Iranian Journal of

Background and Objectives: Colorectal cancer is the fourth leading cause of cancer death worldwide.  Annually 1430000 cases would be diagnosed and half of these people would die of the disease. In Iran, colorectal cancer is the fifth common cancer among men and is the thirdamong women. This study was designed to estimate survival rates for patients with colorectal cancer and related factors.  

Methods: During the 1384 to 1388 years 24,807 patients diagnosed with colorectal cancer were recorded in the Cancer Registry of the Ministry of Health and Medical Education. Age, gender, marital status, education, occupation, place of residence, tumor diagnosis, the clinical and demographic factors in colorectal cancer as effective on survival entered in Aalen’s additive hazard model and diagram Aalen's was used to study the effects of these factors over time. R 3.2.0 software was used for data analysis.

Results: Stage of tumor had a significant association with survival rates. In this study 1 to 5 year survival rate for patients with stage II tumors, was 100%, 98%, 96%, 93% and 93% respectively and for patients with stage III tumors 99%, 97%, 94%, 90% and 84%, respectively.

Conclusion: In spite of using Cox model in survival analysis by many researchers, Aalen’s model may yield new insights in prognostic studies of survival time of patients with colorectal cancer over time. Our results suggest that early detection of patients in primary stage is important to increase survival.