• Proceedings of the KOR-BRONCHOESO Conference
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• 1993.05a
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• pp.95-95
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• 1993

Even though maxillary cancer is usually discovered in advanced stage, its regional lymph node or distant metastases are not common comparing to other head and neck cancer. So the result of treatment depends upon local control of the tumor. Because maxillary sinus is anatomically located adjacent to orbit and skull base, it is difficult to remove the tumor completely with sufficient safety margin like in other malignant tumor. Traditionally, surgery including aggressive resection, radiotherapy or both combined therapy have been widely accepted in many institutes, but their results are not still satisfactory. Sixteen cases of maxillary cancer( all squamous cancer, T2 1 case, T3 6 cases, T4 9 cases, mean age 57.2 years) were treated by intraarterial chemotherapy, raditherapy and surgery and followed up retrospectively. 5 year survival rate by Kaplan-Meier method was 51.95%, and orbit, palate or cheek skin could be preserved in many cases and their functional result was good.

• The Korean Journal of Applied Statistics
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• v.24 no.5
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• pp.871-881
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• 2011

In this paper we propose a logistic regression method to estimate the survival function and the median survival time in interval-censored data. The proposed method is motivated by the data augmentation technique with no sacrifice in augmenting data. In addition, we develop a cross validation criterion to determine the size of data augmentation. We compare the proposed estimator with other existing methods such as the parametric method, the single point imputation method, and the nonparametric maximum likelihood estimator through extensive numerical studies to show that the proposed estimator performs better than others in the sense of the mean squared error. An illustrative example based on a real data set is given.

• Journal of the military operations research society of Korea
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• v.6 no.2
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• pp.129-149
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• 1980

In medical follow-up, equipment lifetesting, various military situations, and other fields, one often desires to calculate survival probability as a function of time, p(t). If the observer is able to record the time of occurrence of the event of interest (called a 'death'), then an empirical, non-parametric estimate may simply by obtained from the fraction of survivors after various elapsed times. The estimation is more complicated when the data are truncated, i.e., when the observer loses track of some individuals before death occurs. The product-limit method of Kaplan and Meier is one way of estimating p(t) when the mechanism causing truncation is independent of the mechanism causing death. This paper proposes jackknife estimators of logistic trans-formation and compares it to the product-limit method. A computer simulation is used to generate the times of death and truncation from a variety of assumed distributions.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.1
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• pp.159-163
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• 2013

Background: This study used Surveillance, Epidemiology and End Results (SEER) pancreatic cancer data to identify predictive models and potential socio-economic disparities in pancreatic cancer outcome. Materials and Methods: For risk modeling, Kaplan Meier method was used for cause specific survival analysis. The Kolmogorov-Smirnov's test was used to compare survival curves. The Cox proportional hazard method was applied for multivariate analysis. The area under the ROC curve was computed for predictors of absolute risk of death, optimized to improve efficiency. Results: This study included 58,747 patients. The mean follow up time (S.D.) was 7.6 (10.6) months. SEER stage and grade were strongly predictive univariates. Sex, race, and three socio-economic factors (county level family income, rural-urban residence status, and county level education attainment) were independent multivariate predictors. Racial and socio-economic factors were associated with about 2% difference in absolute cause specific survival. Conclusions: This study s found significant effects of socio-economic factors on pancreas cancer outcome. These data may generate hypotheses for trials to eliminate these outcome disparities.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.4
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• pp.2567-2570
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• 2013

Background: This study analyzed Surveillance, Epidemiology and End Results (SEER) data to assess if socio-economic factors (SEFs) impact on endometrial cancer survival. Materials and Methods: Endometrial cancer patients treated from 2004-2007 were included in this study. SEER cause specific survival (CSS) data were used as end points. The areas under the receiver operating characteristic (ROC) curve were computed for predictors. Time to event data were analyzed with Kaplan-Meier method. Univariate and multivariate analyses were used to identify independent risk factors. Results: This study included 64,710 patients. The mean follow up time (S.D.) was 28.2 (20.8) months. SEER staging (ROC area of 0.81) was the best pretreatment predictor of CSS. Histology, grade, race/ethnicity and county level family income were also significant pretreatment predictors. African American race and low income neighborhoods decreased the CSS by 20% and 3% respectively at 5 years. Conclusions: This study has found significant endometrial survival disparities due to SEFs. Future studies should focus on eliminating socio-economic barriers to good outcomes.

• Journal of Korean Society for Quality Management
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• v.25 no.3
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• pp.96-107
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• 1997

The recent stream to reliability prediction is that it is totally inclusive in depth to consider even the operating and environmental condition at the level of finished goods as well as component itselves. In this study, firstly we present the reliability prediction methods by entire failure rate model which failure rate at the system level is added to the failure rate model at the component level. Secondly we build up the improved bases of reliability demonstration through a, pp.ication of Kaplan-Meier, Cumulative hazard, Johnson's methods as non-parametric and Maximum Likelihood Estimator under exponential & Weibull distribution as parametric. And also present the methods of curve fitting to piecewise failure rate under Weibull distribution, PRST (Probability Ratio Sequential Test), curve fitting to S-shaped reliability growth curve, computer programs of each methods. Lastly we show the practical for determination of optimal burn-in time as a method of reliability enhancement, and also verify the practical usefulness of the above study through the a, pp.ication of failure and test data during 1 year.

• The Korean Journal of Applied Statistics
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• v.20 no.2
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• pp.313-322
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• 2007

Several robust censored depth regression methods are compared under contamination. Park and Hwang(2003) suggested a way to circumvent the censoring issue by incorporating Kaplan-Meier type weight in halfspace regression depth and Park(2003) used a similar technique to simplicial regression depth. Hubert et al. (2001) suggested a high breakdown point regression depth based on projection called rcent. A new method to implement censoring in rcent is suggested and compared with two precedents under various contamination and censoring schemes.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.154-157
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• 2010

In this paper, the Time-varying Failure Rates(TFR) of power distribution system components are extracted from the recorded failure data of KEPCO(Korea Electric Power Corporation) and the reliability of power distribution system is evaluated using Mean Failure Rate(MFR) and TFR. The TFR is approximated to bathtub curve using the exponential and Weibull distribution function. In addition, Kaplan-Meier estimation is applied to TFR extraction because of incomplete failure data of KEPCO. Also the reliability of the real power distribution system of Korea is evaluated using the MFR and TFR extracted from real failure data, respectively and the results of each case are compared with each other. As a result, it is proved that the reliability evaluation using the TFR is more realistic than MFR. In addition, it is presented that the application method at power distribution system maintenance and repair using the result of TFR.

• Journal of Chest Surgery
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• v.42 no.5
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• pp.610-614
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• 2009

Background: Several trials have reported on whether adjuvant chemotherapy for resected stage IB non-small cell lung cancer is needed. The aim of our study was to investigate prognostic factors for recurrence to help identify patients who should receive adjuvant chemotherapy. Material and Method: We reviewed the cases of 48 stage IB non-small cell lung cancer patients between 1997 and 2006. Disease-free survival and overall survival rates were calculated by the Kaplan-Meier method. Univariate analysis was performed with the log rank test and multivariate analysis was done using Cox's proportional hazard model. Result: The median follow-up time was 48 months. The overall survival rate was 55.9%, and the disease-free survival rate was 48.6%. Of 8 variables, two factors, visceral pleural invasion and Iymphovascular invasion, were prognostic factors of disease-free survival (univariate analysis). Visceral pleural invasion was a significant prognostic factor in multivariate analysis, and overall survival in com-pared one or more variable such as visceral pleural invasion or, and lymphovascular invasion with the other variables. Conclusion: Visceral pleural invasion was identified as a poor prognostic factor and it may help select which patients will benefit from adjuvant chemotherapy in addition to more comprehensive follow-up.

• The Journal of the Korean bone and joint tumor society
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• v.18 no.1
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• pp.7-13
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• 2012

Purpose: The purpose of this study is to compare general survival rate and survival rate according to expectable prognostic factors by analyzing the result of treating a patient of squamous cell carcinoma. Materials and Methods: From Mar. 1999 to Feb. 2011, 151 patients were pathologically confirmed as squamous cell carcinoma of limbs and body in our hospital, and among those patients, 51 patients underwent the surgical treatment. This study included 41 patients who underwent the surgical treatment and were followed-up for more than 12 months. The mean age of population was 64.4 years. 31 males and 10 females were included. Wide excision with following skin grafts or flaps for reconstruction (29 cases) was mostly performed, but amputation (12 cases) was also performed for cases with extremities where resection margin was difficult to obtain and cases with neural or vascular invasion. 8 patients underwent chemotherapy or radiotherapy after resection, and 33 underwent the operation only. Stages were classified by AJCC Classification, survival rate was calculated by Kaplan-Meier method and survival rate of groups was compared by Log-rank test. For the expectable prognostic factors related to survival rate, location of primary lesion, cause of disease, pathologic grade, staging, surgical method, additional anticancer therapy were examined and each survival rate was compared. Results: The average follow-up period was 65.2 (12-132) months. Thirty patients survived out of 41 patients till last follow up. The overall survival rate in 5 years was 77%. Three cases (7.3%) had local recurrence, and 7 cases (17.0%) had metastasis. The average period of recurrence from operation was 27 (18-43) months. Possible prognostic factors such as location of primary lesion, cause of disease, pathologic grade, staging, additional anticancer therapy showed no significant difference in survival rates. However, patients with amputation showed significantly lower survival rate than those with wide excision. Conclusion: In analysis the results of treating 41 cases of squamous cell carcinoma, the overall 5-year survival rate was 77%. And, among the several prognostic factors, only the surgical method was significant statistically.