stronger associations between air pollution and lung cancer incidence were noted among never smokers, among those with low fruit consumption, and among those with a higher education level. Air pollution was more strongly associated with squamous cell and small cell carcinomas than with adenocarcinoma of the lung.ConclusionThis study provides evidence that PM10 and NO2 contribute to lung cancer incidence in Korea.

Descriptive Epidemiology of Patients Undergoing Total Hip Arthroplasty in Korea with Focus on Incidence of Femoroacetabular Impingement: Single Center Study.

We analyzed the causes leading to total hip arthroplasty (THA), aimed to clarify the incidence of femoroacetabular impingement (FAI) among the causes, and compared the incidence in Korea with those in other countries. From January 2000 to December 2014, 1,206 hips of 818 patients who underwent primary THA at our institute were reviewed retrospectively in terms of radiographs and electronic charts. The radiographs and radiographic parameters were reviewed and measured by 2 of the authors, who are orthopedic surgeons. Patients were categorized in terms of the causes leading to THA as primary osteoarthritis (OA), rheumatoid arthritis (RA), posttraumatic arthritis, post infectious arthritis, avascular necrosis (AVN) of the femoral head, fracture of the femoral head or neck, ankylosing spondylitis (AS), developmental dysplasia of the hip (DDH), Legg-Calvé-Perthes disease (LCPD), FAI, and others. There were 32 patients (3.91%) in the primary OA group, 41 (5.01%) in the RA group, 84 (10.27%) in the posttraumatic arthritis group, 39 (4.77%) in the post infectious arthritis group, 365 (44.62%) in the AVN group, 39 (4.77%) in the fracture group, 21 (2.57%) in the AS group, 52 (6.36%) in the DDH group, 71 (8.68%) in the LCPD group, 52 (6.36%) in the FAI group, and 22 (2.69%) in the ‘other’ group. The causes leading to THA in Korea differ from those in Western countries. FAI could be causes of severe secondary OA that requires THA in Korea, therefore symptomatic FAI should not be neglected.

Analysis of the Relationship between Body Mass Index and Breast Cancer Incidence in Korean Women

Purpose Obesity in women has been shown to have correlation with breast cancer incidence. The proportion of Korean women who are obese has increased recently. However, there is no large-scale study evaluating the relationship between obesity and breast cancer incidence in Korea. In this study, we tried to identify the relationship between obesity and breast cancer incidence in Korean women by using body mass index (BMI) Methods A retrospective analysis was performed using single-center data of 28,631 patients screened with breast ultrasonography or mammography between January 2009 to December 2013 in Seoul National University Hospital Healthcare System Gangnam Center. Their clinical characteristics were evaluated. The correlations between breast cancer incidence with BMI and other factors were analyzed using univariate and multivariate logistic regression models. Results A total of 28,631 patients were enrolled; 67 patients were diagnosed with breast cancer. Among patients without breast cancer, the proportion of patients with BMI under 23 was 68.1%, whereas it was 56.7% among patients with breast cancer (p=0.036). In univariate analysis, patients with a BMI over 25 had an odds ratio of 2.09 for breast cancer compared with those with a BMI under 23 (p=0.012). In addition, patients with a waist circumference over 85 cm had an odds ratio of 1.69 for breast cancer compared with the others (p=0.042). In multivariate analysis, BMI also had significant correlation with breast cancer incidence (odds ratio=1.87, p=0.035). Conclusion An increase in BMI has positive correlation with breast cancer incidence in Korean women. However, a multi-centered prospective study is needed for further evaluation. Keywords: Body mass index; Breast neoplasms; Incidence; Korea

Increasing Incidence of Chronic Lymphocytic Leukemia in Korea, 1999-2010: Comparison to Plasma Cell Myeloma

Introduction: Chronic lymphocytic leukemia (CLL) and plasma cell myeloma (PCM) have markedly higher incidences in Western compared with Asian countries. In Asian countries, both CLL and PCM have increased over the previous few decades. However, the epidemiologic characteristics of CLL have not been previously studied in Korea. To track the changing trends in the incidence of CLL and PCM, we investigated epidemiologic data in Korea from 1999 to 2010 and compared it with data regarding Taiwanese and Caucasian Americans. We specifically addressed the differences in the trends of CLL and PCM.Methods: We included patients diagnosed with CLL or PCM between 1999 and 2010 from the KCCR and between 1992 and 2010 from the SEER database. We utilized the International Classification of Diseases for Oncology 3rd edition (ICD-O-3) codes for CLL (9823/3) and PCM (9732/3). The age at diagnosis was classified into 18 age groups by 5-year intervals. The data of Taiwan was obtained by personal communication.Results: The ASR of CLL from 1999 to 2010 in Korea was 0.13/100,000 person-years (0.17/100,000 for men and 0.09/100,000 for women). The APC in the CLL incidence in Korea was 4.17% (95% CI: 0.77-7.68%) (Table 1). For comparison, the ASR of the CLL in the US from 1999 to 2010 was 3.21/100,000, and CLL exhibited an APC of 0.68% (95% CI: -0.39 to 1.77%). The APC of CLL over the previous 12 years in Korea (4.17%) was markedly higher (i.e., 6.1-fold) compared with the US (0.68%). In a comparison of different ethnic groups, the ASR in Caucasians was 3.57/100,000; this incidence was the highest rate observed (Figure 1). The ASRs in individuals of African descent and Asians/Pacific Islanders were 2.41/100,000 and 0.74/100,000, respectively. The temporal trends in the ASRs in all races remained stable.The ASR of PCM for the period from 1999 to 2010 in Korea was 1.23/100,000 person-years (1.51/100,100 for men and 1.04/100,000 for women). The APC in the PCM incidence rates was 4.68% (95% CI: 4.12-5.24%) (Table 1). The ASR of PCM in the US from 1999 to 2010 was 3.97/100,000, which was 3.2-fold higher compared with Korea. The incidence of PCM in the US increased, with an APC of 0.50% (95% CI: 0.11-0.88%). The APC in Korea during the same period was 9.4-fold higher compared with the US. In the US, differences in the incidence were observed among ethnic groups, including Caucasians, African Americans and Asians or Pacific Islanders (Figure 1). African Americans constituted the group most susceptible to PCM, with an ASR of 8.42/100,000. The ASRs for Caucasian and Asians/Pacific Islanders were 3.67/100,000 and 2.37/100,000, respectively. The ASRs for the all races remained stable.Conclusion: In conclusion, the incidence rates of CLL have gradually increased from 1999 to 2010, while those of PCM have increased steeply. Both of them still show prominent lower incidences compared to US, but the incidence rates of CLL and PCM appears to be stable in the US. Though genetic background is the key factor for ethnic difference in the incidence, further study will be needed to elucidate the reason for recent differential increasing trends between CLL and PCM incidence in Korea.Table 1Comparison of incidence and trend in CLL and PCM during 1999-2010 between US and Korea°°°°USKoreaComparison (US/Korea)CLLASR*3.210.1324.69APC (95% CI)0.68(-0.39 to 1.77)4.17(0.77 to 7.68)¢"0.16PCMASR*3.971.233.23°°APC (95% CI)0.50(0.11 to 0.88)¢"4.68(4.12 to 5.24)¢"0.11* ASR are expressed per 100,000 person-years¢" APC is statistically significantly different from zeroAbbreviation: CLL, chronic lymphocytic leukemia; PCM, plasma cell myeloma; ASR, age-standardized rate; APC, annual percentage change; CI, confidence interval. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Stomach cancer incidence rates among Americans, Asian Americans and Native Asians from 1988 to 2011.

Stomach cancer is the second most common cancer in Eastern Asia, accounting for approximately 50% of all new cases of stomach cancer worldwide. Our objective was to compare the stomach cancer incidence rates of Asian Americans in Los Angeles with those of native Asians to assess the etiology of stomach cancer from 1988 to 2011. To examine these differences, Asian Americans (Korean, Japanese, Chinese, and Filipino Americans living in Los Angeles, California, USA) and native Asians (from Korea, Japan, China, and the Philippines) were selected for this study. Using the Cancer Incidence in Five Continents database, stomach cancer incidence rates were examined. Data from the National Cancer Registry of Korea were used for native Koreans. Between native countries, the incidence rates in Japan, China, the Philippines, and the US declined over time, but the incidence in Korea has remained constant. The incidences among Asian immigrants were lower than those among native Asians. The incidence rates of males were approximately 2 times higher than those among females in Asian countries were. The effect of immigration on stomach cancer incidence suggests that lifestyle factors are a significant determinant of stomach cancer risk. However, the incidence in Korea remains the highest of these countries

Protocol of a Thyroid Cancer Longitudinal Study (T-CALOS): a prospective, clinical and epidemiological study in Korea

IntroductionThyroid cancer incidence in Korea is the highest in the world and has recently increased steeply. However, factors contributing to this sudden increase have not been fully elucidated, and few...

History of Korean Thyroid Association and Recent Debates on Diagnosis and Treatment of Thyroid Cancer in Korea

It is an undeniable fact that the establishment of the Korean Thyroid Association (KTA) in 2008 will reinforce growing thyroidology in Korea. It is worthwhile to recall the histories behind the foundation of the KTA and to remember the efforts of the founders. Since 2005, there has been a massive increase in thyroid cancer incidence in Korea, which is much higher than in other countries. A large majority of cases fall into papillary microcarcinoma (less than 1 cm). Much debate has been sparked since early 2014 through mass media as well as among medical professionals on the issues of early screening and detection of small thyroid cancer, overdiagnosis and overtreatment of thyroid cancer. Based on the author's past 30 years of clinical practice in endocrinology with a focus on thyroid disease, this article presents my opinion on such debate and provides thoughts on future directions. This article only represents the author's personal, possibly limited, perspective thought. For this reason, readers are recommended to use their own judgement in weighing the opinions.

Recent Advances in Understanding Colorectal Cancer and Dysplasia Related to Ulcerative Colitis

Ulcerative colitis is an idiopathic chronic inflammatory bowel disease and its incidence in Korea has rapidly increased over the past two decades. Since ulcerative colitis is associated with increased risk for colorectal cancer, annual or biannual colonoscopy with four quadrant random biopsies at every 10 cm segments has been recommended for surveillance of colitic cancer in patients with long standing left-sided or extensive colitis. Recent epidemiologic data and meta-analysis suggest that the increment of colorectal cancer risk in ulcerative colitis was not larger than that of previous studies. Moreover, in addition to the extent and duration of colitis, other risk factors such as family history of colorectal cancer, primary sclerosing cholangitis, stricture, pseudopolyps, and histologic severity of inflammation have been recognized. As a result, updated guidelines provide surveillance strategies adjusted to the individual patient's risk for colitic cancer. Regarding surveillance method, target biopsy under panchromoendoscopy is preferentially recommended rather than random biopsy.

Age-Period-Cohort Analysis of Thyroid Cancer Incidence in Korea.

PurposeSouth Korea has the highest incidence rate of thyroid cancer in the world, and the incidence rate continues to increase. The aim of this study was to determine the age-period-cohort effects on the incidence of thyroid cancer in Korea.Materials and MethodsUsing the Korean National Cancer registry database, age-standardized incidence rates and annual percent changes (APCs) in thyroid cancer according to sex and histologic type were analyzed between 1997 and 2011. Age-period-cohort models were applied using an intrinsic estimator method according to sex.ResultsIn both men and women, the incidence of thyroid cancer showed a sharp increase from 1997 through 2011. Among the histologic types, papillary carcinoma showed the greatest increase, with APCs of 25.1% (95% confidence interval [CI], 22.7% to 27.5%) in men and 23.7% (95% CI, 21.9% to 25.5%) in women, whereas anaplastic carcinoma did not show a significant increase in either sex. An increase in overall thyroid cancer incidence over time was observed in all birth cohorts. An age-period-cohort model indicated a steeply increasing period effect, which increased prominently from 1997 to 2011 in both men and women. The age effect showed an inverted U-shaped trend. The cohort effect tended to show a slight increase or remain constant from 1952 to 1977, followed by a decrease.ConclusionThe period effect can explain the sharp increase in thyroid cancer incidence, strongly suggesting the role of thyroid screening.