Background: Colorectal cancer is a main leading cause of cancer death in western countries. Although many
studies have been conducted on incidence trends all over the world in recent years, information regarding changes
in incidence of colorectal cancer in Iran is insufficient. The present study of colorectal cancer in the west of Iran
during recent years was therefore performed. Materials and Methods: The registered data for colorectal cancer
cases in National Cancer Registry System were extracted from the Ministry of Health and Medical Education,
Center for Disease Control and Management. The codes from 18-21 among cancers were selected for colon and
rectum cancers. Incidence rates were standardized directly using WHO population. The significance of incidence
rate trends during 2000-2005 was tested through Poisson regression. Results: 762 cases of colorectal cancer were
observed during 6 years in this region, with a gender ratio of men to women of 1.2. It increased from 65 cases
in 2000 to 213 cases in 2005 or from 1.5 per100,000 per persons per year to 4.8. Significant increasing trends
were evident in Kermanshah and Hamadan provinces; however, change did not reach significance in Ilam and
Kurdistan provinces. Conclusions: Colorectal cancer has an increasing trend in the west of Iran. Although it
seems that the increasing rate of colorectal cancer is due to increasing of cancer risk factors, some proportion
may be related to the improvement of surveillance systems in Iran.