Application of Bayes method in determining of the risk factors on the survival rate of gastric cancer patients

Abstract

Introduction: Gastric cancer is one of the most common cancers in the world. The classical methodssuch as Cox regression and parametric models are used in most medical researches that their aims is thesurvival distribution survey, although the Bayes models have some advantages in compared with theclassical models. The present study was performed to analyze the survival rate of patients who had gastriccancer and were under treatment in the gastroenterology ward of Taleghani hospital, in Tehran usingBayes models. Weibull distribution was used for modeling in the study .Material and Methods: This study was a cohort study and performed in the gastroenterology ward ofTaleghani hospital by using gastric cancer patient's data from January 2003 to December 2007.178patients were enrolled to the study and their information was collected through telephone contacts. Thesurvival rate of patients were analyzed using Bayes Weibull models by considering variables such as ageof diagnosis, gender, tumor size, metastasis of other lymph. For determining of the risk factors on thesurvival of patients, was used Weibull model in the case that interval censoring. Data analysis was carriedout using Winbugs software and significant levels were considered 0.05 .Results: The results showed survival rate are dependent on the age of diagnosis and tumor size. Thosepatients who had early diagnosis, the rate of survival was greater. In addition, he patients who had smallertumor size, their survival rate was greater .Conclusion: Considering to classical models are based on normal approximation and applicable for bigsamples, Bayes methods are emphasized for small to medium samples. The results of this study showedthat the Bayesian Weibull model is a suitable model. This study also showed that age of diagnosis andtumor size of patients is important factors in regard to the survival rate of these patients. As a result, ifgastric cancer is diagnosed early, the relative risk of death would reduce