Colorectal cancer (CRC) is a major cause of morbidity and mortality worldwide. Countries with the highest incidence rates contain Australia, New Zealand, Canada, the United States, and parts of Europe. The countries with the lowest risk contain China, India, and parts of Africa and South America. Iran, as an intransition country, is meeting population aging and rising prevalence of the western lifestyle. Therefore, continuing rising burden of colorectal cancer (CRC) is reasonably awaited in future years, while its incidence and mortality rates are still relatively high in Iran. CRC is responsible for 8.4% of all cancers in Iran, where it is the third most common cancer in men and the fourth most common cancer in women, with standardized incidence rates of 8.1-8.3 and 6.5-7.5 per 100 000, respectively; moreover. Most cases of colorectal cancer occur sporadically. Although the etiology of colorectal cancer is multifactorial, genetic and epigenetic alterations of proto-oncogenes and tumor suppressor genes stay the fundamental mechanism of tumorigenesis.
Seyed Reza Kazemi Nezhad