The name of this tumor is derived from the Latin terms for the sections of the large intestine where the neoplasm occurs: the colon is the bowel, and the rectum is the straight section at the end of the intestine. Colorectal cancer is the fourth most frequently occurring oncological disease in the world, and the second most common in countries with highly developed medical systems. There is at the present time a clear upward trend in morbidity. This is thought to be related to the introduction of early diagnostic techniques, increased life expectancy, aspects of the gene pool, the growing influence of external adverse factors, and changing lifestyles.
The disease is more often found in people in late middle age and the elderly: about 85% of all patients are over the age of 55. According to some estimates, the risk of bowel cancer doubles for each decade of a person’s life. Colorectal cancer is very rarely identified at age 30 or under.