The first step in treating colorectal cancer is usually an operation to remove the tumor. Sometimes a simple operation can be done during a colonoscopy or sigmoidoscopy to remove small polyps and a small amount of tissue surrounding them. But 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.

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 colorectal cancer. Your doctor may use one of the following types of surgery:

• Polypectomy. When the cancer is still just in a polyp, it will be removed during colonoscopy or sigmoidoscopy.
• Resection. If your cancer is larger, your doctor will remove the cancer and a small amount of healthy tissue. The healthy ends of the colon or rectum are then sewn back together. During this operation, your doctor will also remove some of your lymph nodes for testing.
• Resection and colostomy. Sometimes it isn't possible to rejoin the ends of the colon or rectum after the cancer is removed. Your doctor will do a colostomy and make 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.

Sometimes it is possible to have laparoscopic surgery to remove the cancer. This is surgery where very small incisions are made in the belly. A tiny camera and special instruments are used to remove the cancer. For the best results, it is important to have an experienced surgeon.⁵

Even after removing all the cancer that can be found with surgery, your doctor may say you need other treatment. This may be chemotherapy, radiation, or both (chemoradiation).

Chemotherapy uses medicines—given either as pills or through a needle—to destroy cancer cells throughout the body. Several medicines are often used together. Research studies continue to look for the best combinations of medicines. Your doctor will recommend treatment based on the type and stage of cancer that you have.

Radiation therapy, which uses X-rays to destroy cancer cells, is standard treatment for some types of cancer in the rectum. Radiation therapy is often combined with surgery or chemotherapy. Radiation may be given from a machine outside the body that targets the cancer (external radiation). Or it may be given inside the body, with radiation sealed in seeds or wires (internal radiation).

Compared to surgery alone, radiation therapy given before surgery for rectal cancer may reduce the risk that the cancer will return and may help you live longer.⁶

Side effects of treatment

Surgery, chemotherapy, or radiation can have serious side effects. But your medical team will help you manage the side effects of your treatment. This may include medicines for pain following surgery or medicines to control nausea and vomiting if you have chemotherapy.

Talk with your doctor and medical team about your side effects. Some side effects, such as pain or tingling in your hands or feet that gets worse (peripheral neuropathy), may be a sign that your medicines need to be changed.

For tips on how to manage side effects at home, see the Home Treatment section of this topic.

Additional information about colon and rectal cancer is provided by the National Cancer Institute at www.cancer.gov/cancertopics/types/colon-and-rectal.

Ongoing treatment

After your treatment, you will need regular checkups by a family doctor, general practitioner, medical oncologist, radiation oncologist, or surgeon, depending on your case. During your follow-up visits you may have one or more of these tests:

• Physical exams. How often you have these depends on your general health and the type of colorectal cancer you have. In general, you will see your doctor several times a year for 3 to 5 years and then return to once-a-year checkups.
• Colonoscopy, to inspect the inner surface of your colon and rectum for new problems
• Carcinoembryonic antigen (CEA) and other blood tests, to check the success of your treatment and find out whether the cancer has returned
• CT scan or MRI, to see if the cancer has spread to other organs

Treatment if the condition gets worse

Colorectal cancer comes back after surgery in about half of people who have surgery to remove the cancer.⁶ The cancer may be more likely to come back after surgery if it was not discovered in an early stage. Cancer that has spread or comes back is harder to treat, but sometimes treatments are successful. For more information, see the topic Colorectal Cancer, Metastatic and Recurrent.

What to think about

After you have had colorectal cancer, your chances of having it again go up. It's important to continue to see your doctor and be tested regularly to help find any returning cancer or new polyps early.

Clinical trials are designed to find better ways to treat people with cancer and are based on the most current information. Some people who meet the criteria for participation choose to enroll in such clinical trials.