Cancer survival in Seoul, Republic of Korea, 1993-1997

The Seoul cancer registry was established in 1991. Cancer is a notifiable disease, and registration of cases is done by passive and active methods. The registry contributed survival data for 56 cancer sites or types registered during 1993-1997. Follow-up information has been gleaned predominantly by passive methods with median follow-up ranging between 5-82 months for various cancers. The proportion with histologically verified diagnosis for different cancers ranged between 23-99%; death certificates only (DCOs) comprised 0-67%; 33-100% of total registered cases were included for survival analysis. The top-ranking cancers on 5-year age-standardized relative survival rates were testis and placenta (95%), thyroid (93%), non-melanoma skin (93%), corpus uteri (79%), renal pelvis (77%), cervix (76%), Hodgkin lymphoma (75%), breast (74%) and prostate (74%). Five-year relative survival by age group showed a decreasing trend with increasing age groups for cancers of the small intestine, colon, gall bladder, cervix, corpus uteri, ovary, kidney, urinary bladder and thyroid, or was fluctuating for other cancers.

Meta- and pooled analyses of the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and colorectal cancer: a HuGE-GSEC review

Worldwide, over 1 million cases of colorectal cancer (CRC) were reported in 2002, with a 50% mortality rate, making CRC the second most common cancer in adults. Certain racial/ethnic populations continue to experience a disproportionate burden of CRC. A common polymorphism in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been associated with a lower risk of CRC. The authors performed both a meta-analysis (29 studies; 11,936 cases, 18,714 controls) and a pooled analysis (14 studies; 5,068 cases, 7,876 controls) of the C677T MTHFR polymorphism and CRC, with stratification by racial/ethnic population and behavioral risk factors. There were few studies on different racial/ethnic populations. The overall meta-analysis odds ratio for CRC for persons with the TT genotype was 0.83 (95% confidence interval (CI): 0.77, 0.90). An inverse association was observed in whites (odds ratio = 0.83, 95% CI: 0.74, 0.94) and Asians (odds ratio = 0.80, 95% CI: 0.67, 0.96) but not in Latinos or blacks. Similar results were observed for Asians, Latinos, and blacks in the pooled analysis. The inverse association between the MTHFR 677TT polymorphism and CRC was not significantly modified by smoking status or body mass index; however, it was present in regular alcohol users only. The MTHFR 677TT polymorphism seems to be associated with a reduced risk of CRC, but this may not hold true for all populations.

Prevalences of symptoms of asthma and other allergic diseases in korean children: a nationwide questionnaire survey

The purpose of this study was to estimate the national prevalence of childhood asthma and other allergic diseases in Korea, and to determine potential risk factors for the diseases. Stratified random samples of 42,886 were selected from 34 elementary (6-12 yr olds) and 34 middle schools (12-15 yr olds) nationwide, and 38,955 were in the final analysis. The Korean-translated modified version of the International Study of Asthma and Allergies in Childhood questionnaire was used in this cross-sectional survey. Twelve-month prevalences of the symptoms of asthma, rhinoconjunctivitis, and flexural eczema were 8.7%, 10.5%, 7.3% in 6-12 yr olds, and 8.2%, 10.0%, 3.9% in 12-15 yr olds, respectively. For allergic conjunctivitis, food allergy, and drug allergy, the prevalences in 6-12 yr olds were 11.2%, 6.5%, and 1.5%, respectively. Asthma and flexural eczema decreased significantly with age. Other significant risk factors were also noted. For 6-12 yr-old asthma, adjusted odds ratio (aOR) of body mass index was 1.21 with 95% confidence interval (CI) 1.0-1.48, aOR of passive smoking was 1.37 with 95%CI 1.24-1.51, aOR of carpet use was 1.28 with 95%CI 1.10-1.49. For 6-12 yr-old eczema, aOR of affluence was 1.22 with 95%CI 1.07-1.39. The control of obesity and passive smoking would be the most important preventive measures of allergic diseases.

Incidence pattern of colorectal cancer in Korea by subsite of origin

It has been suggested that colorectal cancer might not be one homogenous disease entity, based on the distinctive characteristics of its subsite of origin. Incidence data on 4,987 colorectal cancer were obtained from the Seoul Cancer Registry between 1993 and 1995. Age, sex, and subsite-specific incidence rates were compared. The age-standardized annual incidence rates of total colorectal cancer were 26.1 and 18.0 per 100,000 for men and women, respectively. There were no appreciable difference in the rates of colon and rectal cancer for either sex (colon vs rectum: 12.8 vs. 13.2 for men, 9.3 vs. 8.6 for women). The incidence rate of right colon was slightly higher in men than in women, and this discrepancy became even greater in left colon (men vs women: 3.5 vs. 3.0 for right colon, 4.7 vs. 2.9 for left colon). When the incidence rate of right colon was compared with that of left colon, women had a higher rate in the right colon among the elderly, aged 60 yr and over and a lower rate at age 40 yr or less, while the opposite was observed for men. More analytic approaches are needed to identify which factors are related with these descriptive results in colorectal cancer incidence.

Vegetables, cereals and colon cancer mortality: long-term trend in Japan

Vegetables, cereals and meat are foods of interest in the aetiology of colon cancer. While vegetable consumption is considered to be protective against colon cancer, the role of cereals in colon carcinogenesis remains controversial. Colon cancer mortality has rapidly increased in Japan since the 1950s. We examined the trend of consumption of vegetables, cereals and meat in Japan during the period from 1950 to 1995. Vegetable consumption has been almost constant during the period, whereas cereal consumption has declined drastically. Meat consumption increased up until the 1970s, but the increase has been minimal thereafter. These consumption patterns suggest that cereals are an important dietary factor determining the risk of colon cancer in Japan.

Factors associated with positive predictability of the anti-HCV ELISA method with confirmatory RT-PCR

The positive predictability of anti-HCV ELISA is low, especially, in blood donors and in healthy populations. False positive anti-HCV results pose some difficulties in medical practice and in blood screening. The aim of this study was to identify the factors associated with true hepatitis C virus (HCV) infection among anti-HCV ELISA-positives. A case-control analysis was conducted using 354 subjects who were positive for anti-HCV ELISA. All subjects were tested for true HCV infection using the reverse transcriptase polymerase chain reaction (RT-PCR). Tests for serum alanine aminotransferase (ALT), fasting glucose, HBsAg, anti-HBc antibody, alpha-fetoprotein, platelet count and ultrasound of liver were also performed. Epidemiological data were obtained by self-administered questionnaires. Out of 354 subjects, 202 (57.1%) were positive for HCV by RT-PCR and 152 were negative and used as the control group. In multivariate analysis, blood transfusion (odds ratio, OR 2.3, 95% confidence interval, CI 1.3-4.0), elevated ALT (OR 2.2, 95% CI 1.2-4.3) and higher anti-HCV ELISA ratios (more than 3; OR 1.7, 95% CI 1.3-2.1) were associated with true HCV infection. Thrombocytopenia was also associated with the presence of HCV in univariate analysis. These results suggest that a history of blood transfusion, elevated ALT and a high score on anti-HCV ELISA ratios are associated with true HCV infection among anti-HCV ELISA-positives.

Evaluation of the completeness of cancer case ascertainment in the Seoul male cohort study: application of the capture-recapture method

Since the completeness of case ascertainment is directly related to the validity of a study, the evaluation of completeness is an essential feature of a cohort study. To estimate the completeness of cancer case ascertainment during a three year period (Jan. 1, 1993, to Dec. 31, 1995) in which the Seoul Male Cohort was followed up, we applied capture-recapture method. Data were obtained from the cancer registries, medical records and death certificates, with cases identified from each source numbering 103, 105, and 38, respectively. After eliminating duplicate cases, the total number was 141, and by using a log-linear model, the number of cases not detected by any of the three data sources was estimated to be 16. For all cancers, the estimated completeness of follow-up was 89.9%.

Prevalence and disease experience rates in Korean physicians

This study aimed to find out the morbid status of Korean physicians living in Korea, as one part of a feasibility study on the Korean physician cohort. It was performed by mail survey using a self-administered questionnaire from Jan. 1, 1995 through Dec. 31, 1995. Study subjects were 21,552 including 17,877 (81.1%) males and 3,384 (15.5%) females. Person based prevalence rate of disease was 17.7% (18.3% for males and 13.8% for females) with the rate increasing with age. The disease group showing the highest prevalence rate was circulatory diseases (5.16%) for males, and respiratory disease (3.13%) for females. The individual disease showing the highest prevalence rates was hypertension (3.77%) for males and allergic rhinitis (2.25%) for females. The person based disease experience rate was 36.2% (36.9% for males, 32.7% for females) with the rate increasing with age. The disease group showing the highest disease experience rate was digestive disease for both sexes (10.05% for males, 7.42% for females). Individual disease showing the highest disease experience rate was hypertension (5.00%) for males and allergic rhinitis (4.08%) for females. There were different ranks of both prevalence and disease experience rate depending on age in both sexes.

Lack of familial clustering of hepatitis C virus infection

BACKGROUND

Although transmission of hepatitis C virus (HCV) through parental exposure is well documented, it is still controversial whether familial clustering of HCV occurs.

METHODS

To investigate risk factors for HCV infection, 109 cases and 84 non-infected controls were studied. In addition, 250 family members (104 men, 146 women) of cases and 170 family members of controls (64 men, 106 women) were tested for HCV infection using an anti-HCV antibody, alanine aminotransferase (ALT), and reverse transcribed polymerase chain reaction (RT-PCR).

RESULTS

In the case-control analysis, people aged > or =60 were almost three times more likely to be infected by HCV than those aged <40. Risk of HCV infection was most strongly related to a history of blood transfusion (OR = 12.6, 95% CI: 4.3-36.5) followed by a history of jaundice (OR = 4.1, 95% CI: 1.3-12.6). Only one family member of cases and no-one related to the controls had HCV infection.

CONCLUSIONS

These results suggest that, in Korea, age and parenteral exposure, such as a blood transfusion, are risk factors for HCV infection and familial clustering of HCV infection, if it occurs, is rare.

Epidemiologic and clinical characteristics of migraine and tension-type headache in Korea

This is the first population-based epidemiologic study of chronic headache in South Korea. The diagnosis and classification of headache was according to the criteria of the International Headache Society. Sixty-eight percent of the studied population experienced headache during the preceding year. The estimated prevalences were 22.3% for migraine (male 20.2%, female 24.3%) and 16.2% for tension-type headache (male 17.8%, female 14.7%). In migraine, the 15- to 19-year age group showed maximal prevalence in both sexes (male 28.5%, female 34.7%). The prevalence of tension-type headache was highest in the 50- to 59-year age group in men (24.2%) and in the 20- to 29-year age group in women (20.2%). In migraine, headache intensity was more severe in women than in men, but in tension-type headache there was no difference in the severity of headache between the sexes. Phonophobia was the most common associated symptom of migraine (65.1%). In the migraine with aura group, the most common aura was visual disturbance, including scintillation and image distortion (82.3%). Only 24.4% of migraineurs and 12.3% of patients with tension-type headache had ever consulted a doctor for headache. The prevalence of migraine was not lower than in western countries and much higher than in previous studies conducted in other Asian countries.

Hepatitis B vaccination and reduced risk of primary liver cancer among male adults: a cohort study in Korea

BACKGROUND

Primary liver cancer is an important health problem in Korea, where hepatitis B virus (HBV) infection is prevalent. The authors conducted a prospective cohort study to evaluate the protective effect of HBV vaccination against liver cancer in adults.

METHODS

A total of 370,285 males aged > or = 30 comprised the study population. They were clinically free of liver diseases, and had not been vaccinated against HBV at enrolment. The results of HBV surface antigen (HBsAg) and antibody to HBsAg (anti-HBs) marker positivity and those of the vaccination programme which took place during 1985 were used for the construction of the cohort. About 5% (n = 18,914) were HBsAg positive, 78,094 were anti-HBs positive, and 273,277 were negative for both. Among the candidates for HBV vaccination (n = 273,277), 35,934 (13.2%) people had been vaccinated against HBV during 1985. Cases of liver cancer were ascertained by record linkage and from medical records covering 1986-1989. A multivariate log-linear model was used to test statistical significance and to estimate relative risks (RR).

RESULTS

The total follow-up period was 1,404,566 person-years, with an average of 3 years and 10 months. A total of 302 incident cases were ascertained. The overall incidence rate of liver cancer was 21.7 per 100,000 person-years. With reference to the incidence level among the unvaccinated and uninfected, the RR of primary liver cancer among the chronically infected and that of the unvaccinated and infected was 18.1 (95% CI: 14.2-22.9) and 0.34 (95% CI: 0.19-0.60), respectively. The RR among the vaccinated group was 0.58 (95% CI: 0.31-1.09).

CONCLUSIONS

This study suggested that artificial immunization through HBV vaccination, even in adulthood, reduces the risk of liver cancer. It might also offer a practicable means of primary prevention, especially in areas with hyperendemicity of HBV infection.

Comparison of Helicobacter pylori infection between Fukuoka, Japan and Chinju, Korea

BACKGROUND

Helicobacter pylori is the causative agent of type B chronic gastritis, and plays a major role in the pathogenesis of gastroduodenal ulcer and gastric cancer. Because gastric cancer has been the leading cause of cancer mortality in Japan and Korea, we conducted a seroepidemiological study to estimate the prevalence of H. pylori infection in Japan and Korea in order to explain the current change in the gastric cancer incidences between two countries.

MATERIALS AND METHODS

Samples used for this study included 1204 sera from Chinju, Korea and 580 sera from Fukuoka, Japan. Immunoblotting, using a sonicated crude H. pylori antigen and 1:5 dilution of serum, was performed, considering the immunoblot shows reactivity to the 120 Kd antigen of H. pylori as a specific marker of H. pylori infection.

RESULTS

Seroepidemiology data from Fukuoka, Japan showed a prevalence of H. pylori infection of 20% before school age, 40% by teenage years, and over 80% beyond 20 years of age. Seroepidemiology data from Chinju, Korea, showed a 50% infection rate in preschool ages, and over 80% prevalence rate after 7 years of age.

CONCLUSIONS

Lower rates of childhood H. pylori infection in Fukuoka may explain the recent decline and shift in the incidence of stomach cancer in Japan, supporting the hypothesis that H. pylori is a major determinant in the pathogenesis of stomach cancer.

Diet and stomach cancer in Korea

Stomach cancer is the most prevalent malignant neoplasm in Korea. As of 1991-1992 in Seoul, the cumulative rates reported for the age span 0-74 were 7.6% in males and 3.1% in females. A recent case-control study reported that several food items and cooking methods are associated with increased or decreased risk of stomach cancer among Koreans. An increased risk of stomach cancer was noted among people who frequently consume broiled meats and fishes, salted side dishes (salted/fermented fish products) and salty stewed foods, such as soybean paste thick stew. Frequent consumption of mung bean pancake, tofu, cabbage, spinach and sesame oil decreased the risk. Analysis by cooking method showed that risk of stomach cancer from the same foods varied with preparation. For meat and fish, pan frying was associated with decreased risk, whereas stewing or broiling was associated with increased risk. Pickled vegetables increased the risk, whereas fresh vegetables did not. In a recent cohort study in Seoul, green vegetables and soybean foods were associated with a decreased risk of stomach cancer. Case-control and cohort studies have reported that ginseng intake decreased the risk of gastric cancer.

Prevalence of childhood asthma based on questionnaires and methacholine bronchial provocation test in Korea

BACKGROUND

In most epidemiological survey studies, only subjective symptoms and past medical history of asthma have been used as diagnostic criteria. Even though a questionnaire survey can be performed in a large population study at low cost, limitations such as lack of objectivity and poor predictability in non-specific bronchial hyperresponsiveness cannot be avoided.

OBJECTIVES

The purpose of this study was to elucidate the prevalence of current asthma based on questionnaires and methacholine bronchial provocation test, and the prevalence of atopy in Korea.

METHODS

We performed modified ATS respiratory questionnaires and allergen skin-prick test with 10 common inhalant allergens among 3219 subjects aged 7-19 years in Seoul and a rural part of a small city, Chungju in Korea. Methacholine bronchial provocation tests were also performed among those who had asthma symptoms according to the questionnaire. The criteria of asthma was presence of both asthma symptoms and non-specific bronchial hyperresponsiveness. Atopy was defined as when an allergen induced weal size is same or larger than that caused by histamine.

RESULTS

The prevalence of asthma based on questionnaires and methacholine bronchial provocation tests was 4.6%, while the prevalence of wheeze was 8.2% and 19.3% of total population complained of one or more respiratory symptoms related to asthma on the questionnaires. There was no significant difference according to age, sex and living area. The mean prevalence of atopy was 35.0% and the most common allergens were Dermatophagoides farinae (30.9%), Dermatophagoides pteronyssinus (27.5%), cat fur (20.4%) and cockroach (11.8%). The atopy prevalence in Chungju area was higher than that in Seoul and males showed a higher prevalence than females. The asthma prevalence was higher among atopics (6.8%) than among non-atopics (2.7%). None of questionnaire items were enough to predict the presence of bronchial hyperresponsiveness in terms of sensitivity, specificity and positive predictive value.

CONCLUSION

The prevalence rate of current asthma in Korea was 4.6% and the prevalence rate of atopy in Korea was 35.0%. Questionnaire-based surveys are not enough to predict the actual prevalence of asthma.

Diet and stomach cancer in Korea

Stomach cancer is the most prevalent malignant neoplasm in Korea. As of 1991-1992 in Seoul, the cumulative rates reported for the age span 0-74 were 7.6% in males and 3.1% in females. A recent case-control study reported that several food items and cooking methods are associated with increased or decreased risk of stomach cancer among Koreans. An increased risk of stomach cancer was noted among people who frequently consume broiled meats and fishes, salted side dishes (salted/fermented fish products) and salty stewed foods, such as soybean paste thick stew. Frequent consumption of mung bean pancake, tofu, cabbage, spinach and sesame oil decreased the risk. Analysis by cooking method showed that risk of stomach cancer from the same foods varied with preparation. For meat and fish, pan frying was associated with decreased risk, whereas stewing or broiling was associated with increased risk. Pickled vegetables increased the risk, whereas fresh vegetables did not. In a recent cohort study in Seoul, green vegetables and soybean foods were associated with a decreased risk of stomach cancer. Case-control and cohort studies have reported that ginseng intake decreased the risk of gastric cancer.

Hepatitis B and C virus, Clonorchis sinensis for the risk of liver cancer: a case-control study in Pusan, Korea

BACKGROUND

Liver cancer mortality in Korea is the highest in the world. Hepatitis B and C viruses (HBV, HCV) are known to be the major risk factors of hepatocellular carcinoma (HCC). Cholangiocarcinoma (CLG) accounts for more than 20% of liver cancer in the Pusan area. In Korea, the different roles of known risk factors in the development of HCC or CLG have not been adequately evaluated.

METHODS

Case-control studies involved 203 incident HCC cases, 406 controls matched to the HCC cases for age (+/- 4 years) and sex, and 41 CLG cases (the HCC controls were used). They were carried out from August 1990 to August 1993.

RESULTS

Relative risk (RR) of HBsAg (87.4; 95% confidence interval [CI]: 22.2-344.3) and RR of anti-HCV positivity (30.3; 95% CI: 6.1-150.6) were significant for the risk of HCC after adjustment for potentially confounding factors. In contrast, RR of Clonorchis sinensis in stool (2.7; 95% CI: 1.1-6.3) and RR of heavy drinking (4.6; 95% CI: 1.4-15.2) were significant for the risk of CLG. Transfusion history, acupuncture history, and cigarette smoking were not associated with the risk of HCC or CLG.

CONCLUSIONS

Strong evidence indicated that both HBV and HCV infection were independent risk factors for HCC. In contrast, C. sinensis in stools and heavy drinking were associated with the risk of CLG in Korea.

Ethnic variation in the incidence of stomach cancer in Illinois, 1986-1988

Wide ethnic and geographic variation in stomach cancer incidence has been reported in Eastern and Western countries. Stomach cancer is reported to be the most common malignant neoplasm in Asia, specifically, China, Japan, and Korea. In contrast, stomach cancer incidence in the United States among Caucasians is low and among blacks, moderate to low. Only one other study has directly compared the rates of stomach cancer in the three ethnic groups (i.e., white, African American, and immigrant Korean) living in the same region. The authors extend their investigation by comparing the incidence rate of stomach cancer among the same three ethnic groups in the state of illinois from 1986 to 1988. In this study, the incidence of stomach cancer was observed to be lowest in whites, intermediate in African Americans, and highest in immigrant Koreans. The overall 3-year cumulative incidence rate from 1986 to 1988 was 62.6/100,000 (95% confidence interval (CI) 38.6-86.7), 28.2/100,000 (95% CI 25.7-31), and 22.5/100,000 (95% CI 21.5-23.5) for immigrant Koreans, African Americans, and whites, respectively. The 3-year age-adjusted cumulative incidence rate for immigrant Koreans (172/100,000) was approximately four-and eightfold higher than for African Americans (41/100,000) and whites (21/100,000). The incidence of stomach cancer increased as a function of age in both sexes. Although a higher rate was observed in males than in females, these rates were four-and eightfold higher in African Americans and immigrant Koreans, when compared with their white counterparts in both sexes. Despite a substantial reduction of stomach cancer incidence in the United States and other Western countries, it remains the most frequent malignancy in native and immigrant Koreans. The high rate of stomach cancer in immigrant Koreans compared with African Americans and white populations residing in Illinois indicates either a drastically disproportionate undercount of immigrant Koreans in the 1990 census or a profound genetic-environmental interaction.

A case-control study on the risk factors of hepatitis C virus infection among Koreans

In order to identify the risk factors for hepatitis C virus (HCV) infections, a case-control study was conducted from September 1993 to April 1994. HCV infection was confirmed by the second generation of recombinant immunoblot assay. Sixty-four cases and 128 controls matched for age and sex with a 1:2 ratio of cases to controls were enrolled. Exposure data were obtained from all participants by self-administered questionnaire and the odds ratios of possible risk factors of HCV infection analysed. Sixty-four cases consisted of forty-two patients with chronic hepatitis, nine with cirrhosis, one with hepatocellular carcinoma, and twelve with normal liver function. History of acute hepatitis (OR 3.9) and transfusion (OR 2.4) were associated with an increased risk of HCV infection. Operation, acupuncture, endoscopy, tooth extraction, tattooing, ear piercing, needle sharing and family history of hepatitis were not associated with an increased risk of HCV infection. In conclusion, transfusion remains the major route of transmission of HCV in Korea.

Strategy for vaccination against hepatitis B in areas with high endemicity: focus on Korea

Hepatitis B vaccination strategies may vary from country to country depending on hepatitis B virus (HBV) endemicity, predominant modes of infection, age of infection, and health care resources. In areas with high endemicity like Korea, transmission of virus from carrier mothers to infants during the perinatal period, and from other horizontal sources to infants and children, account for most cases of HBV infection. The consequences of HBV infection at an early age are serious, as more than 70% remain chronic carriers of the virus. These chronic carriers are the principal source of infection for other susceptible people, and are themselves at high risk of developing other serious diseases, such as chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Theoretically, therefore, routine infant immunisation supplemented with prenatal screening of pregnant women for HBsAg or HBeAg and mass immunisation of children is the appropriate strategy for control of hepatitis B in these countries. To prevent primary liver cancer associated with HBV infection, however, immunisation of adults at high risk would also be prudent. Mandatory vaccination of all neonates is recommended in highly endemic areas, together with hepatitis B immune globulin in babies born to HBsAg carrier mothers.

Nationwide incidence estimation of lung cancer in Korea

The aim of this paper is to estimate the nationwide incidence rate of lung cancer in Korea. The potential incident cases were identified by hospital visiting and mailing, based on the ICD-9 diagnostic codes on the claims as one of the following: ICD-9 162-165 (malignant neoplasms of the respiratory system), 212 (benign neoplasm), 231 (carcinoma in situ), 511 (pleurisy), or 195-199 (malignant neoplasms with uncoded sites) in beneficiaries data of the Korea Medical Insurance Corporation from January, 1988 to December, 1989. Thereafter, the identified cases were confirmed by an oncologist (Dr. DS Heo). When adjusted with age distribution of the Korean population based on the 1985 Population Census, the incidence rate was 22.3 per 100,000 in males (95% CI: 21.70-23.01) and 8.37 (95% CI: 7.97-8.78) in females in 1989. And the age-adjusted rate for the world population was 39.63 in males and 9.95 in females.

1991 cancer incidence in Seoul, Korea: results of the Implementation Study of the Seoul Cancer Registry

This article presents the results of the Implementation Study of the Seoul Cancer Registry, which started in July, 1991 as a population based cancer registry in Seoul, Korea. The completeness and validity of the registered data were evaluated using Mortality/Incidence ratio (M/I ratio), Histologically Verified Cases (HV%), Primary Site Uncertain (PSU%), and Age Unknown (Age UNK%). Owing to the additional active surveillance, the completeness of the data turned out to be fairly acceptable, except for the aged over 75(Mortality/Incidence ratio was over 100%). Eventhough the Seoul cancer registry(SCR) has further way to go in the completeness especially among elderly persons, the validity of SCR data was also acceptable in terms of HV%, PSU%, and Age UNK%. However, PSU% and Age UNK% might need to be further reduced to be comparable with other well established cancer registries. The age standardized incidence rates(ASR) of all cancers between July 1, 1991 and June 30, 1992 were 232.4/100,000 in males and 147.9/100,000 in females. The top five major sites of cancers in Seoul were the stomach, liver, lung, colo-rectum, and bladder in order in males, and the uterine cervix, stomach, breast, colo-rectum, and liver in females. Those 5 cancer sites comprised 68.9% and 64.7% of the total cancer incidence in males and females, respectively.

Dietary factors and stomach cancer: a case-control study in Korea

BACKGROUND

Stomach cancer is the most common cancer among Koreans. There is wide agreement that dietary factors are important in gastric carcinogenesis, but the role of many Korean food items remains unknown.

METHODS

A case-control investigation involving 213 incident cases of histologically confirmed stomach cancer and an equal number of controls, matched by age (within 2 years) and sex, was conducted from June 1990 to October 1991.

RESULTS

An increased risk of stomach cancer was noted among those with high consumption of stewed foods such as soybean paste stew and hot pepper-soybean stew, broiled fish, and those who liked salty food. However, mung bean pancake, tofu (soybean curd), cabbage, spinach, and sesame oil decreased the risk of stomach cancer. Stratified analysis by salt in combined foods, such as stewed foods and pickled vegetables, disclosed salt as being an important risk factor. Analysis of cooking methods showed that broiling and salting increased the risk of stomach cancer, but that frying tended to decrease the risk. These results suggest that the cooking method might modify the gastric carcinogenicity of foods. As non-dietary factors, smoking and a family history of stomach cancer increased the risk, but use of a refrigerator decreased the risk of cancer.

CONCLUSIONS

Heavy salt consumption and cooking methods like broiling and salting seem to play a major role in gastric carcinogenesis among Koreans.

Familial clustering of hepatitis B and C viruses in Korea

In order to evaluate the familial clustering of hepatitis B virus(HBV) and hepatitis C virus(HCV) infections and to elucidate the possible routes of HCV transmission among Korean adults with chronic liver disease, 137 household contacts of 51 chronic carriers of HBsAg and 111 household contacts of 38 controls, and 181 household contacts of 96 anti-HCV positives and 102 household contacts of 76 anti-HCV negatives were tested from July 1990 to March 1994. Of 71 non-vaccinated household contacts of HBsAg carriers, 10 gave positive result for HBsAg(14.1%), but none of the household contacts of the controls were positive for HBsAg(p < 0.05). Familial clustering of HBV infection was found, when the offspring of carriers and controls were compared. A significantly higher percentage of the offspring of carriers were positive for HBV infection(54.6% vs 15.4%, p < 0.05) with OR of 6.6(95% Cl; 1.3-34.5). No evidence of familial clustering of HCV infection was found with 2.2%(4/181) anti-HCV positivity among the household contacts of index cases, similar to 1.0%(1/102) among those of controls. History of acute hepatitis(OR 3.2), transfusion(OR 3.2), and acupuncture(OR 2.5) were associated with an increased risk of HCV infection. In conclusion, HBV has strong familial clustering whereas HCV does not in Korea.

Incidence estimation of female breast cancer among Koreans

The authors conducted a nationwide survey to estimate the incidence rates of female breast cancer among Korean women in 1990-1991. We identified potential breast cancer cases based on the claims sent by medical care institutions throughout Korea to the Korea Medical Insurance Corporation (KMIC) from January 1988 to December 1989, whose diagnoses in the claims included one of the following diagnostic codes; ICD-9 174-175 (malignant neoplasms of the breast), 217 (benign neoplasms of the breast), 610-611 (benign mammary dysplasia and other disorders of the breast), 233 (carcinoma in situ of the breast and genito-urinary system), or 195-199 (malignant neoplasms with uncoded sites). In order to collect the final diagnosis of the potential cases, abstracting medical records was performed through visiting or mailing an abstracting format to the corresponding medical institutions. Thereafter oncologists reviewed the abstracting formats and confirmed the incident cases of female breast cancer among the potential breast cancer cases. Using these data from the KMIC, the incidence patterns of female breast cancer among Korean women were estimated as of July 1, 1988 to June 30, 1989. The incidence rate of female breast cancer adjusted for the Korean population was estimated to be 9.9 (95% confidence interval: 9.5-10.4). The cumulative rates for the ages 0-64 and 0-74 were 0.85% and 1.0%, respectively. The standardized rate for the world population was 10.9, which was lower than those of any other Asian country including China and Japan in 1983-1987.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors associated with intrafamilial transmission of hepatitis B virus infection in Korea

Epidemiologic and serologic data on 137 household contacts of 51 chronic carriers of HBsAg and 111 household contacts of 38 controls who were negative for serologic markers of hepatitis B virus (HBV) were obtained from March 1990 to August 1991. Using this data, possible routes of intrafamilial transmission of hepatitis B virus among household contacts of chronic carriers of hepatitis B surface antigen (HBsAg) were evaluated and analyzed. The HBsAg prevalence among the household contacts of carriers was 14. 1% (95% CI 7.8-24.0) compared to 0.0% (95% CI 0.0-7.0) among those of controls (P < 0.01). The offspring of carriers showed significantly higher risk of HBV infection(relative risk; 6.6). Sharing of towels and handkerchieves, and drinking vessels was associated with an increased risk of HBV infection via intrafamilial transmission in Korea (relative risk 11.5 for towel and handkerchief, 12.1 for drinking vessels).

Prevalence of hepatitis C virus antibody among Korean adults

To estimate the prevalence of hepatitis C virus (HCV) infection among Korean adults and to present the putative route of HCV transmission among them, serum samples from 4917 adults older than 20 years of age were tested for antibody to HCV (anti-HCV), and histories of blood transfusion and other pertinent information were obtained by self-administered questionnaires. The overall prevalence of anti-HCV was 1.7%; prevalence was 1.4% in subjects with normal levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), 3.3% in those with slightly elevated and 5.9% in those with markedly elevated levels of the enzymes. The prevalence of anti-HCV increased with increasing age (P < 0.01), but was not associated with blood transfusion. The present study suggests that the prevalence of HCV infection was 1.4% and that the major routes of HCV transmission may be other than blood transfusion in healthy Korean adults.

Risk of gastric cancer among Korean familial adenomatous polyposis patients. Report of three cases

Gastric cancer has been recognized as an extracolonic manifestation in patients with familial adenomatous polyposis (FAP). In Korea, gastric cancer is the most common malignant neoplasm. In a recent survey, we collected data from 72 Korean patients with FAP. Among them, three (4.2 percent) were found to have associated gastric cancer. This incidence of gastric cancer in our series is much higher than the previous reports from Japan and other countries. The expected cumulative incidence of gastric cancer among these 72 patients was 0.44, which gives the standardized incidence ratio of 6.9 (95 percent CI, 1.4-20.1). This difference in incidence of gastric cancer was statistically significant (P less than 0.05), which implies that patients with FAP are at significantly higher risk of developing gastric cancer compared with the general population in Korea. These findings confirm an increased risk of gastric cancer in FAP patients, even in a region where gastric cancer is highly prevalent.

A reconstructed cohort study on the hepatitis B virus infection as a risk factor of liver cancer in Korea

A stable cohort (n = 369,725) was reconstructed to test the association of hepatitis B virus (HBV) infection with subsequent occurrence of liver cancer in a healthy Korean population. The cohort consisted of male beneficiaries of the Korea Medical Insurance Corporation over 30 years of age, living nationwide. The HBV infection was tested by the reversed passive hemagglutination method for the HBsAg and by the passive hemagglutination method for the anti-HBs at the time of recruitment in 1984. Admissions due to liver diseases were identified through a computerized system for reimbursements on medical insurance claims from January 1, 1985 to December 31, 1987. For a more valid estimate of incidence, a sample survey was carried out, obtaining correction coefficients against misclassification of the diagnosis, as well as those for duplicate claims in a year. The incidence rate of liver cancer steadily increased with age (kappa 2 TREND = 51.1, df = 1, p = 0.00).(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence estimation of leukemia among Koreans

This study was undertaken in order to estimate the incidence of leukemia among Koreans. Medical records were studied of patients with diagnoses of either ICD-9 038 (septicemia), or 204-208 (leukemias), or 284 (aplastic anemia), or 289 (other diseases of the blood and blood-forming organs) in the claims sent in by medical care institutions throughout the country to the Korea Medical Insurance Corporation (KMIC) during the period from January 1, 1986 to December 31, 1987. These records were abstracted in order to identify and confirm new cases of leukemia among the beneficiaries of KMIC, which covers about 10% of the whole Korean population. Using these data from the KMIC, the incidence rates of leukemia among Koreans were estimated as of July 1st, 1986 to June 30, 1987. The crude incidence rate of all types of leukemia among Koreans is estimated to be 3.45 (95% CI; 0.77-9.55) and 2.29 (95% CI; 0.28-7.81) per 100,000 in males and females, respectively. The cumulative rate for the age span 0-64 is 0.25% in males and 0.18% in females, and for the age span 0-74, 0.35% in males and 0.23% in females. The adjusted rates for the standard world population are 3.90 and 2.48 per 100,000 in males and females, respectively. The relative frequencies by type are 51.5% for AML, 21.6% for ALL, 20.2% for CML, and only 1.5% for CLL. The incidence patterns of various types of leukemia, of which this is the first report in Korea, are analyzed and presented.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence estimation of thyroid cancer among Koreans

The medical records of inpatients with diagnoses of either ICD-9 193(malignant neoplasm of the thyroid gland) or 226(benign neoplasm of the thyroid gland) in the claims sent in by medical care institutions throughout the country, to the Korea Medical Insurance Corporation (KMIC) during the period from January 1, 1986 to December 31, 1987 were abstracted. These records were abstracted in order to identify and confirm new cases of thyroid cancer among the beneficiaries of the KMIC. Using these data, the incidence rate of thyroid cancer among Koreans was estimated as of July 1, 1986 through June 30, 1987. The crude rates were estimated to be 0.76(95% Cl: 0.63-0.87) and 3.87(95% Cl: 3.60-4.14) per 100,000 in males and females, respectively, and the cumulative rates for the age spans 0-64 and 0-74 in males were 0.06% and 1.10%, respectively. In females, those were equally 0.35%. The age-adjusted rate for the world population was 0.93 per 100,000 in males, which is one of the lowest levels in the world. However, the adjusted rate in females was 3.96 per 100,000, which is an average level and very similar to that of the Chinese in Singapore and Shanghai. A similar tendency was shown in the case of the truncated rates for the age group of 35-64, which was 1.91 per 100,000 in males and 8.82 per 100,000 in females.

Incidence estimation of stomach cancer among Koreans

A series of incidence estimation studies of cancers among Koreans through a nationwide survey has been undertaken by authors since 1988. The medical records were studied of inpatients with diagnoses of either ICD-9 151 (malignant neoplasm of the stomach), or 197 (secondary malignant neoplasm of the respiratory and digestive systems), or 211 (benign neoplasm of other parts of the digestive system) in claims sent in by medical care institutions throughout the country to the Korea Medical Insurance Corporation (KMIC) during the period from January 1, 1986 to December 31, 1987. These records were abstracted in order to identify and confirm the new cases of stomach cancer among the beneficiaries of the KMIC, which covers about 10% of whole Korean population. Using these data from the KMIC, the incidence patterns of stomach cancer among Koreans were estimated as of July 1, 1986 to June 30, 1987. The crude incidence rates of stomach cancer among Koreans are estimated to be 36.2 (95% tonfidence interval; 35.3-36.9) and 21.0 (95% CI; 20.3-21.6) per 100,000 in males and females, respectively. The cumulative rates for age spans 0-64 and 0-74 are 3.8% and 7.3% in males, respectively. In females they are 1.8% and 3.0%. The adjusted rates for the world population are 57.9 in males and 25.1 in females, which are similar to those of Shanghai, China '78-'82 but lower than those of Osaka, Japan. The truncated rates for ages 35-64 years, however, are 108.3 in males and 49.1 in females, which may be the highest in the world. Among Koreans in Korea, an increased risk of stomach cancer in this age group is the notable finding. Incidence patterns of stomach cancer by age, sex, and area, which are the first report in Korea, are analyzed and presented.

Incidence rate of hepatitis B: results of a record linkage study among healthy Korean males

A stable, liver disease-free cohort of 369,725 was reconstructed as of 1984 for the study of hepatitis B virus seromarkers and liver diseases. The cohort consisted of male beneficiaries of the Korea Medical Insurance Corporation (KMIC) over 30 years of age and living nationwide. Subjects who were both negatives for HBsAg and anti-HBs (N = 274,037) were selected for incidence of hepatitis B. Data on test results of HBsAg and anti-HBs in 1984 and on hepatitis B occurrence during 1985-1986 were collected from the files of the KMIC. Linkage was done between these two data sets to measure the incidence rate through a longitudinal observation of the male population. Correction against misclassification error and duplicate claims was done by a sample survey and verification procedures. The incidence rate of hepatitis B was 17.13 per 100,000 person-years for acute viral hepatitis B and 15.74 for chronic hepatitis B, respectively. An increasing age-dependent pattern for acute hepatitis B was not so prominent in this population. However, the incidence rate of chronic hepatitis B steadily increased with age. The relative risk, estimated by a log-linear model for rate and constant hazard, was significantly higher in the over-60 age group than in the others. The incidence rate in the lower socioeconomic class was higher than in the others, although statistically not significant.

Cancer and other causes of death among Koreans in Fukuoka, Japan, 1976-1986

Mortalities from cancer and other causes among Koreans living in Fukuoka, Japan, between 1976 and 1986 were examined as compared with those of Japanese in the prefecture. Korean males had a marked excess in all-cause mortality, while the excess among females was less prominent. In both sexes, mortalities from liver cancer, liver cirrhosis, accident and suicide were markedly increased in the Korean population. These findings are in agreement with those observed among Koreans in Osaka. Although 20-30% lower-than-Japanese mortality from stomach cancer has been reported for Koreans in Osaka, those in Fukuoka had a risk of this cancer comparable to that of Japanese. A life-style survey of Koreans in Japan might provide a better understanding of the disease patterns observed in this population.