ABOUT BOWEL CANCER
Chemotherapy, targeted therapy and immunotherapy
Chemotherapy, targeted therapy and immunotherapy are often recommended as part of a treatment plan for bowel cancer. They may have side effects but, if recommended, this usually means the benefits are likely to outweigh the adverse effects.
Chemotherapy therapies for bowel cancer
Chemotherapy
Chemotherapy treatment involves the administration of drugs that either kill cancer cells or prevent them from dividing. When given by mouth, or by injection or infusion into a muscle or the bloodstream, it is termed systemic chemotherapy.
When placed directly into the cerebrospinal fluid, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas. This is known as regional chemotherapy.
There are a number of medicines used in New Zealand for the treatment of bowel cancer. Several chemotherapy drugs – used for both early-stage and metastatic bowel cancer – are publicly funded in New Zealand by the government funding agency PHARMAC. These are available to eligible patients at no charge.
These funded medicines are often used in combination with immunotherapy drugs in the treatment of metastatic bowel cancer.
Targeted and immune therapy for advanced bowel cancer
Targeted therapies and immune therapies are newer additions to the range of treatments available for bowel cancer.
Targeted therapies became more widely available in the early 2000s, while immune therapies are more recent and have been used since around 2017. Both are part of a rapidly growing area of cancer treatment, with specific indications and uses in the treatment of bowel cancer.
In Aotearoa New Zealand, these treatments are currently used for advanced (metastatic) bowel cancer.
Targeted therapies
Targeted therapies are drugs designed to target specific biomarkers – characteristics of how a cancer cell is formed. These treatments aim to attack cancer cells while causing less harm to healthy cells compared with traditional chemotherapy.
Examples include:
- cetuximab (Erbitux)
- bevacizumab (Avastin)
Immune therapies
Immunotherapy treatments help the body's own immune system recognise and destroy cancer cells.
These drugs can be particularly effective for people whose bowel cancer has a mismatch repair deficiency, such as those with Lynch syndrome.
An example is:
- pembrolizumab (Keytruda)
What is the difference between these and chemotherapy?
Traditional chemotherapy uses drugs that are toxic to cells – particularly those that divide rapidly, such as cancer cells. Because chemotherapy affects rapidly dividing cells, it can also impact healthy cells, which can lead to side effects.
Chemotherapy is a broad treatment approach and can be effective for many types of cancer. It is often used as a first-line treatment – meaning it may be one of the first treatments offered after a bowel cancer diagnosis.
Targeted therapy and immunotherapy are more personalised approaches. Their effectiveness depends on the specific biomarkers present in the tumour, or whether there are particular genetic changes such as mismatch repair deficiency.
These features can be identified through:
- biopsy samples
- testing performed after a tumour is surgically removed
While targeted therapies and immunotherapies can be used on their own to help control disease, shrink tumours, and manage symptoms, they are often used alongside chemotherapy to improve overall treatment effectiveness.
Decisions about which treatments are used are made by an oncologist, in discussion with the patient, so that care can be tailored to the individual and their specific type of bowel cancer.
Funded treatments currently available in Aotearoa New Zealand
A number of medicines are used in New Zealand for the treatment of bowel cancer. Several chemotherapy drugs – used for both early-stage and metastatic bowel cancer – are publicly funded by the government funding agency PHARMAC. These medicines are available to eligible patients at no cost.
Funded chemotherapy medicines used in New Zealand include:
- 5-FU (5-fluorouracil)
- capecitabine (Xeloda)
- irinotecan (Camptosar)
- oxaliplatin (Eloxatin)
Treatment commonly involves a combination of two or more drugs, for example:
- FOLFOX – 5-FU + leucovorin* + oxaliplatin
- FOLFIRI – 5-FU + leucovorin + irinotecan
- FOLFOXIRI – 5-FU + leucovorin + oxaliplatin + irinotecan
- CAPOX or XELOX – capecitabine + oxaliplatin
* Leucovorin is a reduced folic acid. Leucovorin is used in combination with other chemotherapy drugs to either enhance effectiveness, or as a “chemoprotectant”.
Targeted and immune therapy drugs currently available in Aotearoa New Zealand
