Colorectal cancer refers to cancer that starts in either the colon or the rectum of the digestive system. After food is eaten, it travels to the stomach where it is partly broken down and then sent to the small intestine. Most of the food’s nutrients are absorbed in the small intestine as they travel to the colon. The colon absorbs water and remaining nutrients from the food. It also stores waste matter (stool), which eventually moves from the colon into the rectum. From there, stools pass out of the body through the opening called the anus.
The walls of the colon and rectum are made up of layers of tissues. Colorectal cancer starts in the inner layer and can grow through some or all of the other layers. The stage of a cancer greatly depends on how deep it goes into these layers. Most colorectal cancers start as a polyp -- a growth that starts in the lining and grows into the center of the colon or rectum. Removing a polyp early may keep it from becoming cancer.
There are four main types of treatment for colorectal cancer:
Depending on the stage of your cancer, two or more types of treatment may be used at the same time, or used one after the other.