Scientists hope to use the body's immune system to fight tumours

Animal tests suggest that a treatment given to just one tumour produces an immune response that targets secondary growths in other places.

Researchers from Chicago University now hope the same effect can be reproduced in humans with cancer.

If so, it could offer a way to tackle cases where more advanced cancers have a foothold in many parts of the body.

At the moment, once a cancer has spread beyond its initial site, it becomes far harder to treat in many cases - and the chances of overall survival begin to fall.

One way that researchers are trying to improve these odds is by boosting the body's own immune system so that it can mount a body-wide assault on cancer cells.

Hidden enemy

Unlike foreign invaders such as bacteria, cancers can often evade immune defences and go unrecognised as a threat.

Some tumours appear capable of throwing up a "barrier" around their fringes which stops immune cells getting hold of fragments of the tumour which can be used to coordinate an attack on the abnormal cells.

In addition, other types of cancer can interfere with the activation of "killer T cells" - immune cells which arrive to destroy tumour cells.

The Chicago team overcame this problem by activating the production of a body chemical called LIGHT within a tumour.

This protein then produced a two-pronged attack on the cancer.

Not only did it increase production of a chemical which attracts "killer T cells" to the tumour site, it also switched these cells into an active state once they arrived.

This had a marked effect on the size of the treated tumour, and also seemed to encourage tumour regression in other parts of the body.

However, while this worked well in different types of mice, it is by no means certain that it would happen in humans.

In the journal Nature Immunology, the researchers wrote: "Here we have shown that the expression of LIGHT in the tumour microenvironment acts as a potent immunotherapy for cancer by targeting the tumour barrier."