Increased Colorectal Cancer Incidence In Iran: A Systematic Review And Meta-Analysis

Roya DOLATKHAH, Tabriz University of Medical Sciences, Iran
DASTGIRI S. 1,2 , SOMI M. 3 , ASVADI KERMANI I. 1 , GHOJAZADEH M. 3 , ASGHARI JAFARABADI M. 4 , FARASSATI F. 5

1 Hematology and Oncology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
2 Tabriz Health Services Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
3 Liver and Gastrointestinal Disease Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
4 Road Traffic Injury Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
5 The University of Kansas Medical School-Molecular Medicine Laboratory, Kansas City, KS, USA

 
 
Purpose
Colorectal cancer is the third most common cancer in Iran. The increasing trend of colorectal cancer incidence in Iran and the close relationship with the geographical location are the underlying reasons for this study.
Methods
Eleven databases, including MEDLINE, EMBASE, SCOPUS, and four other databases, for articles in Persian were searched from April 2014 to October 2014. Additional data were obtained from an online survey of the Central Library of Tabriz Faculty of Medicine.
 In this systematic review and meta-analysis, we included studies reporting different measures of incidence, age-standardized incidence rates, and crude incidence rates. All rates (per 100,000 person-years) were standardized to the world standard population.
A preliminary review of the title and abstracts of these articles was used to exclude any that were clearly irrelevant. The full text review determined whether the article was relevant to our topic. A total of 39 studies  from different provinces and diverse areas of Iran, were analyzed in this study using comprehensive meta-analysis software. For accuracy studies, we used estimated rates for males and females with 95% confidence intervals. 
​Results
Age-standardized incidence rates were obtained based on the random effects model and were 8.16 (95%CI: 6.64 to 9.68) and 6.17 (95%CI: 5.01 to 7.32) for males and females, respectively. The random crude rates were 5.58 (95%CI: 4.22 to 6.94) for males and 4.01 (95%CI: 3.06 to 4.97) for females.
​Conclusions
Colorectal cancer incidence rates rise due to individual and environmental risk factors as well as improvement in the registry system and increase in access to health services. A more executed organized and structured system for collecting cancer data, in all cities and rural areas of the country, is an essential priority.
Funding sources
Hematology and Oncology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
Key Words
​Epidemiology; Incidence; Colorectal Cancer