• The Korean Journal of Applied Statistics
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• v.34 no.6
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• pp.957-968
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• 2021

Inverse censoring probability weighting (ICPW) is a popular technique in survival data analysis. In applications of the ICPW technique such as the censored regression, it is crucial to accurately estimate the censoring probability. A simulation study is undertaken in this article to see how censoring probability estimate influences model performance in censored regression using the ICPW scheme. We compare three censoring probability estimators, including Kaplan-Meier (KM) estimator, Cox proportional hazard model estimator, and local KM estimator. For the local KM estimator, we propose to reduce the predictor dimension to avoid the curse of dimensionality and consider two popular dimension reduction tools: principal component analysis and sliced inverse regression. Finally, we found that the Cox proportional hazard model estimator shows the best performance as a censoring probability estimator in both mean and median censored regressions.

• Radiation Oncology Journal
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• v.6 no.2
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• pp.295-300
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• 1988

Chordoma is a malignant tumor arising from the primitive notochord involving the axial skeleton. It usually occurs at sacrococcygeal and besisphenoidal area but only rarely does at other vertebral areas, especially at the thoracic vertebrae. It has a slow growth rate and is locally aggressive with an extremely high rate of local recurrence. Either surgery or radiation alone often fails to cure the disease and the local failure is the main cause of treatment failure and death. Overall 5 year survival rate is less than $10\%$. Useful palliation or occasional cure can be obtained by the combination of surgery and radiotherapy. After incomplete resection, the tumor requires radiation dose of 7,000 cGy or more over 6-7 weeks for local control. Tumor regression is slow in response to irradiation and continuation of the regression for several months after completion of RT is not unusual. We report a case of chordoma of the thoracic vertebra, the site of extreme rarity, which showed good local control after partial resection and radiation therapy. He is well and alive without any evidence of recurrence after 13 months of treatment with near complete tumor regression.

• The Journal of Internal Korean Medicine
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• v.28 no.1
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• pp.193-198
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• 2007

Objective : The aim is to derive further studies evaluating the effectiveness of oriental medical treatment on advanced gastric cancer (AGC) patients. We present a case of a stage IV AGC patient who has survived over 8 years. Methods : We followed up all documents related to the patient. We prescribed to the patient HangAmDan (HAD) three times a day over five years. Abdomen CT was performed to evaluate the therapeutic efficacy. Results : The patient has survived over 8 years. Abdomen CT has shown complete regression. Conclusion : This case may give us the possibility of that oriental medical treatment offers potential benefits for patients with AGC.

• Journal of Korean Traditional Oncology
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• v.10 no.1
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• pp.87-91
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• 2005

Objective: It is the aim of the present paper to derive further studies evaluating the effectiveness of oriental medical treatment on SCLC patients. We present a case of SCLC patient who survives over 8 years. Method: We followed all of treatments and examination. We prescribed to the patient what to take HangAmDan (HAD) three times a day. Chest X-ray was performed to evaluate the therapeutic efficacy. Results and conclusion: The patient survives over 8 years. Chest X-rays were shown partial regression. Conclusion: This case may give us a possibility of that oriental medical treatment offers potential benefits for patients with SCLC.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2477-2481
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• 2013

Aims and Background: The purpose of the research was to study the prognostic value of tumor 18F-FDG PET-based parameters in neoadjuvant chemoradiation for patients with squamous esophageal carcinoma. Methods: Sixty patients received chemoradiation therapy followed by esophagectomy and two 18FDG-PET examinations at pre- and post-radiation therapy. PET-based metabolic-response parameters were calculated based on histopathologic response. Linear regression correlation and Cox proportional hazards models were used to determine prognostic value of all PET-based parameters with reference to overall survival. Results: Sensitivity (88.2%) and specificity (86.5%) of a percentage decrease of SUVmax were better than other PET-based parameters for prediction of histopathologic response. Only percentage decrease of SUVmax and tumor length correlated with overall survival time (linear regression coefficient ${\beta}$: 0.704 and 0.684, P<0.05). The Cox proportional hazards model indicated higher hazard ratio (HR=0.897, P=0.002) with decrease of SUVmax compared with decrease of tumor size (HR=0.813, P=0.009). Conclusion: Decrease of SUVmax and tumor size are significant prognostic factors in chemoradiation of esophageal carcinoma.

• Journal of Gastric Cancer
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• v.15 no.3
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• pp.167-175
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• 2015

Purpose: Although several studies report risk factors for anastomotic leakage after gastrectomy for gastric cancer, they have yielded conflicting results. The present retrospective cohort study was performed to identify risk factors that are consistently associated with anastomotic leakage after gastrectomy for stomach cancer. Materials and Methods: All consecutive patients who underwent gastrectomy at a single gastric surgical unit between May 2003 and December 2012 were identified retrospectively. The associations between anastomotic leakage and 23 variables related to patient history, diagnosis, and surgery were assessed and analyzed with logistic regression. Results: In total, 3,827 patients were included. The rate of anastomotic leakage was 1.88% (72/3,827). Multiple regression analysis showed that male sex (P=0.001), preoperative/intraoperative transfusion (P<0.001), presence of cardiovascular disease (P=0.023), and tumor location (P<0.001) were predictive of anastomotic leakage. Patients with and without leakage did not differ significantly in terms of their 5-year survival: 97.6 vs. 109.5 months (P=0.076). Conclusions: Male sex, cardiovascular disease, perioperative transfusion, and tumor location in the upper third of the stomach were associated with an increased risk of anastomotic leakage. Although several studies have reported that an anastomotic complication has a negative impact on long-term survival, this association was not observed in the present study.

• The korean journal of orthodontics
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• v.46 no.2
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• pp.104-110
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• 2016

Objective: Traditional retainers (both metal and fiber-reinforced composite [FRC]) have limitations, and a retainer made from more flexible ligature wires might be advantageous. We aimed to compare an experimental design with two traditional retainers. Methods: In this prospective preliminary clinical trial, 150 post-treatment patients were enrolled and randomly divided into three groups of 50 patients each to receive mandibular canine-to-canine retainers made of FRC, flexible spiral wire (FSW), and twisted wire (TW). The patients were monitored monthly. The time at which the first signs of breakage/debonding were detected was recorded. The success rates of the retainers were compared using chi-squared, Kaplan-Meier, and Cox proportional-hazard regression analyses (${\alpha}=0.05$). Results: In total, 42 patients in the FRC group, 41 in the FSW group, and 45 in the TW group completed the study. The 2-year failure rates were 35.7% in the FRC group, 26.8% in the FSW group, and 17.8% in the TW group. These rates differed insignificantly (chi-squared p = 0.167). According to the Kaplan-Meier analysis, failure occurred at 19.95 months in the FRC group, 21.37 months in the FSW group, and 22.36 months in the TW group. The differences between the survival rates in the three groups were not significant (Cox regression p = 0.146). Conclusions: Although the failure rate of the experimental retainer was two times lower than that of the FRC retainer, the difference was not statistically significant. The experimental TW retainer was successful, and larger studies are warranted to verify these results.

• Korean Journal of Social Welfare
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• v.39
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• pp.5-40
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• 1999

Little is known about unemployment duration and re-employment pattern. This paper empirically examines unemployment duration and re-employment pattern using data by the 1998 national survey about the unemployed and their needs. A parametric survival model(Weibull model) is adopted to identify variables predicting unemployment duration. It is found that the data including people without unemployment insurance as well as people with unemployment insurance fit the Weibull model including the hazard distribution that the hazard of reemployment is increasing at an decreasing rate. Variables that affect unemployment duration are age, householdership, family income, size of prior employment organization, and cause of unemployment. In re-employment pattern, statistically significant variables are age, type of prior employment industry, prior employment pattern, and membership in unemployment insurance. This paper provides a basic knowledge about realities of unemployed individuals in the economic crisis period of Korea, identifies research areas for further research, and develops policy implications for the unemployed.

• Journal of Chest Surgery
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• v.52 no.5
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• pp.360-367
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• 2019

Background: Primary chest wall sarcoma is a rare disease with limited reports of surgical resection. Methods: This retrospective review included 41 patients with primary chest wall sarcoma who underwent chest wall resection and reconstruction from 2001 to 2015. The clinical, histologic, and surgical variables were collected and analyzed by univariate and multivariate Cox regression analyses for overall survival (OS) and recurrence-free survival (RFS). Results: The OS rates at 5 and 10 years were 73% and 61%, respectively. The RFS rate at 10 years was 57.1%. Multivariate Cox regression analysis revealed old age (hazard ratio [HR], 5.16; 95% confidence interval [CI], 1.71-15.48) as a significant risk factor for death. A surgical resection margin distance of less than 1.5 cm (HR, 15.759; 95% CI, 1.78-139.46) and histologic grade III (HR, 28.36; 95% CI, 2.76-290.87) were independent risk factors for recurrence. Conclusion: Long-term OS and RFS after the surgical resection of primary chest wall sarcoma were clinically acceptable.

• Journal of Gastric Cancer
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• v.20 no.4
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• pp.395-407
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• 2020

Purpose: A phase II study was conducted to evaluate the safety and efficacy of preoperative, intra-arterial perfusion of epirubicin, etoposide, and oxaliplatin combined with oral chemotherapy S-1 (SEEOX) for the treatment of type 4 gastric cancer. Materials and Methods: A single-center, single-arm phase II trial was conducted on 36 patients with histologically proven type 4 gastric cancer without distant peritoneal or organ metastasis. Patients received 3, 21-day courses of SEEOX preoperative chemotherapy. The primary endpoint was overall survival (OS) and the secondary outcomes assessed were chemotherapeutic response, radical resection rate, pathological regression, toxicities, postoperative morbidity, and mortality. Results: All patients were at an advanced stage of cancer (stage III or IV) and completed the entire course of treatment. Based on changes in tumor volume and peritoneal metastasis, the objective response rate was 55.6% (20/36; 95% confidence interval [CI], 38.5%-72.6%) and the disease control rate was 69.4% (25/36; 95% CI, 53.6%-85.3%). The radical resection rate was 75% (27/36; 95% CI, 60.1%-89.9%) and the proportion of R0 resections was 66.7% (21/36; 95% CI, 50.5%-82.8%). The pathological response rate was 33.3%, of which 13.9% showed complete pathological regression. The median survival was 27.1 months (95% CI, 22.24-31.97 months), and the 2-year OS was 48.5% (95% CI, 30.86%-66.1%). Conclusions: Preoperative SEEOX is a safe and effective treatment for type 4 gastric cancer. Based on these preliminary data, a phase III study will be conducted to confirm the superiority of this regimen over standard treatment.