Seung-Young Oh

The Value of Postoperative Serum Carcinoembryonic Antigen and Carbohydrate Antigen 19-9 Levels for the Early Detection of Gastric Cancer Recurrence after Curative Resection

Purpose This study aimed to evaluate the value of serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) levels to detect gastric cancer recurrence. Materials and Methods We retrospectively reviewed 154 patients who developed recurrence within 2 years after curative gastric cancer surgery and analyzed the relationship between postoperative CEA and CA19-9 levels and recurrence. We readjusted the cut-off values to improve the detection of recurrence. Subgroup analysis according to clinicopathologic variables was performed to further investigate the relationship between recurrence and CEA and CA19-9 levels. Results The sensitivity and specificity for elevated CEA levels to detect recurrence were 40.6% and 89.5%, respectively, and those for CA19-9 were 34.2% and 93.6%, respectively. The sensitivity and specificity for elevation of either tumor marker were 54.3% and 84.0%, respectively; those for elevation of both tumor markers were 19.2% and 98.4%, respectively. By readjusting the cut-off values from 5.0 ng/ml to 5.2 ng/ml for CEA and from 37.00 U/ml to 30.0 U/ml for CA19-9, the sensitivity was increased from 34.2% to 40.2% for CA19-9, while there was no increase in sensitivity for CEA. In subgroup analysis, the sensitivity of CEA was higher in patients with elevated preoperative CEA levels than in patients with normal preoperative CEA levels (86.7% versus 33.7%; P<0.001). Furthermore, the sensitivity of CA19-9 was higher in patients with elevated preoperative CA19-9 levels than in patients with normal preoperative CA19-9 levels (82.61% versus 26.83%; P<0.001). Conclusions CEA and/or CA19-9 measurement with the readjusted cut-off values allows for more effective detection of gastric cancer recurrence.

Variable selection in subdistribution hazard frailty models with competing risks data

The proportional subdistribution hazards model (i.e. Fine-Gray model) has been widely used for analyzing univariate competing risks data. Recently, this model has been extended to clustered competing risks data via frailty. To the best of our knowledge, however, there has been no literature on variable selection method for such competing risks frailty models. In this paper, we propose a simple but unified procedure via a penalized h-likelihood (HL) for variable selection of fixed effects in a general class of subdistribution hazard frailty models, in which random effects may be shared or correlated. We consider three penalty functions, least absolute shrinkage and selection operator (LASSO), smoothly clipped absolute deviation (SCAD) and HL, in our variable selection procedure. We show that the proposed method can be easily implemented using a slight modification to existing h-likelihood estimation approaches. Numerical studies demonstrate that the proposed procedure using the HL penalty performs well, providing a higher probability of choosing the true model than LASSO and SCAD methods without losing prediction accuracy. The usefulness of the new method is illustrated using two actual datasets from multi-center clinical trials.

Variable Selection in General Frailty Models using Penalized H-likelihood

Variable selection methods using a penalized likelihood have been widely studied in various statistical models. However, in semiparametric frailty models, these methods have been relatively less studied because the marginal likelihood function involves analytically intractable integrals, particularly when modeling multicomponent or correlated frailties. In this article, we propose a simple but unified procedure via a penalized h-likelihood (HL) for variable selection of fixed effects in a general class of semiparametric frailty models, in which random effects may be shared, nested, or correlated. We consider three penalty functions (least absolute shrinkage and selection operator [LASSO], smoothly clipped absolute deviation [SCAD], and HL) in our variable selection procedure. We show that the proposed method can be easily implemented via a slight modification to existing HL estimation approaches. Simulation studies also show that the procedure using the SCAD or HL penalty performs well. The usefulness of the new method is illustrated using three practical datasets too. Supplementary materials for the article are available online.

Lymph Node Metastasis in Mucosal Gastric Cancer: Reappraisal of Expanded Indication of Endoscopic Submucosal Dissection.

Objective: To evaluate risk factors for lymph node (LN) metastasis in mucosal gastric cancer, particularly the effect of cellular differentiation, and implications for the indication of endoscopic submucosal dissection (ESD). Summary Background Data: The indication of ESD has been expanded to undifferentiated-type (UD-type) gastric cancer despite risk of LN metastasis. Methods: Patients who underwent radical gastrectomy for pT1a stage primary gastric adenocarcinoma between 2008 and 2012 were retrospectively analyzed. We evaluated risk factors of LN metastasis using univariate and multivariate analyses. Pathologic slides of primary tumor and metastatic LNs from LN positive patients were reviewed. Results: A total of 1003 mucosal gastric cancer patients were enrolled, and mean number of retrieved LNs was 35.5. Eighteen (1.8%) among them had LN metastasis: 2 of the 502 differentiated-type (D-type) patients and 16 of the 501 UD-type patients (0.4% vs 3.2%, P < 0.001). Type of cellular differentiation was a significant risk factor for LN metastasis in univariate and multivariate analyses. Of 216 UD-type patients satisfying the expanded indication of ESD, 5 patients (2.3%) showed LN metastasis. Despite more aggressive clinical features such as larger size of tumor and more LN metastasis, the UD-type cancer showed a less invasion into the muscularis mucosae layer than the D-type cancer. Conclusions: Because UD-type cancer is a risk factor for LN metastasis in mucosal gastric cancer, ESD cannot be concluded to be a better option than surgery in all UD-type cancer patients. Redefinition of the expanded indication of ESD is required.

Spatial and Temporal Distribution of Plasmodium vivax Malaria in Korea Estimated with a Hierarchical Generalized Linear Model

Objectives The spatial and temporal correlations were estimated to determine Plasmodium vivax malarial transmission pattern in Korea from 2001–2011 with the hierarchical generalized linear model. Methods Malaria cases reported to the Korea Centers for Disease Control and Prevention from 2001 to 2011 were analyzed with descriptive statistics and the incidence was estimated according to age, sex, and year by the hierarchical generalized linear model. Spatial and temporal correlation was estimated and the best model was selected from nine models. Results were presented as diseases map according to age and sex. Results The incidence according to age was highest in the 20–25-year-old group (244.52 infections/100,000). Mean ages of infected males and females were 31.0 years and 45.3 years with incidences 7.8 infections/100,000 and 7.1 infections/100,000 after estimation. The mean month for infection was mid-July with incidence 10.4 infections/100,000. The best-fit model showed that there was a spatial and temporal correlation in the malarial transmission. Incidence was very low or negligible in areas distant from the demilitarized zone between Republic of Korea and Democratic People’s Republic of Korea (North Korea) if the 20–29-year-old male group was omitted in the diseases map. Conclusion Malarial transmission in a region in Korea was influenced by the incidence in adjacent regions in recent years. Since malaria in Korea mainly originates from mosquitoes from North Korea, there will be continuous decrease if there is no further outbreak in North Korea.

The use of random-effect models for high-dimensional variable selection problems

We study the use of random-effect models for variable selection in high-dimensional generalized linear models where the number of covariates exceeds the sample size. Certain distributional assumptions on the random effects produce a penalty that is non-convex and unbounded at the origin. We introduce a unified algorithm that can be applied to various statistical models including generalized linear models. Simulation studies and data analysis are provided.

Laparoscopic management of hypertrophic hypersecretory gastropathy with protein loss: a case report.

Hypertrophic hypersecretory gastropathy with protein loss (HHGP) is a rare form of acquired gastropathy characterized by giant gastric rugal folds and hypoalbuminemia. It is often misdiagnosed as Ménétriers disease. We report the case of a 45‐year‐old man with HHGP who presented with nausea and anorexia. The patient had no underlying disease and was not on medication. Esophagogastroduodenoscopy and CT showed a thickening of the gastric folds in the stomach. As cancer cells were not detected on endoscopic biopsies, the patient was diagnosed with Ménétriers disease. He was managed with a high‐protein diet and annual follow‐up by esophagogastroduodenoscopy. Five years after the diagnosis, the patient underwent laparoscopy‐assisted total gastrectomy for refractory abdominal pain, diarrhea, and protein loss. A pathological diagnosis of HHGP was made and he was discharged without any surgical complications. The patient was relieved of anorexia, abdominal pain, and diarrhea. Laparoscopy‐assisted total gastrectomy could be regarded as a treatment option for HHGP.

Risk Factors of Postoperative Delirium in the Intensive Care Unit After Liver Transplantation

AbstractBackgroundPostoperative delirium after liver transplantation is relatively common, especially due to preexisting conditions such as hepatic encephalopathy. Most studies of delirium after liver transplantation were based on ICU practices using deep hypnosedation. Therefore, risk factors and consequences of postoperative delirium after liver transplantation were evaluated in the light sedation era. MethodsA total of 253 liver transplantation patients were evaluated for postoperative delirium. Clinical outcomes including mortality were compared between patients who suffered delirium and those who did not. Risk factors for postoperative delirium were analyzed with subgroup analysis depending on MELD scores and type of liver transplantation.ResultsPost-liver transplant delirium developed in 17% of the patients, 88% of which occurred within the first postoperative day. Alcoholic liver cirrhosis, class C Child–Pugh score, higher MELD scores, higher proportion of deceased donor liver transplantation, and reintubation were more frequent in patients who developed delirium, but there was no difference in mortality. Higher preoperative MELD group (15–24 vs. <15; OR 4.10, 95% Cl [1.67–10.09], P = 0.002, ≥25 vs. <15; OR 5.59, 95% CI [2.06–15.19], P < 0.01), higher APACHE II scores (OR 5.59, 95% CI [2.06–15.19], P < 0.01), and reintubation (OR 6.46, 95% CI [2.10–19.88], P < 0.01) were identified as significant risk factors for postoperative delirium.ConclusionPostoperative delirium after liver transplantation was associated with worse clinical outcomes. MELD scores greater than 15 were predictive of postoperative delirium in both living and deceased donor liver transplantation.

Open Total Gastrectomy and Splenectomy

Open total gastrectomy remains the standard approach to complete surgica; resection of the stomach. Although laparoscopic techniques and minimally invasive surgery may have advantages in patients requiring distal or subtotal resection, a total gastrectomy requires an esophagojejunal anastomosis. There is debate over the best method to perform this anastomosis and no technique appears to be superior. In this chapter, we describe our approach to open total gastrectomy, highlighting the importance of lymph node dissection and a reliable esophagojejunal anastomotic technique.