A competing risks cure frailty model: An application to relapse-free survival of breast cancer patients

Abstract

In competing risks cure models, if there is unobserved heterogeneity among susceptible patients, application of the methods that do not consider this heterogeneity, may lead to invalid results. Therefore, this study aimed to introduce a model to cover the above properties of survival studies. We introduced a unified model by combining a parametric mixture cure gamma frailty model and vertical modeling of competing risks. We obtained estimates of parameters by an iterative method and Laplace transform technique. Then, we calculated the cumulative incidence functions (CIFs) and related confidence bounds by using a bootstrap approach. We conducted an extensive simulation study to evaluate the performance of the proposed model. The results of the simulation study showed the superior performance of our proposed competing risks cure frailty model. Finally, we applied the proposed method to analyze a real dataset of breast cancer patients.