What is Colorectal Cancer?

About the Colon and Rectum

The colon and rectum make up the large intestine. The colon makes up the first four to five feet of the large intestine and the rectum comprises the last several inches.

The colon takes partly digested food from the small intestine and continues the digestive process by removing water and other nutrients from the food and turning the remainder into waste. That waste then moves into the rectum and is passed out through the anus.

Colon_diagram

Understanding Colorectal Cancer

Billions of cells do different jobs throughout the body. Normal cells grow, divide and organize in an orderly way. Cells die and are replaced by new cells continuously.

A tumor develops when cells in the body begin to divide and change without order or control. If cells keep dividing uncontrollably, a mass of tissue forms into a growth or tumor.

Not all tumors are cancerous. Tumors that are not cancerous are considered benign. Malignant tumors are cancerous and can invade nearby tissue and spread to other parts of the body.

Colorectal cancers almost always start as benign growths called polyps, in the wall of the colon. Polyps are common, especially in people over age 50. Polyps that become cancerous typically progress slowly, taking up to 10 years to develop into cancer.

Once a polyp becomes cancerous, cancer cells can spread from the colon or the rectum to the lymph nodes, liver and lungs. Most polyps can be detected and removed before they become cancerous.