OBJECTIVES: The objective of this study was to calculate sample size and power in an ongoing cohort, Korea radiation effect and epidemiology cohort (KREEC). METHOD: Sample size calculation was performed using PASS 2002 based on Cox regression and Poisson regression models. Person-year was calculated by using data from '1993-1997 Total cancer incidence by sex and age, Seoul' and Korean statistical informative service. RESULTS: With the assumption of relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, sample size calculation was 405 events based on a Cox regression model. When the relative risk was assumed to be 1.5 then number of events was 170. Based on a Poisson regression model, relative risk=1.3, exposure:non-exposure=1:2 and power=0.8 rendered 385 events. Relative risk of 1.5 resulted in a total of 157 events. We calculated person-years (PY) with event numbers and cancer incidence rate in the non-exposure group. Based on a Cox regression model, with relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, 136 245PY was needed to secure the power. In a Poisson regression model, with relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, person-year needed was 129517PY. A total of 1939 cases were identified in KREEC until December 2007. CONCLUSIONS: A retrospective power calculation in an ongoing study might be biased by the data. Prospective power calculation should be carried out based on various assumptions prior to the study.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Child, Preschool ; Cohort Studies ; Dose-Response Relationship, Radiation ; Female ; Humans ; Incidence ; Infant ; Infant, Newborn ; Male ; Middle Aged ; Neoplasms, Radiation-Induced/*epidemiology ; Republic of Korea/epidemiology ; Risk ; Young Adult

This article was published with an error.

PURPOSE: This study was carried out to predict the mortality rate for gastric cancer up to 2020 in Korea with forecasting model. METHODS: The trends of the age-adjusted mortality rate was calculated from 1983 to 2003 using the mortality data of the past 20 years in Korea, and projected up to the year of 2020 with log-linear models for each gender. The number of deaths from gastric cancer was calculated from the predicted mortality rate. RESULTS: Age-adjusted mortality rates for gastric cancer per 100,000 persons were 32.13 in 1983, 23.95 in 1990, and 15.99 in 2003 for women, and 70.37, 58.74, 41.04 for men, respectively. The expected age-adjusted mortality rates for gastric cancer were 16.50 in 2005, 14.27 in 2010, and 10.66 in 2020 for women, and 39.14, 33.83, 25.28 for men, respectively. In contrast to this decreasing trend, it is predicted that mortality rates for those aged 75 or over would increase steadily. The predicted number of deaths from gastric cancer was 6,519 for women and 13,743 for men in 2020. CONCLUSIONS: This study suggests that gastric cancer mortality rate would decrease continuously except for some aged groups. The declining trends in gastric cancer mortality are regarded as a result of lifestyle changes, improvements in screening methods and treatments. Strategies for aged groups should be developed in order to control increasing mortality rates.
Female ; Forecasting ; Humans ; Korea* ; Life Style ; Linear Models ; Male ; Mass Screening ; Mortality* ; Stomach Neoplasms*

PURPOSE: Cancer has been the leading cause of deaths since 1980s in Korea. Among them, colorectal cancer and breast cancer shows steadily increasing pattern, being the fourth and the fifth common site of cancer death in Korea, respectively. This analysis aimed to evaluate potential contribution of birth cohort effects to the recent increases in mortality of colorectal cancer and breast cancer since 1983 in Korea. METHODS: Mortality statistics on deaths of both cancers for the past 20 years of 1983~2002 were obtained from the National Statistical Office. The age-standardized mortality rates were calculated based on the census population of 1992 as a standard. RESULTS: Age-standardized mortality rate for colorectal cancer increased 4.7-fold in men and 3.6-fold in women, whereas 2.1-fold increase in breast cancer mortality during 1983~2002. Age-specific mortality rates for colorectal cancer were steadily increasing by age before 1991 in both genders. However, the mortality rates showed an exponentially increasing pattern for the age group of 70 and over during 1993~2001, which was more prominent in female. The birth cohort curves showed that there were 2- to 3-fold increases in the mortality rates of people who were born in 1931 for colorectal cancer compared to those of people who were born in 1921. Differences in mortality for breast cancer by birth cohort were 1.7-fold among age group of 45~49 and 50~54 between 1936 and 1946. CONCLUSIONS: This analysis suggests that recent increases in mortality of colorectal cancer and breast cancer could potentially be due to birth cohort effects, i.e. rapid changes in life-style in younger generation. The quantitative approach using age-period-cohort model should be pursued.
Breast Neoplasms* ; Breast* ; Cause of Death ; Censuses ; Cohort Effect* ; Cohort Studies* ; Colorectal Neoplasms* ; Female ; Humans ; Korea* ; Male ; Mortality* ; Parturition*

Objective: The ossification of the ligamentum flavum (OLF) is one of the major causes of thoracic myelopathy. Surgical decompression with or without instrumented fusion is the mainstay of treatment. However, few studies have reported on the added effect of instrumented fusion. The objective of this study was to compare clinical and radiological outcomes between surgical decompression without instrumented fusion (D-group) and that with instrumented fusion (F-group). Methods: A retrospective review was performed on 28 patients (D-group, n=17; F-group, n=11) with thoracic myelopathy due to OLF. The clinical parameters compared included scores of the Japanese Orthopedic Association (JOA), the Visual analogue scale of the back and leg (VAS-B and VAS-L), and the Korean version of the Oswestry disability index (K-ODI). Radiological parameters included the sagittal vertical axis (SVA), the pelvic tilt (PT), the sacral slope (SS), the thoracic kyphosis angle (TKA), the segmental kyphosis angle (SKA) at the operated level, and the lumbar lordosis angle (LLA; a negative value implying lordosis). These parameters were measured preoperatively, 1 year postoperatively, and 2 years postoperatively, and were compared with a linear mixed model. Results: After surgery, all clinical parameters were significantly improved in both groups, while VAS-L was more improved in the Fgroup than in the D-group (-3.4±2.5 vs. -1.3±2.2, p=0.008). Radiological outcomes were significantly different in terms of changes in TKA, SKA, and LLA. Changes in TKA, SKA, and LLA were 2.3°±4.7°, -0.1°±1.4°, and -1.3°±5.6° in the F-group, which were significantly lower than 6.8°±6.1°, 3.0°±2.8°, and 2.2°±5.3° in the D-group, respectively (p=0.013, p<0.0001, and p=0.037). Symptomatic recurrence of OLF occurred in one patient of the D-group at postoperative 24 months. Conclusion Clinical improvement was achieved after decompression surgery for OLF regardless of whether instrumented fusion was added. However, adding instrumented fusion resulted in better outcomes in terms of lessening the progression of local and regional kyphosis and improving leg pain. Decompression with instrumented fusion may be a better surgical option for thoracic OLF.

Objective: To determine whether Sonazoid-enhanced ultrasound (SZUS) was noninferior to SonoVue-enhanced ultrasound (SVUS) in diagnosing hepatocellular carcinoma (HCC) using the same diagnostic criteria. Materials and Methods: This prospective, single-center, noninferiority study (NCT04847726) enrolled 105 at-risk participants (71 male; mean age ± standard deviation, 63 ± 11 years; range, 26–86 years) with treatment-naïve solid hepatic nodules (≥ 1 cm). All participants underwent same-day SZUS (experimental method) and SVUS (control method) for one representative nodule per participant. Images were interpreted by three readers (the operator and two independent readers). All malignancies were diagnosed histopathologically, while the benignity of other lesions was confirmed by follow-up stability or pathology. The primary endpoint was per-lesion diagnostic accuracy for HCC pooled across three readers using the conventional contrast-enhanced ultrasound diagnostic criteria, including arterial phase hyperenhancement followed by mild (assessed within 2 minutes after contrast injection) and late (≥ 60 seconds with a delay of 5 minutes) washout. The noninferiority delta was -10%p. Furthermore, different time delays were compared as washout criteria in SZUS, including delays of 2, 5, and > 10 minutes. Results: A total of 105 lesions (HCCs [n = 61], non-HCC malignancies [n = 19], and benign [n = 25]) were evaluated. Using the 5-minutes washout criterion, per-lesion accuracy of SZUS pooled across the three readers (72.4%; 95% confidence interval [CI], 64.1%–79.3%) was noninferior to that of SVUS (71.4%; 95% CI, 63.1%–78.6%), meeting the statistical criterion for non-inferiority (difference of 0.95%p; 95% CI, -3.8%p–5.7%p). The arterial phase hyperenhancement combined with the 5-minutes washout criterion showed the same sensitivity as that of the > 10-minutes criterion (59.0% vs. 59.0%, p = 0.989), and the specificities were not significantly different (90.9% vs. 86.4%, p = 0.072). Conclusion SZUS was noninferior to SVUS for diagnosing HCC in at-risk patients using the same diagnostic criteria. No significant improvement in HCC diagnosis was observed by extending the washout time delay from 5 to 10 minutes.

PURPOSE: Despite the low mortality rate of breast cancer among women in Korea, the breast cancer mortality rate has increased. The aim of this study was to examine trends in breast cancer mortality from 1983 to 2012 in Korea, assessing the importance of age, period, and birth cohort as risk factors. MATERIALS AND METHODS: Data on the annual number of deaths due to female breast cancer and on female population statistics from 1983 to 2012 were obtained from Statistics Korea. A log-linear Poisson age-period-cohort model was used to estimate age, period, and cohort effects. RESULTS: The increasing breast cancer mortality can be explained predominantly by a birth cohort effect: the risk of breast cancer death showed a steady increase until the 1968 birth cohort, and decreased thereafter. There was a sharp increase in the magnitude of the age effect up to 60 years old, then a moderate increase in the effect during the sixties, followed by another sharp increase from 70 years old. The period effect on breast cancer mortality seems negligible based on its adjusted relative risk, even though it was statistically significant after adjusting for age and cohort effects. CONCLUSION: In this study, the mortality pattern of breast cancer in Korea can be explained predominantly by a birth cohort effect. Hence, the overall mortality rate of breast cancer may increase for a while, and show a gradual decrease in the future, which will start from the younger age group.
Breast Neoplasms* ; Breast* ; Cohort Effect ; Cohort Studies ; Female* ; Humans ; Korea* ; Linear Models ; Mortality* ; Parturition ; Population Characteristics ; Risk Factors

OBJECTIVE: Rheumatoid arthritis (RA) patients suffer from an increased risk of herpes zoster (HZ) partially due to immunosuppressant medications. This study investigated HZ in RA patients treated with biologic disease-modifying antirheumatic drugs (bDMARDs), as compared with conventional DMARDs (cDMARDs). METHODS: This retrospective case series study assembled record information of 277 RA patients who received bDMARDs after failure of at least one cDMARDs at Seoul National University Hospital between August 2003 and February 2015. Following capture of baseline information and identification of HZ episodes, crude HZ incidence rates per 100 patient-years (95% confidence intervals) were calculated. RESULTS: For 718 treatment courses, 277 (38.6%) comprised cDMARDs, 66 (9.2%) infliximab, 175 (24.4%) etanercept, 95 (13.2%) adalimumab, 9 (1.3%) golimumab, 41 (5.7%) rituximab, 31 (4.3%) abatacept, and 24 (3.3%) tocilizumab. There were 37 HZ episodes, 16 during cDMARD treatment courses, and 21 accompanying bDMARDs, two with infliximab, eight with etanercept, five with adalimumab, and three each with rituximab and abatacept. The crude HZ incidence rate per 100 patient-years was 2.4 (1.4∼3.9) for cDMARDs, 2.2 (0.3∼7.9) for infliximab, 1.8 (0.8∼3.6) for etanercept, 3.7 (1.2∼8.4) for adalimumab, 3.9 (0.8∼11.0) for rituximab, and 8.5 (1.8∼23.1) for abatacept. CONCLUSION: We conclude that bDMARDs do not always increase the risk of HZs in RA patients, although HZ rates vary for different bDMARDs.
Abatacept ; Adalimumab ; Antirheumatic Agents ; Arthritis, Rheumatoid* ; Biological Therapy ; Etanercept ; Herpes Zoster* ; Humans ; Incidence ; Infliximab ; Retrospective Studies ; Rituximab ; Seoul

PURPOSE: In spite of gastric cancer's decreasing incidence and mortality rates, it is still the most common cancer in Korea. In the present study, we examined the temporal trends of gastric cancer mortality during the past 20 years in Korea by using an age-period-cohort model, and we predicted the mortality rates for the next 10 years. MATERIALS AND METHODS: Data on the annual number of deaths due to gastric cancer and data on population statistics from 1984 to 2003 were obtained from the Korean National Statistical Office. A log-linear Poisson ageperiod-cohort model was used to estimate age, period and birth cohort effects. To project two periods (10 years) into the future, the new cohort values were estimated by performing linear regression that was applied to a chosen number of the most recent cohort values. RESULTS: The trends of gastric cancer mortality were predominantly explained by the cohort effect; the risk of gastric cancer death decreased since the 1919 birth cohort for both genders. The predicted, expected age-adjusted mortality rates per 100,000 for males and females are 45.72 and 23.75, respectively, during 2004~2008, and 34.62 and 17.93 respectively, during 2009~2013. During 2004~2008 and 2009~2013, the predicted numbers of deaths due to gastric cancer in males are 36,922 and 27,959, respectively, whereas those in females are 19,698 and 14,869, respectively. CONCLUSIONS: Not only the mortality, but also the incidence of gastric cancer in Korea is expected to further decrease in both men and women if the trends of the past 20 years continue.
Cohort Effect ; Cohort Studies ; Female ; Forecasting ; Humans ; Incidence ; Korea* ; Linear Models ; Male ; Mortality* ; Parturition ; Population Characteristics ; Stomach Neoplasms*

We compared the outcomes of allogeneic hematopoietic stem cell transplantation using reduced intensity and myeloablative conditioning for the treatment of patients with advanced hematological malignancies. A total of 75 adult patients received transplants from human leukocyte antigen-matched donors, coupled with either reduced intensity (n=40; fludarabine/melphalan, 28; fludarabine/cyclophosphamide, 12) or myeloablative conditioning (n=35, busufan/cyclophosphamide). The patients receiving reduced intensity conditioning were elderly, or exhibited contraindications for myeloablative conditioning. Neutrophil and platelet engraftment occurred more rapidly in the reduced intensity group (median, 9 days vs. 18 days in the myeloablative group, p<0.0001; median 12 days vs. 22 days in the myeloablative group, p=0.0001, respectively). Acute graft-versus-host disease (> or =grade II) occurred at comparable frequencies in both groups, while the incidence of hepatic veno-occlusive disease was lower in the reduced intensity group (3% vs. 20% in the myeloablative group, p=0.02). The overall 1-yr survival rates of the reduced intensity and myeloablative group patients were 44% and 15%, respectively (p=0.16). The results of present study indicate that patients with advanced hematological malignancies, even the elderly and those with major organ dysfunctions, might benefit from reduced intensity transplantation.
Vidarabine/administration & dosage/*analogs & derivatives ; Treatment Outcome ; Transplantation, Homologous/methods ; Transplantation Conditioning/*methods ; Myeloablative Agonists/*administration & dosage ; Middle Aged ; Male ; International Cooperation ; Humans ; Hematopoietic Stem Cell Transplantation/*methods ; Hematologic Neoplasms/*therapy ; Female ; Busulfan/*administration & dosage ; Aged ; Adult ; Adolescent