Treatment for advanced bowel cancer

When bowel cancer has spread outside the bowel to other parts of the body such as the liver, lung, or lining of the abdomen and pelvis (omentum and peritoneum), this is known as advanced or metastatic (stage 4) bowel cancer.

To control the cancer, slow its growth and manage symptoms such as pain, a combination of different treatments may be recommended. These may include drug therapies (chemotherapy, targeted therapy or immunotherapy), radiation therapy and surgery. For some people, the best option may be to join a clinical trial.

Read about treatment options for early bowel cancer.

Learn more about:

• Making treatment decisions
• Drug therapies
• Radiation therapy
• Surgery
• Thermal ablation
• Palliative treatment
• Video: What is palliative care?

Drug therapies

Advanced bowel cancer is commonly treated with drugs that reach cancer cells throughout the body. This is called systemic treatment, and includes chemotherapy, targeted therapy and immunotherapy.

The drugs used for bowel cancer are rapidly changing as clinical trials find newer drugs. Your medical oncologist will discuss which combination of drugs is best for your situation. You may also be able to get other drugs through a clinical trial.

Scans and blood tests will be used to monitor your response to systemic treatments. If results show that the cancer is shrinking or is under control, you’ll continue to have chemotherapy or targeted therapy or both. If the cancer is growing, that treatment will stop and your doctor will discuss other treatments.

Targeted therapy

This is a type of drug treatment that attacks specific features of cancer cells to stop the cancer growing and spreading. Monoclonal antibodies are the main type of targeted therapy drug used in Australia for advanced bowel cancer. They include:

Bevacizumab – This drug stops the cancer developing new blood vessels and growing. It is given as a drip into a vein (intravenous infusion) every 2–3 weeks, with chemotherapy.

Cetuximab and panitumumab – These drugs target specific features of cancer cells known as epidermal growth factor receptors (EGFR). They only work for people who have a normal RAS gene (known as RAS wild-type). The tumour will be tested for changes (mutations) in these genes before you are offered these drugs. These drugs are usually given as a drip into a vein (intravenous infusion). They may be given with chemotherapy or on their own after other chemotherapy drugs have stopped working.

Encorafenib – This drug is used to treat a type of colorectal cancer with a mutation in the BRAF gene. It is given as tablets you swallow daily and used in combination with cetuximab.

Side effects of targeted therapy

The side effects of targeted therapy vary depending on the drugs used. For a detailed list of side effects, visit eviq.org.au. Common side effects include:

• bevacizumab – high blood pressure, tiredness, bleeding and headaches
• cetuximab and panitumumab – skin problems (redness, swelling, an acne-like rash or dry, flaky skin), tiredness and diarrhoea
• encorafenib – fever, tiredness, joint pain, skin problems, sore eyes.

For more on this treatment, see Targeted therapy.

Immunotherapy

Immunotherapy uses the body’s own immune system to fight cancer. Checkpoint inhibitors are the main type of immunotherapy drug used for the small number of advanced bowel cancers that have a fault in the mismatch repair (MMR) gene. The drug pembrolizumab is given directly into a vein through a drip (infusion) and the treatment is repeated every 3 or 6 weeks. How many infusions you receive will depend on how you respond to the drug.

Side effects of immunotherapy

Like all treatments, checkpoint inhibitors can have side effects. Because these drugs act on the immune system, they can sometimes cause the immune system to attack healthy cells in any part of the body. This can lead to a variety of side effects such as:

• rash or itchy skin
• diarrhoea
• breathing problems
• inflammation of the liver
• hormone changes
• temporary arthritis.

Your doctor will discuss possible side effects with you. For more on this treatment, see Immunotherapy.

Radiation therapy

Radiation therapy can be used as a palliative treatment for both advanced colon and advanced rectal cancer. It can be used to control the growth of the tumour and relieve symptoms such as bleeding. If the cancer has spread to the bone or formed a mass in the pelvis, radiation therapy can reduce pain. For further details, see Radiation therapy.

If the tumour has spread to the liver, you may be offered a specialised type of radiation therapy. Options may include selective internal radiation therapy (SIRT, also called radioembolisation) or stereotactic body radiation therapy (SBRT).

Surgery

Some people are able to have surgery to remove bowel cancer that has spread. Generally, surgery is not recommended if you are unwell or the cancer has spread to many places in the body.

• If the cancer has spread to the liver or lungs, surgery may remove parts of the bowel along with all or part of other affected organs. This may be called an en-bloc resection.
• If the cancer has spread to the lining of the abdomen (peritoneum), some people have surgery to remove as many tumours as possible. This is known as a peritonectomy or cytoreductive surgery. Sometimes, a heated chemotherapy solution is put into the abdomen for 60–90 minutes during a peritonectomy. This is called hyperthermic intraperitoneal chemotherapy (HIPEC).

Thermal ablation

If the cancer cannot be removed with surgery, but has spread to only a small number of places in a single area, your doctor may recommend thermal ablation. This uses heat to destroy the tumour. The heat may come from radio waves (radio frequency ablation) or microwaves (microwave ablation). It is best performed in a specialised centre.

Palliative treatment

This is treatment that aims to slow the spread of cancer and relieve symptoms without trying to cure the disease. Treatments given palliatively for advanced bowel cancer may include surgery, chemotherapy, radiation therapy or targeted therapy.

For more on this, see Palliative care and Living with advanced cancer, and listen to our advanced cancer podcast.

Video: What is palliative care?

Watch this short video to see how palliative treatment aims to manage symptoms and improve quality of life without trying to cure the disease.