Advanced bowel cancer

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

Targeted therapy drugs work differently from chemotherapy drugs. While chemotherapy affects all rapidly dividing cells and kills cancerous cells (cytotoxic), targeted therapy drugs affect specific molecules within cells to block cell growth (cytostatic).

Two types of targeted therapy drugs are commonly used in Australia for advanced bowel cancer.

Bevacizumab – This drug blocks the growth of blood vessels that supply cancer cells. It is given as an injection into a vein (intravenously) every two weeks, with chemotherapy.

Epidermal growth factor receptor inhibitors (EGFR-Is) – These target special receptors on cancer cells. They only work for people who have a normal RAS gene. You will be tested for changes (mutations) in these genes before you are offered these drugs. EGFR-Is are usually given with chemotherapy but sometimes on their own after other chemotherapy drugs have stopped working.

If your medical oncologist thinks that a targeted therapy may help, they will discuss this with you. However, some targeted therapy drugs may be available only through a clinical trial.

Scans and blood tests will be used to monitor your response to systemic treatments. If results shows that the cancer is shrinking or is under control, chemotherapy and/or targeted therapy will continue. If the cancer is growing, you will stop the treatment and alternative treatments will be discussed.

Side effects of targeted therapy

The side effects of targeted therapy vary depending on the drugs used. Common side effects of bevacizumab include high blood pressure, tiredness, bleeding, low white blood cell counts, headaches, mouth sores, loss of appetite and diarrhoea. The most common side effects of EGFR-Is include acne-like rash, headache, tiredness, fever and diarrhoea.

Radiation therapy can also be used as a palliative treatment for both colon and rectal cancer. It can be used to stop bleeding and if the cancer has spread to the bone or formed a mass in the pelvis, it can reduce pain. 

If the cancer has spread to other parts of the body, you may still be offered surgery. This can help remove small secondary cancers (e.g. in the liver or lungs) or clear up a bowel obstruction.

You may have surgery to remove parts of the bowel along with all or part of other organs. This is called an en-bloc resection.

The type of operation used for advanced bowel cancer will depend on your situation, so talk to your surgeon about what to expect.

Your medical team will advise what kind of follow-up and treatment is recommended after surgery. Regular check-ups have been found to improve survival for people after surgery for bowel cancer, so you should have check-ups for several years.

If the cancer is advanced when it is first diagnosed or returns after treatment, your doctor will discuss palliative treatment for symptoms caused by the cancer, such as pain.

Palliative treatment aims to manage symptoms without trying to cure the disease. It can be used at any stage of advanced bowel cancer to improve quality of life. It is not just for people who are about to die and does not mean giving up hope. Rather, it is about living for as long as possible in the most satisfying way you can.

As well as slowing the spread of cancer, palliative treatment can relieve pain and help manage other symptoms. Treatment may include surgery, radiation therapy, chemotherapy, targeted therapy or other medicines.

Palliative treatment is one aspect of palliative care, in which a team of health professionals aim to meet your physical, emotional, practical and spiritual needs. For more information, visit your local Cancer Council website or call 13 11 20 for free copies of Understanding Palliative Care and Living with Advanced Cancer, or download digital copies from this page.

Find out how palliative treatment aims to manage symptoms and improve people’s quality of life without trying to cure the disease.