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Treating colorectal cancer

Doctors have several ways of treating cancer of the colon or rectum, including surgery, chemotherapy and radiation.

If you've just been diagnosed with cancer of the colon or rectum, you should know this: Treatment is available—and improvements over the years have played a role in helping more people survive the disease.

The main treatments are surgery and chemotherapy. Others—such as radiation, targeted therapy, immunotherapy, ablation and embolization—may be used. What's best for you depends on the stage of your cancer (how far it has spread) and many other factors—including whether cancer affects the colon or rectum specifically.

Here's a look at common treatments, with information from the American Cancer Society (ACS) and the National Cancer Institute:


Cancers found just on the inner lining of the colon or rectum or in a polyp (a small piece of bulging tissue) are often removed through the anus with a colonoscope or other instruments. Surgery for tumors that have grown into the colon or rectal wall generally involves removing the cancer and part of the colon or the rectum along with nearby lymph nodes and sometimes other tissues.

For colon cancer: The surgery is called a colectomy and is done through an open abdominal incision or with the help of special instruments inserted through several small incisions.

For rectal cancer: Several surgical methods can be used, depending on the tumor's location. For example, surgery may remove only part of the rectum, the entire rectum or the anus. Surgery also is sometimes needed to remove nearby pelvic organs to which cancer has spread.

Once the cancer is removed, the surgeon will reconnect the healthy colon or rectum sections, if possible, so waste can leave the body in the usual way.

If the anus or lower colon is removed, a colostomy may be needed. For this procedure, the surgeon makes an opening to the outside of the body for waste to enter a collection bag. In other cases, a colostomy may be needed only long enough for the colon or rectum to heal from treatment.

Surgery may also be done to remove tumors that have spread to other parts of the body, such as the liver or lungs.

Side effects of surgery depend on factors such as the extent of the operation and the person's health before surgery. They may include infection, bleeding, blood clots, damage to nearby organs during surgery and adhesions (scar tissue that causes organs or tissues to stick together). Some types of surgery may also cause sexual problems in men.


Chemotherapy uses cancer-fighting drugs given by mouth or injected in a vein. Treatments are given in cycles lasting several weeks, with breaks in between. Chemotherapy is often used:

  • After colon or rectal surgery to destroy any cancer cells that remain or that may have left the main tumor.
  • Before surgery to help shrink tumors (along with radiation).
  • To control cancer that has spread to organs or to relieve symptoms.

Side effects of chemotherapy vary depending on the type of drug and the dose used. They may include:

  • Hair loss.
  • Mouth sores.
  • Vomiting and nausea.
  • Loss of appetite.
  • Increased risk of infections.
  • Easy bruising or bleeding.
  • Fatigue.
  • Diarrhea.
  • Neuropathy—nerve damage that causes numbness, tingling and pain in hands and feet.
  • Hand-foot syndrome—redness on hands and feet that can lead to pain, sensitivity, blisters and sores.

Radiation therapy

This treatment destroys cancer cells with high-energy rays (such as x-rays). Treatment can range from a few days to a few weeks.

Most people with colorectal cancer who receive radiation get it from a machine that is outside the body. But radiation can also be delivered internally.

For colon cancer: It's not common to use radiation therapy to treat colon cancer, but it may be used after surgery if it appears the cancer has grown into nearby tissues.

For rectal cancer: Radiation therapy is often used along with surgery and chemotherapy. Radiation can make the tumor easier to remove or help keep cancer from coming back.

Radiation therapy can also be done to control cancer in people who aren't healthy enough to have surgery. And it can help ease symptoms—such as intestinal blockage, bleeding or pain—in people who have advanced cancer.

Radiation and chemotherapy (called chemoradiation or chemoradiotherapy) may be used to shrink a tumor before surgery.

Side effects of radiation may include:

  • Skin irritation where the rays hit the body.
  • Nausea.
  • Rectal irritation. This can cause diarrhea, bloody stools or painful bowel movements.
  • Bowel incontinence.
  • Bladder irritation. This can lead to problems like painful urination, blood in the urine or the feeling that you have to go to the bathroom often.
  • Fatigue.
  • Sexual problems, such as impotence (in men) and vaginal irritation (in women).

Other treatments

When cancer is advanced or chemotherapy isn't working, other treatments may be used:

Targeted therapy drugs affect cancer cells while sparing normal ones. They work by targeting specific gene and protein changes in cells that cause cancer. According to the ACS, targeted therapies are typically used with chemotherapy or on their own if chemotherapy isn't working.

Side effects of targeted therapy vary depending on the type of drug used. However, they are often less severe than the side effects of chemotherapy, according to the ACS. Still, some of the possible side effects of the drugs can be serious.

Immunotherapy drugs use the body's own immune system to fight cancer. They can be used in people whose colorectal cancer cells have tested positive for certain gene changes and are still growing after chemotherapy.

Side effects of immunotherapy may include fatigue, fever, cough, shortness of breath, itching, skin rash, nausea, loss of appetite, diarrhea, constipation and joint pain, according to the ACS.

Ablation and embolization destroy tumors in other areas of the body—usually the liver—where colorectal cancer has spread. They are often used when surgery is not an option and may help people with advanced cancer live longer. Ablation destroys a tumor in place by heating it with high-energy radio waves, freezing it or injecting concentrated alcohol into it. Embolization often uses small beads or particles to plug up the artery that delivers blood to the tumor.

Side effects of ablation may include abdominal pain, infection and internal bleeding. Side effects of embolization may include belly pain, fever, nausea, infection, blood clots and gallbladder inflammation. Liver function may also get worse.

Talk with your doctor

Your doctor can help you weigh your options for treating colorectal cancer. As you consider treatments, make sure to discuss potential side effects. Also, talk with your doctor about whether the goal is to get rid of the cancer, to control it or to ease symptoms and complications.

Reviewed 11/14/2022

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