The Application of Weibull Regression in the Study of Survival Patients Evolved by Gastric Cancer Referred to Imam Khomeini Hospital of Sari (Northern Iran)

Abstract: Background and purpose: The survival rate of gastric cancer patients has significantly increased during the last decades because of the advances in this type of cancer treatment. The purpose of the current study was to examine the survival levels of gastric cancer through Weibull regression and its affective causes. Materials and methods: In this research, the records and personal information of ۶۴۳ patients who were evolved by gastric cancer and referred to Imam Khomeini hospital of Sari (۲۰۰۷- ۲۰۱۳) were studied in order to determine their levels of survival. During the study, ۷۴ cases of patients were exempted from the study due to their defective data, and the data collected from ۵۶۹ cases were analyzed to obtain the results. In the current study, the impact of factors affecting Survival time was determined using the Weibull regression model. The analysis of data was performed using Stata statistical Software in ۰.۰۵ significance level. Results: The findings of the study showed that these patients were estimated to experience ۵ years of survival  probability equal to ۰.۷۵, ۰.۶۸, ۰.۵۴, ۰.۴۱, ۰.۳ during the time period November – December, ۲۰۱۳, the ۱, ۲, ۳, ۴ with a median survival  time equal to ۱۹ months, resulting in a survival mean equal to ۲۴.۴۹ months. Based on the Univariate and Multivariate analyses methods, some variables like: stage and metastasis were determined as the affective factors on the survival probability. (p-value <۰.۰۵)  Conclusion: In this study, it was then concluded that the life span of examined patients is very low in comparison with developed countries, which might be because of late reference or delayed diagnosis and the lack of facilities for treatment. Thus, the factors such as earlier diagnosis of the problem and screen methods could certainly influence and increase the patients' survival rate.

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Keywords: Gastric cancer , Survival analysis , Weibull regression