Colorectal cancer (CRC) develops in the colon or the rectum, also known as the large intestine. Colorectal cancers have different characteristics based on their location within the colon or rectum. For example, tumors in the proximal (right) colon are more common among women and older patients, whereas distal (left) tumors are more common among men and younger patients. It usually takes about 10 to 20 years for CRC to develop. Most begin as a polyp, also known as a non-cancerous growth, which develops on the inner lining of the colon or rectum. An adenoma is the most common kind of polyp, which arises from glandular cells. Adenomas have the ability to become malignant, however more than 90% do not progress to invasive cancer. Cancer that develops in glandular cells is called adenocarcinoma, which comprises approximately 96% of all colorectal cancers.