* Cancer immunotherapy is the technique of harnessing the body's immune system to attack the cancer.

* The immune system normally responds to threats to the body by distinguishing between itself and foreign invaders.

* In the case of cancer, this is difficult because most tumours consist of the body's own cells growing out of control.

* However, many cancer cells display unusual antigens or receptors on their surface that allows them to be identified.

* Antibodies and cancer vaccines to stimulate the immune system are being developed to attack these tumour cells.