The first step in treating colorectal cancer is usually an operation to remove the tumor. Sometimes a fairly simple operation can be done during a colonoscopy or sigmoidoscopy to remove small polyps and a small amount of tissue surrounding them. However, in most cases a major operation, in which the cancer and part of the colon or rectum around it are removed, is needed. If cancer has spread to another part of your body, such as the liver, you may need more far-reaching surgery.

After the cancer has been examined under a microscope, it will be staged. Staging is a way for your doctor to tell how far, if at all, your cancer has spread. It also helps your doctor decide what your treatment should be.

There are several different types of staging systems, so it's important to ask your doctor to explain carefully what stage your cancer is in and what that means.

In general, the most common staging system describes colorectal cancer this way:

• Stage I: Your cancer has not spread beyond the inside of your colon or rectum.
• Stage II: Your cancer has spread into the muscle layer of your colon or rectum.
• Stage III: Your cancer has spread to one or more lymph nodes in the area.
• Stage IV: Your cancer has spread to other parts of your body, such as the liver, lung, or bones.

Cancers that have not spread beyond the colon or rectum may require only surgery. If the cancer has spread, you may need radiation therapy, chemotherapy, or both.

Initial treatment

You and your doctor will work together to decide what your treatment should be. You will consider your own preferences and your general health, but the stage of your cancer is the most important tool for choosing your treatment.

Surgery is almost always used to remove colon cancer. If the cancer is found early, you may need only a simple procedure, called a polypectomy, in which a doctor removes small polyps found in the colon or rectum during a colonoscopy or sigmoidoscopy.

For a larger cancer, more extensive surgery is needed to remove the cancer and part of the colon or rectum around it. This is called a bowel resection. During this operation, your doctor will also remove some of your lymph nodes for testing. The healthy ends of the colon or rectum are then sewn back together.

Sometimes it isn't possible to rejoin the ends, and a colostomy is needed. This creates an opening on the outside of your abdomen where waste can pass through into a colostomy bag. The colostomy may be temporary until your colon heals, or it may be permanent if the entire lower colon or rectum was removed. Very few people who have colorectal cancer need a permanent colostomy.