• Communications for Statistical Applications and Methods
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• v.26 no.5
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• pp.445-461
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• 2019

It is possible that data are not always fitted with sufficient precision by the existing distributions; therefore this article presents a methodology that enables the use of families of asymmetric distributions as alternative probabilistic models for survival analysis, with censorship on the right, different from those usually studied (the Exponential, Gamma, Weibull, and Lognormal distributions). We use a more flexible parametric model in terms of density behavior, assuming that data can be fit by a distribution of stable distribution families considered unconventional in the analyses of survival data that are appropriate when extreme values occur, with small probabilities that should not be ignored. In the methodology, the determination of the analytical expression of the risk function h(t) of the $L{\acute{e}}vy$ distribution is included, as it is not usually reported in the literature. A simulation was conducted to evaluate the performance of the candidate distribution when modeling survival times, including the estimation of parameters via the maximum likelihood method, survival function ${\hat{S}}$(t) and Kaplan-Meier estimator. The obtained estimates did not exhibit significant changes for different sample sizes and censorship fractions in the sample. To illustrate the usefulness of the proposed methodology, an application with real data, regarding the survival times of patients with colon cancer, was considered.

• STI Policy Review
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• v.9 no.1
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• pp.55-76
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• 2018

This study analyzed the effect of the government R&D subsidy program on long-term firm survival. In order to estimate the average treatment effect for the treated group, we used the survival analysis and matching method by constituting a comprehensive dataset of more than 90,000 observations. The analysis results show that the government R&D subsidy has a negative impact on long-term firm survival. In particular, not only the subsidy does not have a statistically significant effect on firm survival in the relatively short-term, the survival probability of the subsidized firms is statistically significantly lower than the non-subsidized firms after six years. These results can be seen as weakening the justification of government R&D support. There may be problems in the subsidy policy itself and the process of selection of subsidy awardees; however, the more fundamental problem is that the subsidy policy is concluded as the one-time event. Admittedly, it would be difficult for the government to precisely manage the subsidized projects over a long term period. However, in the case of a project in which short-term performance is detected, it would be necessary to provide a step-by-step support to strengthen the firm's competitiveness through further support and continuous development of performance. Of course, mid- and long-term evaluations of subsidy support policy should be performed in parallel with such phased support.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5381-5384
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• 2012

Background and Aim: Cholangiocarcinoma (CCA) is an uncommon malignancy of the bile duct, occurring in nearly 2 out of 100,000 people. It is a type of adenocarcinoma that originates in the mucous glands of the epithelium, or surface layers of the bile ducts. The aim of this study was to evaluate the clinical features, diagnostic results and factors associated with survival, morbidity and mortalityof cholangiocarcinoma cases in Iranian patients. Method: In this retrospective study the hospital medical records of 283 patients with a primary or final diagnosis of cholangiocarcinoma who had been admitted to gastroenterology ward of our hospital from 2004 to 2011 were retrospectively reviewed. Results: 283 patients (180 male, 63%, and 103 female, 38.6%) with a mean age of $59.7{\pm}14.4$ years were studied. The most frequent symptoms were painless jaundice (190, 66.9%), abdominal pain (77, 27%), pruritus 133 (46.8%) and weight loss (169, 59.5%). The most frequent associated risk factors and diseases were as follows: gallstones (72, 25.4%), diabetes (70, 24.6%), HBV infection (52 (18.3%), HCV infection 43 (15%), primary sclerosing cholangitis (16, 5.6%) and smoking (120, 42.3%). The most frequent type of cholangiocarcinoma in ERCP and MRCP was hilar. The mean survival time was $7.42{\pm}5.76$ months. Conclusion: The mean survival time in our study was lower than one year. Moreover the most frequent risk factors and associated diseases were smoking, gallstones and diabetes. Painless jaundice, abdominal pain and weight loss were the most clinical features related to cholangiocarcinoma. Additionally survival time did not correlate with risk factors, associated diseases and clinical presentations, but was linked to biliary metallic stenting and surgery.

• Journal of Preventive Medicine and Public Health
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• v.23 no.1 s.29
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• pp.77-86
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• 1990

Between 1977 and 1987, 20 patients with mesothelioma were treated at Severance Hospital. Data was gathered from medical charts at the time of hospitalization of mesothelioma patients and from a follow-up questionnaire by mail or telephone. The results acquired were as follows : 1. Among the 20 patients, 11 men and 9 women with mesothelioma were identified. The mean age at hospitalization was 47 years and 11 mesothelioma patients were known or presumed to be dead during the different observation periods. 2. Only one mesothelioma patient had a definite history of occupational asbestos exposure. 3. The sites of origin of mesothelioma were the pleura(13), peritoneum(2), pericardium(2), mediastinum (2), and pelvis(1). Common symptoms included dyspnea, chest pain, abdominal distension, etc. 4. Pathologically, mesotheliomas were divided into 14 malignant types and 6 benign types ; and histologically, 8 fibrous mesotheliomas and 3 epithelial mesotheliomas were shown. 5. There was a statistically significant difference in survival rate according to pathologic type and smoking status. In the groups with malignant mesothelioma, 50% survival time from first symptoms was 18 months and that from diagnosis was 11 months. Also, 75% survival time from diagnosis was 6 months in the smoking groups and 19 months in the non-smoking groups.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.1
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• pp.331-334
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• 2014

There is a scarcity of reports addressing patients with multiple primary malignancies (MPM), especially for Chinese cses. The aim of this study was to present a detailed analysis of Chinese patients presenting with at least two primary malignancies. Particularly, the clinical characteristics and survival between synchronous and metachronous MPM were compared. Out of 6,545 cases, 72 patients (1.1%) including 39 males (54.2%) and 33 females (45.8%) were diagnosed as MPM, giving a male: female sex ratio of 1.2:1. Of these, there were 16 (22.2%) cases of synchronous MPM (7 males, 9 females), 55(76.4%) metachronous (31 males, 24 females), and 1 "mixed form". For first tumor diagnosis time, synchronous MPM patients generally presented later than the metachronous cases. The top three sites for malignancies with metachronous MPM were colorectum, head and neck, and lung, while for synchronous they were lung, colorectum and breast. Among MPM patients, the median survival time was 15.7 years and the 5-year survival was 56%, and there was statistical difference in MPM categories (P < 0.05). The median survival time was 17.3 years and 3.8 years for metachronous and synchronous MPM patients, respectively. In comparison with synchronous MPM patients, those metachronous had a longer survival. This studies increase understanding of the clinical features of Chinese MPM patients and suggest that those presenting with metachronous cancers have a higher incidence and a better prognosis.

• Journal of Gastric Cancer
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• v.11 no.1
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• pp.38-45
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• 2011

Purpose: Bone metastasis from stomach cancer occurs only rarely and it is known to have a very poor prognosis. This study examined the clinical characteristics and prognosis of patients who were diagnosed with stomach cancer and bone metastasis. Materials and Methods: The subjects were 19 patients who were diagnosed with stomach cancer at Hanyang University Medical Center from June 1992 to August 2010 and they also had bone metastasis. The survival rate according to many clinicopathologic factors was retrospectively analyzed. Results: 11 patients out of 18 patients (61%) who received an operation were in stage IV and the most common bone metastasis location was the spine. Bone scintigraphy was mostly used for diagnosing bone metastasis and PET-CT and magnetic resonance imaging were used singly or together. The serum alkaline phosphatase at the time of diagnosis had increased in 12 cases and there were clinical symptoms (bone pain) in 16 cases. Treatment was given to 14 cases and it was mostly radiotherapy. There were 2 cases of discovering bone metastasis at the time of diagnosing stomach cancer. The interval after operation to the time of diagnosing bone metastasis for the 18 cases that received a stomach cancer operation was on average $14.9{\pm}17.3$ months and the period until death after the diagnosis of bone metastasis was on average $3.8{\pm}2.6$ months. As a result of univariate survival rate analysis, the group that was treated for bone metastasis had a significantly better survival period when the bone metastasis was singular rather than multiple, as compared to the non-treatment group, yet both factors were not independent prognosis factors on multivariate survival analysis. Conclusions: An examination to confirm the status of bone metastasis when conducting a radio-tracer test after the initial diagnosis and also after an operation is needed for stomach cancer patients, and bone scintigraphy is the most helpfully modality. Making the diagnosis at the early stage and suitable treatments are expected to enhance the survival rate and improve the quality of life even for the patients with bone metastasis.

• 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.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.11
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• pp.6899-6903
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• 2013

Background: Prevalence is a statistic of primary interest in public health. In the absence of good follow-up facilities, it is difficult to assess the complete prevalence of cancer for a given registry area. Objective: An attempt was here made to arrive at complete prevalence including limited duration prevalence with respect to selected sites of cancer for India by fitting appropriate models to 1, 3 and 5 years cancer survival data available for selected population-based registries. Materials and Methods: Survival data, available for the registries of Bhopal, Chennai, Karunagappally, and Mumbai was pooled to generate survival for breast, cervix, ovary, lung, stomach and mouth cancers. With the available data on survival for 1, 3 and 5 years, a model was fitted and the survival curve was extended beyond 5 years (up to 35 years) for each of the selected sites. This helped in generation of survival proportions by single year and thereby survival of cancer cases. With the help of survival proportions available year-wise and the incidence, prevalence figures were arrived for selected cancer sites and for selected periods. Results: The prevalence to incidence ratio (PI ratio) stabilized after a certain duration for all the cancer sites showing that from the knowledge of incidence, the prevalence can be calculated. The stabilized P/I ratios for the cancer sites of breast, cervix, ovary, stomach, lung, mouth and for life time was observed to be 4.90, 5.33, 2.75, 1.40, 1.37, 4.04 and 3.42 respectively. Conclusions: The validity of the model approach to calculate prevalence could be demonstrated with the help of survival data of Barshi registry for cervix cancer, available for the period 1988-2006.

• Annals of dermatology
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• v.30 no.6
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• pp.668-675
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• 2018

Background: Drug survival, defined as the time until discontinuation, is a parameter reflecting real-world therapeutic effectiveness. Few studies have examined the influence of economic factors on the drug survival of biologic agents for psoriasis, particularly in Asian countries. Objective: To determine the drug survival for ustekinumab in real-life settings and investigate the factors affecting drug survival for psoriasis patients in Korea. Methods: We evaluated 98 psoriasis patients who were treated with ustekinumab at a single center. We analyzed the efficacy and drug survival of ustekinumab. Cox proportional hazard analysis and competing risk regression analysis were performed to reveal the factors affecting the drug survival of ustekinumab. Results: The overall mean drug survival was 1,596 days (95% confidence interval [CI], 904~2,288). Among the 39 cessations of ustekinumab treatment, 9 (23.1%) patients discontinued treatment after experiencing satisfactory results. Multivariate Cox proportional hazard analysis revealed that paying on patients' own expense was the major predictor for the discontinuation of ustekinumab (hazard ratio [HR], 9.696; 95% CI, 4.088~22.998). Competing risk regression analysis modeling of discontinuation because of factors other than satisfaction of an event also revealed that ustekinumab treatment at the patient's expense (HR, 4.138; 95% CI, 1.684~10.168) was a predictor of discontinuation rather than satisfaction. Conclusion: The results of our study revealed that the cost of biologics treatment affects the drug survival of ustekinumab and suggested that economic factors affect the drug survival of ustekinumab treatment in Korea.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.3
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• pp.305-313
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• 2009

This paper provides a method for evaluating a residual life of water mains using a proportional hazard model(PHM). The survival time of individual pipe is defined as the elapsed time since installation until a break rate of individual pipe exceeds the Threshold Break Rate. A break rate of an individual pipe is estimated by using the General Pipe Break Model(GPBM). In order to use the GPBM effectively, improvement of the GPBM is presented in this paper by utilizing additional break data that is the cumulative number of pipe break of 0 for the time of installation and adjusting a value of weighting factor(WF). The residual lives and hazard ratios of the case study pipes of which the cumulative number of pipe breaks is more than one is estimated by using the estimated survival function. It is found that the average residual lives of the steel and cast iron pipes are about 25.1 and 21 years, respectively. The hazard rate of the cast iron pipes is found to be higher than the steel pipes until 20 years since installation. However, the hazard rate of the cast iron pipes become lower than the hazard rates of the steel pipes after 20 years since installation.