Temporal and geographical variations in colorectal cancer incidence in Northern Iran 2004-2013

Colorectal cancer (CRC) is one of the most common cancers in the Golestan province, Northern Iran. The purpose of this study is to describe colorectal cancer incidence patterns and trends in the province 2004-2013.

Data on CRC cases were obtained from the Golestan Population-based Cancer Registry (GPCR). The GPCR is a high-quality cancer registry that collects data on primary cancers according to internationally accepted standard protocols. Age-standardized Incidence rates (ASR) were calculated and the 10-year trend quantified using the average annual percentage change (AAPC) from Joinpoint regressions.

The overall ASR of CRC were higher in men (14.8 per 100,000 person-years) and the urban populations (35.4), relative to women (11.5) and the rural populations (17.1), respectively. The overall incidence rate was observed to significantly increase 2004-2013 in men (AAPC = 7.3; 95%CI: 2.9-11.8) and women (AAPC = 6.6; 95%CI: 2.7-10.6). The analysis also showed that urban areas (AAPC = 8.1; 95%CI: 2.4-14.1) had a relatively more rapid increase in rates compared to rural areas (AAPC = 6.9; 95%CI: 2.2-11.7).

CRC incidence rates in Golestan have been rising during the most recent decade, with a higher incidence and more rapid increases among men and the urban populations. The underlying risk factors should be assessed in the context of developing CRC prevention interventions in Golestan.