Advanced bowel cancer treatment

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.

There are a range of different targeted therapy drugs. These drugs will only work for bowel cancers with particular gene changes (mutations). Your medical oncologist will usually do tests on the biopsy sample (or may do blood tests) to see which targeted therapy is likely to work for you.

Some targeted therapy drugs are given as tablets, while others are given as a drip into a vein in hospital. They may sometimes be given at the same time as chemotherapy, or given after you have stopped chemotherapy treatment.

Side effects

The side effects of targeted therapy vary depending on which ones are used. For a detailed list of side effects, visit the NSW Government's eviQ and search for the drug you are being given. Some of the more common side effects may include:

• tiredness
• skin problems
• diarrhoea
• joint pain
• skin problems
• sore eyes.

Immunotherapy

Immunotherapy is a type of drug therapy treatment that 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

Checkpoint inhibitor immunotherapy acts on the immune system, so it 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. 

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).

Learn more about secondary liver cancer.

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, surgery may remove parts of the bowel along with all or part of other affected organs. This is called an en-bloc resection and is usually for locally advanced bowel cancer. If the liver, lungs or other organs are affected, a separate surgery (called metasectomy) may remove some or all of the cancer in that organ.
• If the cancer has spread to the lining of the abdomen (peritoneum), some people have surgery to try to remove all of the cancer – however, this can only be done when there is limited cancer and spread. 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 has spread to only a small number of places in a single area, such as the liver or lungs, your doctor may recommend thermal ablation. This may use 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. Cryoablation is a similar process that may sometimes be offered, and uses cold or freezing instead of heat.

Palliative treatment

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

Learn more at Palliative care and Living with advanced cancer, and listen to Cancer Council's advanced cancer podcast.