Treatment options for colorectal cancer

How colon and rectal cancer are treated: surgery, ostomies, chemotherapy, radiation, targeted therapy and immunotherapy, and how your team tailors a plan to you.

6 min read · last reviewed September 30, 2026

There are many ways to treat colorectal cancer, and they keep getting better. Your plan will be built around you: where the cancer is, its stage, what tests on the cancer show, your general health, and what matters most to you.

Most cancer centres have a team that meets to plan care together. It may include a surgeon, a medical oncologist (chemotherapy doctor), a radiation oncologist, nurses and others. Your team will tailor your treatment, so yours may look different from someone else's. This guide gives you a map of the main options.

Surgery

For most colon cancers that haven't spread, surgery is the main treatment. The goal is to remove the cancer and lower the chance it comes back.

• Very early cancers in a polyp can sometimes be removed during a colonoscopy.
• Colectomy means removing the part of the colon with the cancer, plus nearby lymph nodes. The two healthy ends are then joined back together.
• Rectal surgery removes part or all of the rectum. Where the cancer sits decides which operation is best.

Many operations are done through small cuts, called keyhole (laparoscopic) or robotic surgery. This can mean less pain and a shorter hospital stay.

Will I need an ostomy?

An ostomy is an opening on the belly, called a stoma, where stool leaves the body into a pouch. A colostomy comes from the colon, and an ileostomy from the small bowel.

• Many people don't need one.
• Some people need one for a few months while the join in the bowel heals. It is then closed with a smaller operation.
• Some people, most often with cancer very low in the rectum, need a permanent one.

Most people with an ostomy go back to work, exercise, travel and intimacy. An ostomy nurse will teach you how to care for it.

Something you can do: Ask to meet an ostomy nurse before surgery. They can help choose the best spot for a stoma, just in case.

Chemotherapy

Chemotherapy uses drugs to kill cancer cells or stop them growing. It may be given through a vein, as pills, or both.

• After surgery (adjuvant chemo): Often suggested for stage III colon cancer, and sometimes stage II, to lower the chance of the cancer coming back. It usually lasts about 3 to 6 months.
• Before surgery: Often used for rectal cancer, and sometimes for colon cancer, to shrink the tumour first.
• For cancer that has spread: To shrink the cancer, control it and help you feel better.

Common combinations have short names. FOLFOX uses fluorouracil (5-FU), leucovorin and oxaliplatin through a vein. CAPOX (also called XELOX or CAPEOX) uses capecitabine pills with oxaliplatin. FOLFIRI uses irinotecan instead of oxaliplatin.

Side effects depend on the drugs. They can include tiredness, diarrhea, nausea, mouth sores, and a higher chance of infection. Oxaliplatin can cause tingling in the hands and feet, and sensitivity to cold. Capecitabine can make the hands and feet red and sore. Tell your team early about side effects. Most can be eased.

Something you can do: Keep a thermometer at home. If your temperature is 38 °C (100.4 °F) or higher during chemotherapy, call your cancer centre's 24-hour line right away.

Radiation therapy

Radiation uses high-energy beams to destroy cancer cells in one area. It is used much more for rectal cancer than colon cancer.

• Chemoradiation: Radiation given over about 5 to 6 weeks, with a chemotherapy pill or infusion to make the radiation work better.
• Short-course radiation: Radiation over about 5 days.

Radiation is often given before surgery to shrink the tumour. It can cause tiredness, skin soreness, loose stools and bladder irritation. These usually settle after treatment ends.

Newer approaches for rectal cancer

Total neoadjuvant therapy (TNT). This means giving all the chemotherapy and radiation before surgery, instead of splitting them before and after. It is now a common approach for many rectal cancers.

Watch and wait. In some people, the cancer disappears completely after chemotherapy and radiation. Some cancer centres may then offer very close checkups, with scopes and scans, instead of surgery right away. This is not right for everyone, and it needs regular follow-up. Surgery is still possible if the cancer comes back. Ask if this could be an option for you.

Immunotherapy

Immunotherapy helps your own immune system find and attack cancer. The main type, called checkpoint inhibitors, works best in cancers that are dMMR or MSI-high. This is why MMR or MSI testing is so important.

• For dMMR or MSI-high cancer that has spread, immunotherapy is often a first choice.
• For dMMR or MSI-high rectal cancer, newer research shows immunotherapy alone may make the cancer disappear in many people, so some may avoid radiation and surgery. This is a fast-changing area. Ask your team whether it applies to you.

Immunotherapy side effects are different from chemo. The immune system can sometimes attack healthy parts of the body. Report new diarrhea, cough, shortness of breath, rash or yellow skin right away.

Targeted therapy

Targeted drugs attack specific features of cancer cells. They are mostly used for colorectal cancer that has spread, often with chemotherapy. Which one depends on tests like KRAS, NRAS, BRAF and HER2. Some block the blood supply a tumour needs to grow. Others block signals that tell cancer cells to grow.

If the cancer has spread

When colorectal cancer has spread to the liver or lungs, treatment may still aim to remove it. If there are only a few spots, surgery or treatments that destroy tumours with heat (ablation) may be possible. Otherwise, chemotherapy, targeted therapy or immunotherapy can control the cancer, often for a long time.

Supportive and palliative care

Supportive care, also called palliative care, helps with pain, nausea, tiredness, eating and emotions. It's for anyone with cancer, at any stage, alongside other treatment. It is not only for the end of life.

Clinical trials

Clinical trials test new treatments or better ways to use current ones. They may give you access to new options. Ask whether there is a trial that fits you.

Questions to ask your care team

• What is the goal of my treatment?
• What treatments do you suggest for me, and in what order?
• Will I need an ostomy? Would it be temporary or permanent?
• What side effects should I expect, and which ones should I call about?
• Could immunotherapy, watch and wait, or a clinical trial be options for me?
• Who do I call, day or night, if I have a problem?

This article is general information, not medical advice. Talk with your health care team about your own situation. In an emergency, call 9-1-1 or your local emergency number.

In an emergency, call 9-1-1 or your local emergency number.

General information, not medical advice. It does not replace your own care team. If you think you or someone else is having a medical emergency, call 9-1-1 or your local emergency number. If you are in crisis or thinking about suicide, call or text 9-8-8 (Canada and the US).

Back to Colorectal cancer