Cox Models Survival Analysis Based on Breast Cancer

Background: The aim of this study is to evaluate the association between different treatments and survival time of breast cancer patients using either standard Cox model or stratified Cox model. Methods: The study was conducted on 15830 women diagnosed with breast cancer in British Columbia, Canada. They were divided into eight groups according to patients ’ ages and stage of disease Either Cox’s PH model or stratified Cox model was fitted to each group according to the PH assumption and tested using Schoenfeld residuals. Results: The data show that in the group of patients under age 50 years old and over age 50 with stage Ι cancer, the highest hazard was related to radiotherap