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Cancer Control Research

Abstract

DESCRIPTION (provided by applicant): Often in cancer and other medical studies, the primary response variable is the time to the occurrence of some particular event of interest (e.g. relapse of cancer, death of the patient, etc.). This kind of data is called survival data. The goals of this proposed research are to develop and extend semiparametric Bayesian models and associated full Bayes and empirical Bayes methodologies for the analysis of survival data obtained from various biomedical studies. The semiparametric models and associated methods will be sophisticated enough to deal with survival data in the presence of complex censoring and irregular data- collection monitoring schemes, in the presence of missed clinic visits and with subjects at the risk of recurrent events of different types as well as failure from different causes. Semiparametric models are a popular compromise between the too restrictive parametric and too non-informative nonparametric models. A semiparametric model has a nonparametric part (an unknown function such as a baseline hazard or an intensity function) as well as a parametric part involving a few parameters, such as regression coefficients for explanatory variables. The available prior information on the nonparametric part will be summarized as a stochastic process, called a prior process. The available prior information on the parametric part will be modeled as a prior distribution. The methodology developed during this project will be useful for the analysis of recurrent events data, survival data with competing causes of failures, survival data from the studies with multiple event states par subject, longitudinal data measured via outcome-dependent irregular clinic visits and survival data from multiple quality of life events. Development of models, associated data analytic tools, related computer programs and codes for statistical packages, extensive simulation studies, and diagnostic tools for verifying the key modeling assumptions will play central roles in each specific aim. New and existing methods will be evaluated and compared using analysis of mainly cancer studies data from the published literature and from other sources such as the MUSC Hoolings Cancer Center.