NAGHIBZADEH-TAHAMI A, YAZDI FEYZABADI V, KHANJANI N, ASHRAFI-ASGARABAD A, ALIZAEH H, BORHANINEJAD VR, MORADI-JOO M, ZEINALI M, ZAHEDI MJ, AGHAEE-AFSHAR M, HAGHDOOST AA. Can Opium Use Contribute to a Higher Risk of Colorectal Cancers? A Matched Case-control Study in Iran. Iran J Public Health. 2016;45(10):1322-1331.