Most cases of colorectal cancer are caused by adenomatous polyps. Adenomatous polyps are asymptomatic in most cases. The malignant transformation process takes a relatively long time. Malignant transformation of adenomatous polyps (adenoma-carcinoma sequence) takes 5 to 10 years due to multiple genetic mutations. Adenomatous polyps are relatively asymptomatic. They are present in 25% of people over the age of 50 and their prevalence increases with age. Most polyps (90%) can be removed during a colonoscopy, eliminating the need for surgery.