Survival Time and Relative Risk of Death in Patients with Colorectal Cancer in an Iranian Population: a Cohort Study

Background and Colorectal cancer (CRC) is one of the most prevalent health problems in the world and Iran. This study aimed at determining the survival rate of patients with CRC and the factors influencing it in Iranian patients. A prospective cohort study was carried out in patients attending 10 state and private hospitals in Tehran during 2006-2011. In this study 1127 patients (totally 2570 individuals-year) were followed up every six months and the follow-up duration was from the definite time of CRC diagnosis until death (or censoring). Only 2% of the patients were censored. Data was analyzed using stata software, bivariate and multivariate analyses, and also Cox regression. The mean age of the patients was 53.5 ± 14 years old at the time of diagnosis. Most of the patients were older than 45 years of age (69.7%). The age at diagnosis was significantly different between men and women (P<0.03). The patients were 61.2% male and the rest were female. The rates of mortality in male and female were 96.9 and 83 in 100,000. After the diagnosis has been made 75%, 50%, and 25% had a survival rate of less than 2.72 years, 5.84 years, and longer than 13 years, respectively. In Cox model some variables including ethnicity, marital status, cancer grade, family history of caner, and smoking were the main determinants of survival. The mean survival time was 5.8 years after diagnosis has been made which shows more improvements compared to previous studies. This study provides some information on CRC survival rate so that action plans could be designed to prevent and control this disease.