Second malignant neoplasms after childhood cancer: A nationwide population-based study in Korea.

BACKGROUND: Second malignant neoplasm is one of the most devastating late effects of childhood cancers. This study aimed to evaluate the incidence and survival outcomes of patients developing second malignant neoplasms (SMNs) after surviving childhood cancer in Korea. METHODS: Medical data of childhood cancer patients diagnosed between 1993 and 2012 were obtained from the Korea Central Cancer Registry. The risk of developing SMNs was calculated using standardized incidence ratio (SIR), excess absolute risk (EAR), and cumulative risk. Kaplan-Meier survival curves were estimated, stratified by SMN status. RESULTS: A total of 28,405 childhood cancer patients were diagnosed in the study period, and 337 (1.2%) developed SMN. The total follow-up period was 197,359 person-years at risk (PYR), with a median follow-up duration of 5.6 years. Overall SIR was 20.0, which was 23.2 in women, and 17.6 in men. The overall EAR was 16.4 per 10,000 PYR. The most common types of SMNs, in order of incidence, were other malignant epithelial neoplasms, leukemia, and soft tissue sarcomas. The cumulative incidence of developing SMNs was 0.7% at 5 years, 1.2% at 10 years, and 2% at 15 years. After primary cancer diagnosis, the 10-year overall survival rate of patients with SMNs was 65.1%, which was lower than the 73.4% in patients without SMN. After SMN diagnosis, the 10-year overall survival rate was 55.8%. CONCLUSION: Through this registry-based study of 5.6 years of follow up, childhood cancer survivors were found to be at 20-fold higher risk of developing a malignant neoplasm compared to the general population. The majority of malignant neoplasms are malignant epithelial neoplasms, leukemia, and soft tissue sarcomas. Continued surveillance for assessing long-term risks, and guidance for appropriate long-term follow up of childhood cancer survivors, are needed.

Trends and Age-Period-Cohort Effects on the Incidence and Mortality Rate of Cervical Cancer in Korea.

PURPOSE: This study was conducted to describe the trends and age-period-cohort effects on the incidence and mortality rate of cervical cancer in Korea. MATERIALS AND METHODS: The incidence and mortality rate of cervical cancer among ≥ 20-year-old women from 1993 to 2012 were obtained from the Korea Central Cancer Registry and the Korean Statistical Information Service. Age-standardized rates were calculated and Joinpoint regression was used to evaluate the trends in the incidence and mortality rate. Age-period-cohort analysis was performed to investigate the independent effects of age, period and cohort. RESULTS: The incidence of cervical cancer decreased from 32.8 per 100,000 in 1993 to 15.9 per 100,000 in 2012 (annual percent change [APC], -3.9%; 95% confidence interval [CI], -4.2% to -3.6%). The mortality rate decreased from 5.2 per 100,000 in 1993 to 2.1 per 100,000 in 2012 (APC, -4.8%; 95% CI, -5.1% to -4.4%); however, the incidence and mortality rates among young women (< 30 years old) increased. An age-period-cohort model of the incidence and mortality rate showed decreasing period effects between 1993 and 2008 and decreasing cohort effects between 1928 and 1973, while birth cohorts after 1973 exhibited slight increases in the incidence and mortality rate of cervical cancer. CONCLUSION: Recent decreases in the incidence and mortality rate of cervical cancer were due to decreases in the period and cohort effects, which reflect the implementation of a cancer screening program and changes in lifestyle. However, our findings also highlighted an increase in cohort effects on the incidence and mortality rate among young women born after 1973.

Incidence and Survival of Childhood Cancer in Korea.

PURPOSE: An epidemiologic study of childhood cancer would provide useful information on cancer etiology and development of management guidelines. MATERIALS AND METHODS: Data from the Korea National Cancer Incidence Database were used to examine the incidence and survival of cancer in patients aged 0-14 years. Patients were grouped according to the International Classification of Childhood Cancer, 3rd edition. Age-specific and age-standardized incidences per million and estimated annual percentage change (APC) were calculated by sex and age. Five-year relative survival was calculated for four periods from 1993 to 2011. RESULTS: The study comprised 15,113 patients with malignant neoplasms. Age-standardized incidence rates for all cancers were 134.9 per million children in 1999-2011 and 144.0 and 124.9 per million for males and females, respectively (M/F ratio, 1.2; p < 0.05). The highest incidences were observed for 'leukemias, myeloproliferative diseases, and myelodysplastic diseases' (group I) (46.4), 'central nervous system neoplasms' (group III) (18.3), and 'lymphomas and reticuloendothelial neoplasms' (group II) (13.4). Age-standardized incidence increased from 117.9 in 1999 to 155.3 in 2011, with an APC of 2.4% (95% confidence interval, 2.1 to 2.7). There was a significant increase of APC in 'neuroblastoma and other peripheral nervous cell tumors' (group IV) (5.6%) and 'other malignant epithelial neoplasms and malignant melanomas' (group XI) (5.6%). The 5-year relative survival rate for all childhood cancers improved significantly from 56.2% (1993-1995) to 78.2% (2007-2011) (males, 56.7% to 77.7%; females, 55.5% to 78.8%). CONCLUSION: This study provides reliable information on incidence and survival trends for childhood cancer in Korea.

Estimates of Radiation Doses and Cancer Risk from Food Intake in Korea.

The aim of this study was to estimate internal radiation doses and lifetime cancer risk from food ingestion. Radiation doses from food intake were calculated using the Korea National Health and Nutrition Examination Survey and the measured radioactivity of (134)Cs, (137)Cs, and (131)I from the Ministry of Food and Drug Safety in Korea. Total number of measured data was 8,496 (3,643 for agricultural products, 644 for livestock products, 43 for milk products, 3,193 for marine products, and 973 for processed food). Cancer risk was calculated by multiplying the estimated committed effective dose and the detriment adjusted nominal risk coefficients recommended by the International Commission on Radiation Protection. The lifetime committed effective doses from the daily diet are ranged 2.957-3.710 mSv. Excess lifetime cancer risks are 14.4-18.1, 0.4-0.5, and 1.8-2.3 per 100,000 for all solid cancers combined, thyroid cancer, and leukemia, respectively.

Cancer incidence and survival among adolescents and young adults in Korea.

BACKGROUND: In Korea, cancer is the third leading cause of death among adolescents and young adults (AYAs). However, cancer incidence and survival trends among AYAs (15-29 years) have never been studied in Korea. Therefore, this study aimed to investigate the incidence and relative survival rates and their trends among AYAs in Korea. MATERIALS AND METHODS: Cancer incidence data from 1999-2010 were obtained from the Korea Central Cancer Registry (KCCR). Each cancer was classified into subgroups according to the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) AYA site recode. Percent distributions, age-specific incidence rates, age-standardized incidence rates per million, and annual percent changes (APCs) were calculated for AYAs according to sex. Five-year relative survival rates were estimated for cases diagnosed between 1993 and 2010 and followed up to 2011. RESULTS: The age-standardized incidence rates of all cancers combined were 196.4 and 367.8 per million for males and females, respectively (male-to-female (M/F) ratio: 0.5). The age-standardized incidence rates increased from 208.7 per million in 1999 to 396.4 per million in 2010, and the APC was 6.3% (P<0.001). The five most common cancers among AYAs were thyroid carcinoma, non-Hodgkin lymphoma, stomach carcinoma, breast carcinoma, and acute myeloid leukemia. In males, the 5-year relative survival rate improved, from 46.5% in 1993-1995 to 75.9% in 2006-2010. In females, the 5-year relative survival rate also improved, from 66.7% in 1993-1995 to 89.1% in 2006-2010. CONCLUSIONS: Our study showed increases in cancer incidence and improvements in the 5-year relative survival rate among Korean AYAs. This study also provides additional data regarding temporal and geographic trends in cancer that may enhance future efforts to identify factors affecting cancer incidence and responses to treatment among AYAs.

Incidence of cervical, endometrial, and ovarian cancer in Korea, 1999-2010.

OBJECTIVE: To investigate the recent incidence of and trends in cervical, endometrial, and ovarian cancer in Korean females. METHODS: Data from the Korea Central Cancer Registry between 1999 and 2010 were analyzed. Age-standardized rates (ASRs) and annual percent changes (APCs) were calculated. RESULTS: THE ABSOLUTE INCIDENCE RATES OF THE THREE MAJOR GYNECOLOGIC CANCERS INCREASED: 6,394 in 1999 to 7,454 in 2010. The ASR for gynecologic cancer was 23.7 per 100,000 in 1999 and decreased to 21.0 in 2010 (APC, -1.1%; 95% confidence interval [CI], -1.53 to -0.70) due to a definitive decrease in the incidence of cervical cancer (APC, -4.3%). Endometrial cancer has been definitively increasing (APC, 6.9% during 1999-2010), especially in females <30 years old (APC, 11.2%) and in females ≥80 years old (APC, 9.5%). The incidence of ovarian cancer is increasing gradually (APC, 1.5%). CONCLUSION: ASRs and APC for gynecologic cancers overall are decreasing due to the decrease in the incidence of cervical cancer. However, the incidence of endometrial and ovarian cancer has been increasing.

Variations of lung cancer risk from asbestos exposure: impact on estimation of population attributable fraction.

The purpose of this study is to investigate the potential impact of differing lung cancer risks in study populations on estimating population attributable fraction (PAF) from asbestos exposure. Studies were identified via a MEDLINE search up to September 2009 and from the reference lists of publications about asbestos exposure and lung cancer risk. Relative risk estimates were extracted from 160 studies and meta-relative risks were calculated according to random-effect models. Hypothetical PAFs were calculated based on the meta results and on the difference exposure scenarios. The risks for lung cancer from asbestos exposure were variable according to the region as well as other study characteristics. The risk estimates proved higher in Asian countries (RR=3.53), in studies with 500 or fewer subjects (RR=2.26), and papers published in the 1990s or earlier (RR=1.91), than did those for European or North American countries, studies with more than 500 subjects, and papers published in the 2000s, respectively. The differences in PAFs between Asian and North American studies were 15.5%, 30.3%, and 36.2% when the exposure prevalence was 10%, 30%, and 50%, respectively. This study suggested that it is important to apply appropriate lung cancer estimates to each study population when calculating PAF from asbestos exposure.

Paraquat application and respiratory health effects among South Korean farmers.

OBJECTIVES: Paraquat is commonly used worldwide as major herbicide. The objective of this study was to investigate the association among farmers between occupational paraquat exposure and respiratory health effects. METHODS: A cross-sectional survey of health effects related to an oil spill was conducted in South Korea from 2008 to 2009. For this analysis, a total of 2882 full-time farmers were selected from the overall sample. Data collection included an interviewer-administered questionnaire and spirometry testing. Logistic regression analysis and linear regression analysis were performed to evaluate the relationship between paraquat exposure and respiratory health outcomes after adjustment for potential confounders. RESULTS: The risks of self-reported physician-diagnosed asthma, chronic obstructive pulmonary disease and allergic rhinitis were non-significantly increased among paraquat-applying farmers compared with non-paraquat-applying farmers. Although the results of a pulmonary function test fell within normal limits, a decline in forced vital capacity and forced expiratory volume in one second was apparent among paraquat-applying farmers compared with non-paraquat-applying farmers. Forced vital capacity (ß = -5.20, p<0.001) and forced expiratory volume in one second (ß = -1.89, p = 0.010) significantly decreased with each unit increase in years of paraquat application. Paraquat-applying farmers showed a significant exposure-response relationship between restrictive ventilatory defects and paraquat application years (p trend = 0.015) or lifetime days of application (p trend = 0.007). CONCLUSIONS: Our findings suggest a possible association between paraquat application and adverse respiratory health effects among farmers.

Childhood cancer mortality and birth characteristics in Korea: a national population-based birth cohort study.

To examine the relationship between birth characteristics and childhood cancer mortality, a retrospective cohort study of Korean children was conducted using data collected by the national birth register between 1995 and 2006, which were then individually linked to death data. A cohort of 6,479,406 children was followed from birth until their death or until December 31, 2006. Poisson regression analyses were used to calculate rate ratios of childhood cancer deaths according to birth characteristics. A total of 1,469 cancer deaths were noted and the childhood cancer mortality rate was found to be 3.43 per 100,000 person-years in Korea during the period of 1995-2006. The birth characteristics examined in this study (i.e. , birth weight, gestational age, multiple births, parental ages, and number of siblings) were generally found to be not significantly associated with childhood cancer mortality, and the associations did not vary meaningfully with gender nor with cancer sites. However, among children aged 5-11 yr, higher birth weight was associated with elevated childhood cancer mortality (rate ratio = 1.28, 95% confidence interval 1.04-1.58). Our results offer no overall associations between childhood cancer mortality and birth characteristics, but suggest that the association may be specific to age group.

[Reliability of self-reported information by farmers on pesticide use].

OBJECTIVES: Exposure assessment is a major challenge faced by studies that evaluate the association between pesticide exposure and adverse health outcomes. The objective of this study was to investigate the reliability of information that farmers self-report regarding their pesticide use. METHODS: Twenty five items based upon existing questionnaires were designed to focus on pesticide exposure. In 2009 a self-administrated survey was conducted on two occasions four weeks apart among 205 farmers residing in Gyeonggi and Gangwon provinces. For a reliability measure, we calculated the percentage agreement, the kappa statistics and the intraclass correlation coefficient (ICC) between the two reports according to the characteristics of the subjects. RESULTS: Agreement for ever-never use of any pesticide was 96.4% (kappa 0.61). For both 'years used' and 'age at the first use' of overall pesticides, high agreement was obtained (ICC: 0.88 and, 0.78, respectively), whereas those of 'days used' and 'hours used' were relatively low (ICC: 0.42 and, 0.66, respectively). The kappa value for the use of personal protective equipment ranged from 0.46 to 0.59, and hygiene activities came out at 0.19 to 0.37. The agreement for individual pesticide use ranged widely and there was relatively low agreement due to the low response rates. The reliability scores did not significantly vary according to gender, age, the education level, the types of crop or the years of farming. CONCLUSIONS: Our results support that carefully designed, self-reported information on ever-never pesticide use among farmers is reliable. However, the reliability of data on individual pesticide exposure may be unstable due to low response rates and needs to be refined.

Childhood cancer mortality and socioeconomic position in South Korea: a national population-based birth cohort study.

OBJECTIVE: Cancer is among the leading causes of death in children, and the influence of socioeconomic inequalities on childhood cancer is an important public health concern. We examined the relationship of socioeconomic position with childhood cancer mortality in South Korea. METHODS: A retrospective cohort study of South Koreans was conducted using data from the national birth register collected between 1995 and 2006, which was individually linked to mortality data. A cohort of 6,479,406 children was followed from birth until their death or through December 31, 2006. Poisson regression analysis was used to estimate the rate ratios of childhood cancer death according to socioeconomic position. RESULTS: A total of 1,469 cancer deaths were observed during the study period. We found significantly increased cancer mortality to be associated with the educational level of mother (RR = 1.56, 95% CI 1.27-1.91) and father (RR = 1.39, 95% CI 1.15-1.70) in middle school graduate or below compared with those of college graduate or higher. The risks of cancer death increased among children born with fathers outside the workforce (RR = 1.36, 95% CI 1.09-1.69) and with mothers engaged in manual work (RR = 1.41, 95% CI 1.03-1.92), when compared with those of non-manual counterparts. Children born in rural areas showed significantly increased risk of death from cancer. CONCLUSIONS: We concluded that in South Korea, there were inequalities in childhood cancer mortality by socioeconomic position.

Disease prevalence and mortality among agricultural workers in Korea.

The aim of this paper was to provide an overview of mortality and disease prevalence related to occupational diseases among agricultural workers in Korea. We evaluated the age-standardized mortality rates and the prevalence of chronic diseases and compared them with those of other populations using death registration data from 2004 through 2008 and the 2005 Korean National Health and Nutrition Examination Survey. In addition, we conducted a literature review on published articles examining the health status of farmers in Korea. Agricultural workers have a significantly higher mortality of cancer, tuberculosis, chronic respiratory diseases, liver diseases, suicide, motor and non-motor vehicle accidents. Compared to other populations, farmers have higher prevalence rates of arthritis and intervertebral disc disorders. The literature review revealed a number of work-related diseases among farmers, such as musculoskeletal diseases, pesticide poisoning, infections, and respiratory and neurologic diseases. Korean farmers demonstrate a distinct pattern of mortality and disease prevalence compared to other populations. Although lifestyle factors remain important contributors to those deaths and diseases, our study suggests that occupation is a major determinant as well. Intensive programs such as surveillance systems, therefore, should be developed in order to identify and prevent work-related diseases among agricultural workers in Korea.

Prevalence and changes in chronic diseases among South Korean farmers: 1998 to 2005.

BACKGROUND: Epidemiologic studies have suggested a unique pattern of disease among farmers in Western countries, but limited information is available about the magnitude of disease prevalence and their changes over time in Asian farmers. The aim of this study was to compare the prevalence and changes in chronic diseases among farmers with those of other occupational groups in South Korea. METHODS: Using data from three consecutive cross-sectional national surveys: the Korean National Health and Nutrition Examination Survey 1998 (n = 39,060), 2001 (n = 37,769), and 2005 (n = 34,145), we calculated age and gender-standardized prevalence of chronic diseases by the direct method and compared the prevalence changes from 1998 to 2005. RESULTS: Female farmers had significantly higher chronic disease prevalence than other occupational groups in all three surveys. Arthritis was the most prevalent chronic disease among farmers for both men and women. Compared with other populations, farmers demonstrated a higher prevalence of arthritis and intervertebral disc disorders. Farmers showed higher prevalence changes for intervertebral disc disorders than other occupational workers. CONCLUSION: Our findings support that South Korean farmers have a distinct pattern of diseases prevalence from other populations. More detailed studies investigating the risk of musculoskeletal diseases and intensive intervention efforts to reduce the prevalence these diseases, particularly among female farmers, are required.