Colorectal cancer (CRC) is the third most common cancers worldwide. Golestan province in Northeast of Iran was known as a high risk area for upper gastrointestinal cancers since 1970s. Recent reports suggested increasing trends in incidence of CRC in this region during last decades. We aimed to assess the incidence trends of CRC in Golestan province during 15 years, 2004-2018.

Data on cancer incidence in Golestan province during 2004-2018 were obtained from the Golestan population-based Cancer Registry (GPCR). The GPCR is a high-quality cancer registry and is a voting member of the international association of cancer registries (IACR). We calculated age standardized incidence rates (ASR) of CRC using the World standard population. The rates were calculated per 100,000 person-year. Estimated annual percent changes (EAPC) and 95% confidence intervals (95%CI) of the ASR were calculated for assessing time trends in the incidence rates of CRC.

Between 2004 and 2018, a total number of 32764 cancer cases were registered in the GPCR, of which 2794 (8.52% of all cancer) and were CRC. The mean (SD) age of CRC cases were 57.75 (16.41) years and of which 1556 (55.69 %) were male. The ASR (95%CI) of CRC was 13.72 (13.19-14.25) per 100000 person-year. The ASR of CRC in male and female were 15.59 and 11.9 per 100000 person-year, respectively. Our findings suggested significant increasing trends in incidence rates of CRC in total population (EAPC= 3.75; 95%CI: 0.44 to 7.14) as well as in male (EAPC= 3.91; 95%CI: 0.81 to 7.11) and female (EAPC= 3.65; 95%CI: 0.12 to 7.31).

Our findings suggested increasing trends the ASR of CRC in total population of Golestan as well as in male and female during 2004-2018. Further studies are warranted to clarify the role of risk factors in increasing trends of CRC incidence in Golestan, population.