• Communications for Statistical Applications and Methods
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• 제25권2호
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• pp.159-172
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• 2018

In many epidemiological studies, missing values in the outcome arise due to censoring. Such censoring is what makes survival analysis special and differentiated from other analytical methods. There are many methods that deal with censored data in survival analysis. However, few studies have dealt with missing covariates in survival data. Furthermore, studies dealing with missing covariates are rare when data are clustered. In this paper, we conducted a simulation study to compare results of several missing data methods when data had clustered multi-structured type with missing covariates. In this study, we modeled unknown baseline hazard and frailty with Bayesian B-Spline to obtain more smooth and accurate estimates. We also used prior information to achieve more accurate results. We assumed the missing mechanism as MAR. We compared the performance of five different missing data techniques and compared these results through simulation studies. We also presented results from a Multi-Center study of Korean IBD patients with Crohn's disease(Lee et al., Journal of the Korean Society of Coloproctology, 28, 188-194, 2012).

• Asian Pacific Journal of Cancer Prevention
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• 제13권5호
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• pp.2003-2007
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• 2012

Purpose: E-cadherin is a transmemberane protein which is responsible for adhesion of endothelial cells. The aim of our study was to assess existing evidence of associations between reduced expression of E-cadherin and prognosis of ovarian cancer with a discussion of potential approaches to exploiting any prognostic value for improved clinical management. Methods: We conducted a meta-analysis of 9 studies (n=915 patients) focusing on the correlation of reduced expression of E-cadherin with overall survival. Data were synthesized with random or fixed effect hazard ratios. Results: The studies were categorized by author/year, number of patients, FIGO stage, histology, cutoff value for E-cadherin positivity, and methods of hazard rations (HR) estimation, HR and its 95% confidence interval (CI). Combined hazard ratios suggested that reduced expression of E-cadherin positivity was associated with poor overall survival (OS), HR= 2.10, 95% CI:1.13-3.06. Conclusion: The overall survival of the E-cadherin negative group with ovarian cancer was significant poorer than the E-cadherin positive group. Upregulation of E-cadherin is an attractive therapeutic approach that could exert significant effects on clinical outcome of ovarian cancer.

• 대한치과의사협회지
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• 제57권10호
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• pp.569-578
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• 2019

The purpose of this retrospective study was to compare outcome of preformed stainless steel crown restorations according to depth of caries in primary molars. The study subjects consisted primary molars having dentin caries extending at least one-fourth of dentin without signs and symptoms of irreversible pulpitis. A total 295 primary molars received preformed stainless steel crown restorations without any base materials were included in this study. Survival rates were compared using a Kaplan-Meier analysis test. There was no significant difference between depth of caries and survival period in primary molars. And also there was no significant difference with or without pulp therapy. The results of this study suggest that neither the amount of caries nor pulp therapy affect the survival period of primary molars significantly. Proper restoration is more important to achieve sealing for stopping caries progression.

• The Journal of Advanced Prosthodontics
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• 제10권3호
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• pp.191-196
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• 2018

PURPOSE. The goal of this study was to evaluate the clinical outcome of single short implants, less than 8 mm in length, placed in the posterior area. MATERIALS AND METHODS. A total of 128 patients (75 male and 53 female, mean age: $52.6{\pm}11.2years$) with 154 implants participated. Implant marginal bone loss, and survival and success rates were measured. RESULTS. The mean follow-up period was $51.35{\pm}24.97months$. A total of 128 implants, 8 mm in length, were placed in patients who had mean marginal bone loss of 0.75 mm. These implants had a survival rate of 95.3%. Twenty-six implants, 7 mm in length, were placed in areas with a mean marginal bone loss of 0.78 mm and had a survival rate of 96.2%. Both marginal bone loss and survival rate were not statistically different among the groups. In the maxilla, 34 implants showed a mean marginal bone loss of 0.77 mm and a survival rate of 97.1%. In the mandible, 120 implants showed a mean marginal bone loss of 0.75 mm and a survival rate of 95.0%. The average marginal bone loss around all implants was $0.76{\pm}0.27mm$ at the last follow-up review after functional loading. The survival rate was 95.6% and success rate was 93.5%. CONCLUSION. In our study, single short implants less than 8 mm in length in the posterior areas had favorable clinical outcomes.

• Journal of Gastric Cancer
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• 제1권1호
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• pp.50-54
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• 2001

Purpose: The aim of this study was to analyze the outcomes of patients with gastrointestinal stromal tumors(GISTs) of the stomach who were treated in our hospital. Materials and Methods: We retrospectively studied 31 patients who were treated for primary gastrointestinal stromal tumors of the stomach from 1990 to 1999 at Korea University Guro Hospital. Clinical characteristics, including age, sex and tumor size were analyzed. In addition, the relation between the 5-year survival rate and tumor size, operative procedure, and malignancy were analyzed to identify the factors that predict survival. Results: The malignant GISTs were 11 cases, borderline GISTs were 2 cases, and benign GISTs were 18 cases. The overall 5-year cumulative survival rate of the patients was $84.6\%$, and the 5-year survival rates according to malignancy were $100\%$ for benign and borderline GISTs and $78.1\%$ for malignant GISTs, p=0.1119. The 5-year survival rates according to tumor size were $100\%$ for tumor sizes smaller than 5 cm and $78.4\%$ for tumor sizes larger than 5 cm, p=0.0453. The 5-year survival rate according to lymph node dissection during operative procedure of malignant GISTs was not significant statistically. Conclusions: GISTs of the stomach are infrequently encountered tumors. Tumor size was the most important factor for predicting survival in a clinical situation, and performing a complete resection of the tumor, especially tumors larger than 5 cm, will improve the outcome of treatment.

• Asian Pacific Journal of Cancer Prevention
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• 제15권4호
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• pp.1585-1588
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• 2014

Background: Data regarding childhood and adolescent non Hodgkin lymphomas in Iran are limited. The aim of this study was to assess the epidemiological and histomorphological features and survival of affected patients in our center. Materials and Methods: The clinicopathologic features and outcome of 44 children and adolescents with non Hodgkin lymphoma diagnosed during 2004-2012, were investigated retrospectively. The influence of potential prognostic parameters in overall survival was investigated by log-rank test and Cox regression analysis. Results: The mean age at presentation was $13.8{\pm}6.16$ years with a male predilection (M: F=3:1). Malignant lymphoma, not otherwise specified, diffuse large cell lymphoma and Burkitt lymphoma were the three most common histological types observed. The tumors were 36.4% intermediate grade, 27.3% high grade and 34.1% belonged to the malignant lymphoma not otherwise specified group. Immunohistochemistry findings were available in 39 cases. Out of these cases 33 (84.6%) had B cell lineage, 4 (10.25%) T cell lineage and 2 (5.12%) of the cases belonged to miscellaneous group. 3 year and 5 year survivals were 48% and 30% respectively and median survival was 36 months (95%CI=21.7-50.3 months). Overall survival in patients with high grade tumors was 19.5 months, in the intermediate group,79 months, and for malignant lymphomas not otherwise specified it was 33.6 months (p value=0.000). Conclusions: The survival rate for children and adolescents with non Hodgkin lymphomas at our center during 2004-2012 was at a low level.

• Asian Pacific Journal of Cancer Prevention
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• 제13권3호
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• pp.1053-1057
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• 2012

Objective: Identifying cancer-related genes or proteins is critical in preventing and controlling colorectal cancer (CRC). This study was to investigate the clinicopathological and prognostic value of activating transcription factor 1 (ATF1) in CRC. Methods: Protein expression of ATF1 was detected using immunohistochemistry in 66 CRC tissues. Clinicopathological association of ATF1 in CRC was analyzed with chi-square test or Fisher's exact test. The prognostic value of ATF1 in CRC is estimated using the Kaplan-Meier analysis and Cox regression models. Results: The ATF1 protein expression was significantly lower in tumor tissues than corresponding normal tissues (51.5% and 71.1%, respectively, P = 0.038). No correlation was found between ATF1 expression and the investigated clinicopathological parameters, including gender, age, depth of invasion, lymph node status, metastasis, pathological stage, vascular tumoral emboli, peritumoral deposits, chemotherapy and original tumor site (all with P > 0.05). Patients with higher ATF1 expression levels have a significantly higher survival rate than that with lower expression (P = 0.026 for overall survival, P = 0.008 for progress free survival). Multivariate Cox regression model revealed that ATF1 expression and depth of invasion were the predictors of the overall survival (P = 0.008 and P = 0.028) and progress free survival (P = 0.002 and P = 0.005) in CRC. Conclusions: Higher ATF1 expression is a predictor of a favorable outcome for the overall survival and progress free survival in CRC.

• Asian Pacific Journal of Cancer Prevention
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• 제14권8호
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• pp.4567-4570
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• 2013

Background: Nasopharyngeal carcinoma (NPC) is the commonest radiocurable cancer in Malaysia. This study aimed to determine the treatment outcomes and late effects of radiotherapy for NPC patients treated in University Malaya Medical Centre (UMMC). Materials and Methods: All newly diagnosed patients with NPC referred for treatment to the Oncology unit at UMMC from 2004-2008 were retrospectively analyzed. Treatment outcomes were 5 years overall survival (OS), disease free survival (DFS), cause-specific survival (CSS), locoregional control (LRC) and radiotherapy-related late effects. The Kaplan-Meier method was used for survival analysis and differences in survival according to AJCC stage was compared using the log-rank test. Results: A total of 176 patients with newly diagnosed NPC were treated in UMMC during this period. Late presentation was common, with 33.5% presenting with T3-4 disease, 84.7% with N1-3 disease and 75.6% with AJCC stage 3-4 disease. Radical RT was given to 162 patients with 22.7% having RT alone and 69.3% having CCRT. The stipulated OTT was 7 weeks and 72.2% managed to complete their RT within this time period. Neoadjuvant chemotherapy was given to 14.8% while adjuvant chemotherapy was administered to 16.5%. The 5 years OS was 51.6% with a median follow up of 58 months. The 5 years OS according to stage were 81.8% for stage I, 77.9% for stage II, 47.4% for stage III and 25.9% for stage IV. The 5 years overall CSS, DFS and LRC were 54.4%, 48.4% and 70.6%, respectively. RT related late effects were documented in 80.2%. The commonest was xerostomia (66.7%). Other documented late effects were hearing deficit (17.3%), visual deficit (3.1%), neck stiffness (3.1%), dysphagia (3.4%), cranial nerve palsy (2.5%), pneumonitis (0.6%) and hypothyroidism (1.2%). Conclusions: The 5 years OS and LRC in this study are low compared to the latest studies especially those utilizing IMRT. Implementation of IMRT for NPC treatment should be strongly encouraged.

• Asian Pacific Journal of Cancer Prevention
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• 제17권4호
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• pp.1759-1767
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• 2016

Background: Uterine sarcoma is a group of rare gynecologic tumors with various natures, and different lines of treatment. Most have a poor treatment outcome. This study targeted clinical characteristics, treatment, overall survival (OS), progression-free survival (PFS), and prognostic factors in uterine sarcoma patients in one tertiary center for cancer care. Materials and Methods: Uterine sarcoma patients who were treated at the Department of Obstetrics and Gynecology, Faculty of Medicine Vajira Hospital between January 1994 and December 2014 were identified. Clinico-pathological data were analyzed. Prognostic outcomes were examined by Kaplan-Meier curves and Cox regression analysis. Results: We identified 46 uterine sarcoma patients: 25 carcinosarcoma (CS) (54.3%), 15 leiomyosarcoma (LMS) (32.6%), and 6 undifferentiated uterine sarcoma (UUS) (13.1%) cases. Mean age was $54.0{\pm}11.9years$ (range 25-82 years). Abnormal uterine bleeding was the most common presenting symptom (63.0%). Among 33 patients (71.7%) who had pre-operative tissue collected, diagnosis of malignancy was correct in 29 (87.9%). All patients received primary surgery and retroperitoneal lymph nodes were resected in 34 (73.9%). After surgery, 5 (10.9%) had gross residual tumors. Stage I disease was most commonly found (56.5%). Adjuvant treatment was given to 27 (58.7%), most commonly chemotherapy. After a median follow-up of 16.0 months (range 0.8-187.4 months), recurrence was encountered in 22 patients (47.8%). Median time to recurrence was 5.8 months (range1.0-105.5 months). Distant metastasis was more common than local or locoregional failure. The 2-year PFS was 45.2% (95% confidence interval [CI], 30.6%-59.7%) and the 2-year OS was 48.3% (95% CI, 33.3%-60.7%). Multivariable analyses found residual disease after surgery as a significant factor only for PFS. Conclusions: Uterine sarcoma is a rare tumor entity. Even with multimodalities of treatment, the prognosis is still poor. Successful cytoreductive surgery is a key factor for a good survival outcome.

• Asian Pacific Journal of Cancer Prevention
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• 제13권5호
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• pp.2101-2107
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• 2012

Treatment responses of $N_0$ stage nasopharyngeal carcinoma were firstly analyzed comprehensively to evaluate long term outcomes of patients and identify prognostic factors. A total of 610 patients with $N_0$ NPC, undergoing definitive radiotherapy to their primary lesion and prophylactic radiation to upper neck, were reviewed retrospectively. Concomitant chemotherapy was administrated to 65 out of the 610. Survival rates of the patients were calculated using the Kaplan-Meier method and compared by log-rank test. Prognostic factors were identified by the Cox regression model. The study revealed the 5-year and 10-year overall, disease-free, disease-specific, local failure-free, regional failure-free, locoregional failure-free and distant metastasis-free survival rates to be 78.7% and 66.8%, 68.8% and 55.8%, 79.9% and 70.4%, 81.2% and 72.5%, 95.8% and 91.8%, 78.3% and 68.5%, 88.5% and 85.5%, respectively. There were 192 patients experiencing failure (31.5%) after radiotherapy or chemoradiotherapy. Of these, local recurrence, regional relapse and distant metastases as the first event of failure occurred in 100 (100/610, 16.4%), 15(15/610, 2.5%) and 52 (52/610, 8.5%), respectively. Multivariate analysis showed that T stage was the only independent prognostic factor for patients with $N_0$ NPC (P=0.000). Late T stage (P=0.000), male (P=0.039) and anemia (P=0.007) were independently unfavorable factors predicting disease-free survival. After treatment, satisfactory outcome wasgenerally achieved in patients with $N_0$ NPC. Local recurrence represented the predominant mode of treatment failure, while T stage was the only independent prognostic factor for overall survival. Late T stage, male gender, and anemia independently predicted lower possibility of the disease-free survival.