Incidence of colorectal cancer in Iran: A systematic review and meta-analysis

The incidence of colorectal cancer (CRC) is rising in Iran, but reports vary across different regions due to diverse methods and data sources. This study aimed to conduct a systematic review and meta analysis to provide an overview of the incidence rate of CRC and its trend among Iranians in various provinces.

A comprehensive literature search based on the Preferred Reporting Items for Systematic Reviews and Meta Analyses checklist was performed using national and international databases for papers published up to December 2023. CRC incidence rates were extracted from the numbers, crude rates, and age standardized rates (ASRs). A meta analysis was conducted to calculate the incidence rate and 95% confidence intervals (CIs) in subgroups of sex and province.

The initial database search retrieved 1287 papers, with 47 studies meeting the inclusion criteria after further screening. Overall, the trend of CRC incidence has been increasing, although a different pattern was observed in 2008. The pooled incidence rate of CRC was 8.46 (95% CI: 7.16-9.86) per 100,000 population before the publication of the annual continuous reports of the Iranian National Cancer Registry. The latest national data (2014-2017) indicated an ASR of approximately 15 per 100,000 population.

The incidence of CRC in Iran is lower than the global average. However, inconsistent cancer registration policies and gaps in registration have hindered the ability to establish a reliable trend of CRC incidence over time.