An evulation of 5-year survival of metastatic colon and rectal cancer patients using cumulative incidence models

  Introduction: In the presence of competing risks, using of cumulative incidence function is important from the health economic evaluation point of view. This study aimed to use this function for determining the risk factors of competing events of colon and rectal cancers in metastatic patients.   Materials and Methods: In this survival study, data including age at diagnosis, sex, marital status, Body Mass Index (BMI), morphology of cancer, tumor size, tumor grade and pathological stage were gathered from the Research Center for Gastroenterology and Liver Diseases, Shaheed Beheshti University of Medical Sciences, Tehran for 94 metastatic colorectal cancer patients. Using a regression model based on the cumulative incidence function, parameters and tests of significance were obtained utilizing the R 2.13.1 software.   Results: Five-year survival for metastatic patients with colon and rectal cancer, were 46.79% and 65.58% respectively, and the cumulative incidences were computed as .8 and 1.0 during a 100 months period, respectively. In the univariate and multivariate model, marital status in patients with colon cancer and in the univariate model, BMI and morphology were significant risk factors for rectal cancer.   Conclusion: Using of modeling based on cumulative incidence function is recommended as a model to study the risk factor of colon and rectal cancers due to its optimal characteristics.