• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.4045-4050
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• 2012

Objective: The impact of ablative oral cancer surgery was studied, with particular reference to recurrence and nodal metastasis, to assess survival probability and prognostic indicators and to elucidate if ethnicity influences the survival of patients. Methods: Patients who underwent major ablative surgery of the head and neck region with neck dissection were identified and clinical records were assessed. Inclusion criteria were stage I-IV oral and oropharyngeal malignancies necessitating resection with or without radiotherapy from 2004 to 2009. All individuals had a pre-operative assessment prior to the surgery. The post operative assessment period ranged from 1 year to 5 years. Survival distributions were analyzed using Kaplan-Meier curves. Results: 87 patients (males:38%; females:62%) were included in this study, with an age range of 21-85 years. Some 78% underwent neck dissections while 63% had surgery and radiotherapy. Nodal recurrence was detected in 5.7% while 20.5% had primary site recurrence within the study period. Kaplan-Meier survival analysis revealed that the median survival time was 57 months. One year overall survival (OS) rate was 72.7% and three year overall survival rate dropped to 61.5%. On OS analysis, the log-rank test showed a significant difference of survival between Malay and Chinese patients (Bonferroni correction p=0.033). Recurrence-free survival (RFS) analysis revealed that 25% of the patients have reached the event of recurrence at 46 months. One year RFS rate was 85.2% and the three year survival rate was 76.1%. In the RFS analysis, the log-rank test showed a significant difference in the event of recurrence and nodal metastasis (p<0.001). Conclusion: Conservative neck is effective, in conjunction with postoperative radiotherapy, for control of neck metastases. Ethnicity appears to influence the survival of the patients, but a prospective trial is required to validate this.

• Journal of Gastric Cancer
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• v.21 no.4
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• pp.335-351
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• 2021

Purpose: An underlying factor for the failure of several clinical trials of anti-epidermal growth factor receptor (EGFR) therapies is the lack of an effective method to identify patients who overexpress EGFR protein. The quantitative dot blot method (QDB) was used to measure EGFR protein levels objectively, absolutely, and quantitatively. Its feasibility was evaluated for the prognosis of overall survival (OS) of patients with gastric cancer. Materials and Methods: Slices of 2×5 ㎛ from formalin-fixed paraffin-embedded gastric cancer specimens were used to extract total tissue lysates for QDB measurement. Absolutely quantitated EGFR protein levels were used for the Kaplan-Meier OS analysis. Results: EGFR protein levels ranged from 0 to 772.6 pmol/g (n=246) for all gastric cancer patients. A poor correlation was observed between quantitated EGFR levels and immunohistochemistry scores with ρ=0.024 and P=0.717 in Spearman's correlation analysis. EGFR was identified as an independent negative prognostic biomarker for gastric cancer patients only through absolute quantitation, with a hazard ratio of 1.92 (95% confidence interval, 1.05-3.53; P=0.034) in multivariate Cox regression OS analysis. A cutoff of 208 pmol/g was proposed to stratify patients with a 3-year survival probability of 44% for patients with EGFR levels above the cutoff versus 68% for those below the cutoff based on Kaplan-Meier OS analysis (log rank test, P=0.002). Conclusions: A QDB-based assay was developed for gastric cancer specimens to measure EGFR protein levels absolutely, quantitatively, and objectively. This assay should facilitate clinical trials aimed at evaluation of anti-EGFR therapies retrospectively and prospectively for gastric cancer.

• Industry Promotion Research
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• v.7 no.4
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• pp.1-8
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• 2022

There are many one-shot devices that are used once and thrown away. One-shot devices such as firecrackers and ammunition are typical, and they are stored for a while after manufacture and then disposed of after use when necessary. However, unlike general operating systems, these one-shot devices have not been properly evaluated. This study first examines what the government does to secure reliability in the case of ammunition through ammunition stockpile reliability program. Next, in terms of statistical analysis, we show what the reliability analysis methods are for one-shot devices such as ammunition. Specifically, we show that it is possible to know the level of reliability if sampling inspection plan such as KS Q 0001 which is acceptance sampling plan by attributes is used. Next, non-parametric and parametric methods are introduced as ways to determine the storage reliability of ammunition. Among non-parametric methods, Kaplan-Meier method can be used since it can also handle censored data. Among parametric methods, Weibull distribution can be used to determine the storage reliability of ammunition.

• Industry Promotion Research
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• v.7 no.1
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• pp.1-8
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• 2022

We investigated various types of machine learning methods that can be applied to censored data. Exploratory data analysis reveals the distribution of each feature, relationships among features. Next, classification problem has been set up where the dependent variable is death_event while the rest of the features are independent variables. After applying various machine learning methods to the data, it has been found that just like many other reports from the artificial intelligence arena random forest performs better than logistic regression. But recently well performed artificial neural network and gradient boost do not perform as expected due to the lack of data. Finally Kaplan-Meier and Cox proportional hazard model have been employed to explore the relationship of the dependent variable (t_i, δ_i) with the independent variables. Also random forest which is used in machine learning has been applied to the survival analysis with censored data.

• Journal of Chest Surgery
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• v.56 no.3
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• pp.179-185
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• 2023

Background: Assessments of air leaks are usually performed subjectively, precluding the use of air leaks as an evaluation factor. We aimed to identify objective parameters as predictive factors for prolonged air leak (PAL) and air leak cessation (ALC) from air flow data produced by a digital drainage system. Methods: Flow data records of 352 patients who underwent lung lobectomy were reviewed, and flow data at designated intervals (1, 2, and 3 hours postoperatively [POH] and 3 times a day thereafter [06:00, 13:00, 19:00]) were extracted. ALC was defined by flow less than 20 mL/min over 12 hours, and PAL was defined as ALC after 5 days. Cumulative incidence curves were obtained using Kaplan-Meier estimates of time to ALC. Cox regression analysis was performed to determine the effects of variables on the rate of ALC. Results: The incidence of PAL was 18.2% (64/352). Receiver operating characteristic curve analysis showed cut-off values of 180 mL/min for the flow at 3 POH and 73.3 mL/min for the flow on postoperative day 1; the sensitivity and specificity of these values were 88.9% and 82.5%, respectively. The rates of ALC by Kaplan-Meier analysis were 56.8% at 48 POH and 65.6% at 72 POH. Multivariate Cox regression analysis revealed that the flow at 3 POH (≤80 mL/min), operation time (≤220 minutes), and right middle lobectomy independently predicted ALC. Conclusion: Air flow measured by a digital drainage system is a useful predictor of PAL and ALC and may help optimize the hospital course.

• Journal of the Korean Data and Information Science Society
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• v.8 no.1
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• pp.99-109
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• 1997

The estimation procedure of mean residual life function has been placed an important role in the study of survival analysis. In this paper, the product limit estimator on left truncated and right censoring model is proposed with asymptotic properties. Also, the small sample properties are investigated through the Monte Carlo study and the proposed product limit type estimator is compared with ordinary Kaplan-Meier type estimator.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.4
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• pp.341-353
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• 2016

Purpose: The most important factor in longevity studies of dental prostheses is objective and consistent evaluation of the prosthesis. The Korean Academy of Prosthodontics suggested developing a standardized method for longevity studies of dental prostheses. The purpose of this study is to evaluate previously-used criteria and to develop new criteria, in the form of a procedure flowchart and an evaluation sheet. These new criteria may be able to provide a unified standard for future longevity studies of dental prostheses. Materials and methods: A literature review was performed about the evaluation of dental prostheses. Taking into account the strengths and weaknesses of previously used criteria, a novel, intuitive and objective method was developed for assessment of dental prostheses. Then, a pilot survey was performed with the newly developed flowchart and evaluation sheet to determine problems and implement possible improvements. Results: Thirty cases of fixed dental prosthesis (FDP), 25 cases of removable dental prosthesis (RDP), and 13 cases of implant supported prosthesis (ISP) were evaluated. The average life expectancy estimate was 12.82 years for FDP, 5.96 years for RDP, and 4.82 years for ISP with Kaplan-Meier survival analysis. Additionally, possible improvements discovered by the pilot survey were reflected in the flowchart and evaluation sheet. Conclusion: The newly developed KAP criteria, flowchart and evaluation sheet enabled objective and consistent results in trial longevity studies of dental prostheses. It is expected that future studies will not only use the KAP criteria but also further improvement will be made on them.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.2
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• pp.95-104
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• 2018

Purpose: The purpose of this study is to analyze the factors affecting the longevity of failed prosthesis and the success rate of the prosthesis based on the data evaluated with the newly developed Korean Academy of Prosthodontics (KAP) criteria. Materials and methods: Evaluation was performed in the restored prosthesis for patients who visited the prosthodontics department of the 13 dental university hospitals and general hospitals. The status of the prosthesis was classified into four categories: Good, Fair, Bad, Worst. The success was recorded if only the category was classified in 'good'. The mean duration of failed prostheses and the success rate through Kaplan-Meier method were analyzed. Results: A total of 1,804 cases of prosthesis were evaluated: 810 cases of fixed dental prostheses (FDP), 519 cases of Removable Dental Prostheses (RDP), and 475 cases of implant prosthesis. The mean duration of failed FDP was $11.41{\pm}0.30years$ and the median was 10 years. The mean duration of failed RDP was $8.18{\pm}0.29years$ and the median was 7 years. The mean duration of failed implant prosthesis was $7.99{\pm}0.30years$ and the median was 7 years. The factors related to the failure were as follows: number of units, abutments, abutments treated with root canal, and plaque index in FDPs; treated and opposing dentition in RDPs; the number of implants, duration of use, and plaque index in implant prostheses. Conclusion: The average duration of failed prosthesis was 11.41 years for FDPs, 8.18 years for RDPs, and 7.99 years for implant prosthesis, according to the evaluation with newly developed KAP criteria.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.9
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• pp.4079-4083
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• 2014

Background: Previous studies have showed that argonaute 2 is a potential factor related to genesis of several cancers, however, there have been no reports concerning gliomas. Methods: Paraffin specimens of 129 brain glioma cases were collected from a hospital affiliated to Binzhou Medical University from January 2008 to July 2013. We examined both argonaute 2 mRNA and protein expression by real-time quantitative PCR (qRT-PCR), Western blot analysis, and immunohistochemistry (IHC). The survival curves of the patients were determined using the Kaplan-Meier method and Cox regression, and the log-rank test was used for statistical evaluations. Results: Both argonaute 2 mRNA and protein were upregulated in high-grade when compared to low-grade tumor tissues. Multivariate analysis revealed that argonaute 2 protein expression was independently associated with the overall survival (HR=4.587, 95% CI: 3.001-6.993; P=0.002), and that argonaute 2 protein expression and WHO grading were independent prognostic factors for progression-free survival (HR=4.792, 95% CI: 3.993-5.672; P<0.001, and HR=2.109, 95% CI: 1.278-8.229; P=0.039, respectively). Kaplan-Meier analysis with the log-rank test indicated that high argonaute 2 protein expression had a significant impact on overall survival (P=0.0169) and progression-free survival (P=0.0324). Conclusions: The present study showed that argonaute 2 expression is up-regulated in gliomas. Argonaute 2 might also serve as a novel prognostic marker.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.5
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• pp.1839-1843
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• 2015

Background: MicroRNAs are a class of noncoding RNAs which regulate multiple cellular processes during tumor development. The purpose of this report is to investigate the clinicopathological and prognostic significance of miR-218 in human gliomas. Materials and Methods: Quantitative RT-PCR (qRT-PCR) was conducted to detect the expression of miR-218 in primary normal human astrocytes, three glioma cell lines and 98 paired glioma and adjacent normal brain tissues.Associations of miR-218 with clinicopathological variables of glioma patients were statistically analyzed. Finally, a survival analysis was performed using the Kaplan-Meier method and Cox's proportional hazards model. Results: The expression level of miR-218 in primary normal human astrocytes was significantly higher than that in glioma cell lines (p<0.01). Also, the expression level of miR-218 in glioma tissues was significantly downregulated in comparison with that in the adjacent normal brain tissues (p<0.001). Statistical analyses demonstrated that low miR-218 expression was closely associated with advanced WHO grade (p=0.002) and low Karnofsky performance score (p=0.010) of glioma patients. Kaplan-Meier analysis with the log-rank test showed that patients with low-miR-218 expression had poorer disease-free survival and overall survival (p=0.0045 and 0.0124, respectively). Multivariate analysis revealed that miR-218 expression was independently associated with the disease-free survival (p=0.009) and overall survival (p=0.004) of glioma patients. Conclusions: Our results indicate that miR-218 is downregulated in gliomas and that its status might be a potential valuable biomarker for glioma patients.