And science is finding a way to harness it.

This just published in The New England Journal of Medicine: a fascinating story of a 52 year old man with stage 4 (advanced) melanoma that was successfully cured of the disease, using his own blood.

Researchers in the US who were treating the patient extracted white blood cells, the key component of the immune system, and grew one type – the infection-fighting CD4+ T cells – in the laboratory. The cloned T cells, which had been vastly expanded, were then reinfused to the patient to fight the cancer.

The man was diagnosed with stage four melanoma, when death normally occurs within months. The cancer, triggered by sunburn, started in a mole on the skin and had spread to a lymph node in his groin and to his lungs. But, two months after the T-cell treatment, scans revealed no tumor. Two years later, when he was last checked, the man remained free of the disease. He had previously had surgery and drug treatment without any response.

A promising new therapy? We'll have to exercise patience, immunotherapy is proving to distinguish other cancers, such as kidney cancer, but scientists will need to conduct more, larger studies due to it's being "complex and difficult to use."

Check it out;

How immunotherapy works

* 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 tumors 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 tumor cells.

Take care to stay cancer free so you can live a long and prosperous life - in great health.