Prognostic Factors for Survival in Patients with Colorectal Cancer in Iran between 2004-2015: Competing Risks Regression Analysis with Generalized Weibull Model

Abstract

Background: Colorectal cancer constitutes one of the most common causes of cancer mortality worldwide. The incidence of this malignancy has risen in Iran during the last years. This study aims to estimate the survival of colorectal cancer patients and its prognostic factors using parametric competing risks model. Methods: In a retrospective study, we used data from 1060 patients with colorectal cancer in the cancer registry of the Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, from 2004 to 2015. Analysis was performed using parametric competing risks model with Weibull distribution. R software was used for all analyses with significance level set at 0.05. Results: In total, 380 patients (35.8%) had died due to colorectal cancer, 49 patients (4.6%) had died for other causes, and 631 patients (59.5%) survived until the end of the study period. Mean survival for the 1060 patients was 59.96 ± 1.46 months with a median of 45.5 months. Multivariable analysis revealed factors such as age at diagnosis and body mass index (BMI) to significantly affect death by colorectal cancer (p < 0.001). Conclusion: According to the findings of the generalized Weibull parametric competing risks model, only age at diagnosis and BMI were factors influencing the survival of colorectal cancer patients in this study.

Keywords

• Survival Analysis
• Competing risk
• Colorectal cancer
• Weibull model