Analyzing the Long-Term Survival of Patients with Colorectal Cancer: A Study Using Parametric Non-Mixture Cure Rate Models

Background: Colorectal cancer (CRC) is a heterogeneous disease that occurs in different parts of the gastrointestinal system. Objectives: This study aimed at analyzing the effects of risk factorsonsurvivalandcure fraction of patients withCRCin a population of Iranian patients, using parametric non- mixture cure rate model. Methods: This retrospective cohort study was conducted at Shiraz University of Medical Sciences on 512 patients with CRC. Patients were followed-up for 8 years, fromJanuary2009until February 2017. Stepwise selectionandparametric non-mixture cure ratemodel were used tofindthe risk factors of survival in patients with CRC. Akaike information criteriawasused to identify the best parametric non-mixture cure rate model in this study. Results: Staging III (OR = 0.41, 95% CI: 0.19 - 0.90, P = 0.026), staging IV (OR = 0.15, 95% CI: 0.04 - 0.50, P = 0.002), Perineural invasion (OR = 0.41, 95% CI: 0.21 - 0.92, P = 0.007), and lymph node ratio (OR = 0.94, 95% CI: 0.51 - 0.82, P = 0.002) had significant effects on cure fraction and survival of patients with CRC. Conclusions: Perineural invasion, Lymph node ratio, and American Joint Committee on Cancer (AJCC) staging should be assessed as an important factor in modeling survival analysis of patients with CRC. Patients who were in advanced stages of CRC should have received treatment and appropriate therapies given their shorter survival rates.