Incidence trends of colorectal cancer in Iran during 2000-2009: A population-based study

Background: As the third leading cause of death, cancers have a special place in the Iranian health system. Several studies have been done in some regions of the country with few years of follow-ups, but this was the first standardized study to investigate the incidence trends of colorectal cancer in Iran in a one-decade period. Methods: The registered data for colorectal cancer cases in National Cancer Registry System were extracted from the Center for Disease Control & Management of Ministry of Health. The codes from 18 to 21 among cancers were selected for colon and rectum cancers. Incidence rates were directly standardized, using WHO population. The significance of incidence rate trends was tested through Poisson regression. Results: In this study, 36,650 cases of colorectal cancer were observed for 10 years in Iran, which increased from 813 cases in 2000 to 6,210 cases in 2009. Gender ratio of men to women was 1.39. Significant increasing trends of colorectal cancer were observed during the period of the study. The standardized incidence rate increased from 1.6 per 100,000 persons per year in 2000 to 11.3 in 2009 in males (p<0.001), and it increased from 1.6 per 100,000 persons per year in 2000 to 10.9 in 2009 in females (p<0.001). Conclusion: Colorectal cancer has an increasing trend in Iran. The rising trend of colorectal cancer as well as other types of cancers is partially due to improvement in cancer registry systems in the early years of registry. Moreover, westernized lifestyle and an increase in environmental risks could explain this rising trend.