• Journal of the Korean Data and Information Science Society
• /
• v.10 no.1
• /
• pp.47-56
• /
• 1999

In this paper, for whole line ($0,\;{\infty}$), the estimation procedure of mean residual life function using product-limit estimator is studied with asymptotic properties. And also, the small sample properties of proposed estimator of MRLF are investigated through Monte Carlo study and compared with Kaplan-Meier type estimator.

• Journal of the Korean Data and Information Science Society
• /
• v.1
• /
• pp.47-57
• /
• 1990

A method which determines the number of replications in the simulation is proposed, particularly for small-sample comparison of estimators. This method takes the smallest number of replications that makes the difference of mean square errors be statistically significant and provides an efficient algorithm for calculating the standard error of the mean square error. Two examples are illustrated, the first one is on comparison of mean and median ; the second, the Kaplan-Meier type and Buckley-James type estimators of a quantile function with censored data.

• Journal of Korean Society for Quality Management
• /
• v.22 no.3
• /
• pp.111-118
• /
• 1994

In this paper we propose a parametric and a nonparametric small sample estimators for the mean residual life (MRL) under the random censorship model using the partial moment approximation. We also compare the proposed nonparametric estimator with the well-known nonparametric MRL estimator based on Kaplan-Meier estimator of the survival function, and present the efficiency of the nonparametric method relative to the Weibull model for small samples.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.9
• /
• pp.4079-4083
• /
• 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
• /
• v.15 no.19
• /
• pp.8483-8488
• /
• 2014

Background: Breast cancer is the most common cancer and the second most common cause of cancer-induced mortalities in Iranian women, following gastric carcinoma. The survival of these patients depends on several factors, which are very important to identify in order to understand the natural history of the disease. Materials and Methods: In this retrospective study, 313 consecutive women with pathologically-proven diagnosis of breast cancer who had been treated during a seven-year period (January 2006 until March 2014) at Towhid hospital, Sanandaj city, Kurdistan province of Iran, were recruited. The Kaplan-Meier method was used for data analysis, and finally those factors that showed significant association on univariate analysis were entered in a Cox regression model. Results: the mean age of patients was $46.10{\pm}10.81$ years. Based on Kaplan-Meier method median of survival time was 81 months and 5 year survival rate was $75%{\pm}0.43$. Tumor metastasis (HR=9.06, p=0.0001), relapse (HR=3.20, p=0.001), clinical stage of cancer (HR=2.30, p=0.03) and place of metastasis (p=0.0001) had significant associations with the survival rate variation. Patients with tumor metastasis had the lowest five-year survival rate (37%)and among them patients who had brain metastasis were in the worst condition (5 year survival rate= $11%{\pm}0.10$). Conclusions: Our findings support the observation that those women with higher stages of breast malignancies (especially with metastatic cancer) have less chance of surviving the disease. Furthermore, screening programs and early detection of breast cancer may help to increase the survival of those women who are at risk of breast cancer.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.6
• /
• pp.3891-3895
• /
• 2013

The purpose of this study was to evaluate the association of expression of ${\alpha}5{\beta}1$-integrin with clinicopathologic features and prognosis in cervical cancer. Levels of ${\alpha}5{\beta}1$-integrin in normal cervical mucosa and cervical cancer tissue were detected with immunohistochemistry. Survival analysis by the Kaplan-Meier method was performed to assess prognostic significance. ${\alpha}5{\beta}1$-integrin expression was detected in 84.6% (143/169) cervical cancer samples, significantly different from that in normal cervical mucosa (P < 0.05). Positive expression rates of ${\alpha}5{\beta}1$-integrin in patients with poor histologic differentiation, lymph node metastasis, and recurrence were elevated. Using Kaplan-Meier analysis, a comparison of survival curves of low versus high expression of ${\alpha}5{\beta}1$-integrin revealed a highly significant difference in human cervical cancer cases (P < 0.05), suggesting that overexpression of ${\alpha}5{\beta}1$-integrin is associated with a worse prognosis.The ${\alpha}5{\beta}1$-integrin promotes angiogenesis and associates with lymph node metastasis, vascular invasion and poor prognosis of cervical cancer. The current study indicated that ${\alpha}5{\beta}1$-integrin may be an independent prognostic factor for cervical cancer patients.

• Journal of Korean Traditional Oncology
• /
• v.24 no.2
• /
• pp.1-11
• /
• 2019

Objectives : We investigated whether a single center nutrition screening tool (Kyunghee Neo Nutrition Risk Screening, KNNRS) can predict survival in patients with metastatic cancer. Methods : We retrospectively reviewed data of inpatients with metastatic cancer from April 2016 to August 2019. Data on demographic and clinical parameters were collected from electronic medical records, and overall survival was estimated using the Kaplan-Meier method. Stepwise Cox regression analysis was used to determine factors associated with survival. Patients with a KNNRS score of 0 to 3 were classified as "no-risk", 4 to 10 as "low-risk", and 11 to 20 as "high-risk". Results : Total 105 patients were included in the study. According to nutritional screening at baseline, 25 patients (23.8%, median age 57.0) were classified as ""no risk"" group; 80 patients (76.2%, median age 68.5) as "low risk" group; No patients as "high risk" group. Predictors of survival were Eastern Cooperative Oncology Group Performance Status score of 3 or 4 (hazard ratio [HR] = 1.93; 95% confidence interval [CI] = 1.21-3.10), hemoglobin less than 10 g/dL (HR = 1.97; 95% CI = 1.25-3.10) and C-reactive protein more than 1.0 mg/dL (HR = 1.95; 95% CI = 1.21-3.13). Kaplan-Meier survival analysis showed significant differences in the survival between KNNRS groups: ""no risk"" group: 6.1 ± 1.4 months (95% CI = 3.37-8.83); ""low risk"" group: 3.4 ± 0.9 months (95% CI = 1.5-5.37). Conclusions : Nutritional status according to KNNRS wasn't significant predictor of survival for patients with metastatic cancer. Improvement of KNNRS score thresholds is needed.

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

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

• Journal of Korean Neurosurgical Society
• /
• v.52 no.4
• /
• pp.334-338
• /
• 2012

Objective : We compared the survival time between patients with multiple gamma knife radiosurgery (GKRS) and patients with a single GKRS plus whole brain radiation therapy (WBRT), in patients with multiple metachronous brain metastases from lung cancer. Methods : From May 2006 to July 2010, we analyzed 31 patients out of 112 patients who showed multiple metachronous brain metastases. 20 out of 31 patients underwent multiple GKRS (group A) and 11 patients underwent a single GKRS plus WBRT (group B). We compared the survival time between group A and B. Kaplan-Meier method and Cox proportional hazards were used to analyze relationship between survival and 1) the number of lesions in each patient, 2) the average volume of lesions in each patient, 3) the number of repeated GKRS, and 4) the interval of development of new lesions, respectively. Results : Median survival time was 18 months (range 6-50 months) in group A and 6 months (range 3-18 months) in group B. Only the average volume of individual lesion (over 10 cc) was negatively related with survival time according to Kaplan-Meier method. Cox-proportional hazard ratio of each variable was 1.1559 for the number of lesions, 1.0005 for the average volume of lesions, 0.0894 for the numbers of repeated GKRS, and 0.5970 for the interval of development of new lesions. Conclusion : This study showed extended survival time in group A compared with group B. Our result supports that multiple GKRS is of value in extending the survival time in patients with multiple metachronous brain metastases, and that the number of the lesions and the frequency of development of new lesions are not an obstacle in treating patients with GKRS.