Colorectal cancer in Iran: Epidemiology and morphology trends.

Colorectal cancer is one of the most prevalent cancers in different countries, including Iran. No comprehensive study has been done in the country for colorectal cancer, but information on the incidence and trends is essential to planning. This study aimed to evaluate the occurrence and morphology of colorectal cancer and its trend in Iran. This study was conducted using data from the national cancer registry system in Iran from 2003-2008. We used joinpoint regression analysis for assessing incidence time trends and morphology change percentage. Of all cases of colorectal cancer, 61.83 % were colon cancer, 27.54 % rectal cancer, 7.46 % rectosigmoid cancer, and 3.10 anal cancer. The most common histological types with the frequencies of 80.85 % was related to adenocarcinoma, NOS. The Annual percentage changes (APC) in ASIR for colorectal cancer significantly increased in both men and women. APC in ASIR was 13.7 (CI: 10.5-17.1) in women and 16.4 (CI: 12.4-20.5) in men. APC of adenocarcinoma in villous adenoma showed significant declining trend (p<0.05), while APC of adenocarcinoma, NOS had a constant trend. The incidence of the cancer in recent years has increased in Iran because of changes in lifestyle and diet. Therefore, further studies are necessary to detect the cause of this cancer and perform preventive measures.