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Simulation and seasonal prediction of the cold surge characteristics over the Korean Peninsula by the Pusan National University CGCM (PNU CGCM), a participating model in Asia–Pacific Economic Cooperation Climate Center Multi-Model Ensemble Prediction System, are evaluated based on historical seasonal forecasts for 42 years (1980 − 2021). The PNU CGCM skillfully simulates the climatological characteristics of the cold surges of the non-blocking type (nB_CS), and of two blocking types (B_CS), particularly the Ural and Okhotsk blocking types (UR_CS and OK_CS). In both observation and the PNU CGCM simulations, nB_CS is the most frequent type of the cold surges over the Korean Peninsula. Duration and intensity of the nB_CSs are perfectly simulated. However, the number of occurrences and number of days are overestimated. In the model simulations, the number of occurrences and number of days of the UR_CS tend to be overestimated while those of the OK_CS tend to be underestimated. Meanwhile, for each type of cold surges, the difference in probability distributions of the simulated and observed cold surge duration and intensity is not statistically significant. Also, PNU CGCM skillfully simulates spatial–temporal evolution of the wave-train pattern causing the nB_CS, as well as spatial–temporal evolution of both B_CSs, associated with the blocking of the barotropic structure and the passage over the Korean Peninsula of trough of the baroclinic structure. Overall, seasonal predictions of the PNU CGCM are skillful for the wintertime total number of days with the cold surges, and mean intensity of the cold surges. [ABSTRACT FROM AUTHOR]

This study investigated future projections of extreme precipitation (PR) over the Korean Peninsula (KP) under global warming levels of 1.5 °C and 2.0 °C (GWL 1.5 °C and 2.0 °C). The bias-corrected large ensemble of the Regional Climate Model (RCM) in the Coordinated Regional Climate Downscaling Experiment–East Asia Phase 2 was used. Under GWL 1.5 °C, the RCM multi-model ensemble (MME) predicted the extreme PR intensity (RX1day) to increase by 10.14% more than the mean PR of 4.69%. A regional difference was observed in the projection, with a larger increase over the northern KP (NKP) and southern KP (SKP) than central KP. Accordingly, the distribution of extreme PR was expected to shift with the right, and extreme events occurring once every 20 years over the SKP and NKP were expected to change to a reoccurrence of 12.56 years and 10.04 years, respectively. The mechanism of extreme PR was examined for cases from June to September. The expected increase in extreme PR per warming over the SKP and NKP was 5.64% °C−1 and 8.37% °C−1, respectively, which was close to the Clausius-Clapeyron scale (7.7% °C−1). This implies that increased moisture capability from the warming will affect the change in extreme PR. Other possible factors were investigated and the RCM MME predicted vertical instability over East Asia to continue, and moisture flux and convergence around the KP to be intensified. Meanwhile, under GWL 2.0 °C, mean PR and extreme PR were projected to increase more than under GWL 1.5 °C. [ABSTRACT FROM AUTHOR]

This study examines the factors affecting the 2m‐temperatures (T2m) in South Korea in winter (DJF) from 1979/1980 to 2018/2019. For this purpose, we performed an empirical orthogonal function (EOF) analysis of the geopotential height at 500 hPa in the region 15°–75°N, 70°E–180° centred around the Korean Peninsula. The first EOF mode, which accounted for 31.1% of the total variance of the winter T2m in the region, is related to the KamChatka Blocking Frequency (KCBF). The second mode, which accounted for 18.3%, is associated with East Asian winter monsoon (EAWM). In addition to EOF analysis, the partial correlation (PC) analysis also confirmed that KCBF Index and EAWM Index, which are highly correlated with the winter T2ms in South Korea, are independent of each other. The individual and combined effects of the KCBF and EAWM are examined because they independently affect the winter T2ms in South Korea. According to the composite analysis, in the years when KCBF is higher than normal (H_KCBF), negative and positive Z500 anomalies are located over the south Sea of Japan and the Kamchatka Peninsula, respectively. In other words, the positive geopotential anomaly over the Kamchatka Peninsula lowers the T2ms of South Korea by blocking the flow of cold air moving eastward from the Korean Peninsula. In the years when a strong EAWM occurred (S_EAWM), negative and positive Z500 anomalies are located over the Manchuria region and the northwestern regions of Russia, respectively. Consequently, cold air in the north moves southward, resulting in lower T2ms in South Korea. For the combined effects of KCBF and EAWM on the T2ms, winters of 40 years are categorized into L_KCBF‐W_EAWM, L_KCBF‐S_EAWM, H_KCBF‐W_EAWM and H_KCBF‐S_EAWM years. The analyses show that when KCBF and EAWM are in phase, the T2ms in South Korea are more prominent than when they are out‐of‐phase. [ABSTRACT FROM AUTHOR]

Rice production in the Korean Peninsula (KP) in the near future (2021–2050) is analysed in terms of the climatic yield potential (CYP) index for Japonica‐type rice. Data obtained from the dynamically downscaled daily temperature and sunshine duration for the Historical period (1981–2010) and near future under two Representative Concentration Pathway (RCP4.5 and RCP8.5) scenarios are utilized. To reduce uncertainties that might be induced by using a Coupled General Circulation Model (CGCM)—a Regional Climate Model (RCM) chain in dynamical downscaling, two CGCM—three RCM chains are used to estimate the CYP index. The results show that the mean rice production decreases, mainly due to the increase of the temperature during the grain‐filling period (40 days after the heading date). According to multi model ensemble, the optimum heading date in the near future will be approximately 12 days later and the maximum CYP will be even higher than in the Historical. This implies that the rice production is projected to decrease if the heading date is selected based on the optimum heading date of Historical, but to increase if based on that of near future. The mean rice production during the period of ripening is projected to decrease (to about 95% (RCP4.5) and 93% (RCP8.5) of the Historical) in the western and southern regions of the KP, but to increase (to about 104% (RCP4.5) and 106% (RCP8.5) of the Historical) in the northeastern coastal regions of the KP. However, if the optimum heading date is selected in the near future climate, the peak rice production is projected to increase (to about 105% (RCP4.5) and 104% (RCP8.5) of the Historical) in the western, southern and northeastern coastal regions of the KP, but to decrease (to about 98% (RCP4.5) and 96% (RCP8.5) of the Historical) in the southeastern coastal regions of the KP. [ABSTRACT FROM AUTHOR]

Background: Converting chemotherapy followed by surgery is known to be associated with improved clinical outcomes in colorectal cancer (CRC) patients with hepatic metastasis. This study is to investigate the clinicopathological prognostic factors for disease-free survival (DFS) after curative resection of primary and metastatic lesions. Methods: We retrospectively analyzed the medical records of 76 CRC patients who had initially had unresectable hepatic metastasis, which was considered resectable after systemic chemotherapy, and had undergone curative surgery in the period from January 2006 to December 2011. DFS was compared by assessing clinical data including age, sex, staging, number of hepatic lesion(s), size of the largest hepatic lesion and serum carcinoembryonic antigen (CEA) levels. Results: The median age was 57 years and 47 patients were male. The median DFS was 10.4 months. Multivariate Cox regression analysis revealed that age <50 years (HR 2.70, 95% CI 1.43-5.10, p = 0.002) and CEA elevation after curative surgery (HR 2.20, 95% CI 1.11-4.36, p = 0.023) were associated with a shorter DFS. Conclusions: Given that patients <50 years old or with elevated CEA levels after curative surgery demonstrated a short DFS, additional postoperative systemic treatment or active surveillance, at least, should strongly be considered for this group. © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Purpose: Ethnic diversity of genetic polymorphism can result in individual differences in the efficacy and toxicity of cancer chemotherapy., Methods: We analyzed 20 germline polymorphisms in 10 genes (TS, MTHFR, ERCC1, XPD, XRCC1, ABCC2, AGXT, GSTP1, GSTT1 and GSTM1) from prospectively enrolled 292 Korean patients treated with adjuvant oxaliplatin plus leucovorin plus 5-fluorouracil (FOLFOX) for colon cancer., Results: In contrast to previous studies in Caucasians, neutropenia (grade 3-4, 60.5 %) was frequently observed, whereas only 16.4 % experienced grade 2 or more sensory neuropathy. Neutropenia was more frequent in MTHFR 677TT [adjusted odds ratio (OR) 2.32, 95 % confidence interval (CI) 1.19-4.55] and ERCC1 19007TT (adjusted OR 4.58, 95 % CI 1.20-17.40) genotypes. Patients harboring XRCC1 23885GG experienced less grade 2-4 neuropathy [adjusted OR 0.52, 95 % CI 0.27-0.99]. MTHFR 677TT (p = 0.002) and XRCC1 23885GG (p = 0.146) genotypes were also more prevalent in Koreans compared to Caucasians. TS 'low' genotype (adjusted HR 1.83, 95 % CI 1.003-3.34) was significantly related to shorter disease-free survival. Overall survival was not significantly different according to the polymorphisms., Conclusions: Polymorphisms in MTHFR, XRCC1 and TS are related to toxicities and disease-free survival in patients with colon cancer. The ethnic differences in frequencies of genotypes may explain the ethnic difference in toxicity profile following adjuvant FOLFOX chemotherapy.

Background: Adjuvant Online (AOL) is web-accessible risk-assessment model that predicts the mortality and the benefits of adjuvant therapy (http://www.newadjuvantonline.com). AOL has never been validated for Asian colon cancer patients., Methods: Using the Yonsei Tumor Registry database, patients who were treated within the Yonsei University Health System between 1990 and 2005 for T1-4, N0-2, and M0 colon cancer were included in the calculations for survival. Observed and predicted 5-year overall survival was compared for each patient., Results: The median age of the study population of 1431 patients was 60 years (range, 15-87 years), and the median follow-up duration was 7.9 years (range, 0.06-19.8 years). The predicted 5-year overall survival rate (77.7%) and observed survival (79.5%) was not statistically different (95% Confidential interval, 76.3-81.5) in all patients. Predicted outcomes were within 95% confidential interval of observed survival in both stage II and III disease, including most demographic and pathologic subgroups. Moreover, AOL more accurately predicted OS for patients with stage II than stage III., Conclusions: AOL tended to offer reliable prediction for 5-year overall survival and could be used as a decision making tool for adjuvant treatment in Korean colon cancer patients whose prognosis is similar to other Asian patients.

Objective: In this study, we compared the pharmacokinetic profiles of 5-fluorouracil (5-FU), tegafur, 5-chloro-2,4-dihydroxypyridine (CDHP) and potassium oxonate (Oxo) after administration of S-1 at 35 or 40 mg/m(2) bid for 28 consecutive days, in Cycles 1 and 3, in patients with advanced gastric cancer., Methods: Three patients were enrolled for each dosage. S-1 dosage was assigned based on body surface area (BSA), which is different from the Japanese dosing system. The median daily dose per BSA was 76 mg/m(2), ranging from 70 to 88 mg/m(2)., Results: Plasma levels of 5-FU, tegafur, CDHP and Oxo at 4 h post-dose reached steady-state on day 8. The estimated steady-state level was dependent on S-1 dosage. There were no intercyclic differences of pre-dose and 4 h post-dose levels between Cycles 1 and 3, implying no cumulative effect of S-1 was shown probably due to 2-week drug-resting period. Pharmacokinetic profiles on day 28 were similar to previous Japanese report. C(max) and AUC(0-48 h) values of each S-1 component increased depending on S-1 dosage. Pharmacokinetic parameters were not correlated with tumor response or toxicity., Conclusions: We suggest that these pharmacokinetic profiles of Asian population could provide a basis for schedule optimization and for additional studies on interaction with other antitumor drugs.

Mental adjustment and coping affect the physical outcome and survival as well as quality of life in cancer patients. The Mini-Mental Adjustment to Cancer (Mini-MAC) scale is a new refined, economical and reliable self-rating instrument measuring cognitive and behavioral responses to cancer. The aim of this study was to evaluate the psychometric properties of the Mini-MAC in Korean cancer patients. A total of 208 cancer patients recruited from the Yonsei Cancer Center were assessed with the Mini-MAC and the Hospital Anxiety and Depression Scale (HADS). Principal component analysis with varimax rotation for the Korean version of Mini-MAC (K-Mini-MAC) confirmed four factors. Three had psychometric properties similar to Helpless-Hopeless (HH), Anxious Preoccupation (AP) and Cognitive Avoidance (CA) of the original Mini-MAC. A novel factor, named Positive Attitude, included items of both Fatalism (FA) and Fighting Spirit (FS) from the original version. The five subscales from the original version (AP, HH, FS, FA and CA) and Positive Attitude had acceptable internal reliabilities in our sample (Cronbach's alpha coefficient 0.50-0.86; correlation coefficient of test-retest 0.68-0.88). For the validity, significant interscale correlation was observed in the original five subscales and Positive Attitude. Each subscale including Positive Attitude was also significantly related to Depression and Anxiety of HADS. As a whole, the K-Mini-MAC was a reliable, valid and acceptable tool for Korean cancer patients. These findings can provide information about the cross-cultural validity of Mini-MAC scale's factor structure. Cultural differences were also discussed.