Doctors in London, UK, have successfully treated cancer patients with a genetically engineered herpes virus.

A trial of 17 patients with head and neck cancer found that the virus helped kill tumours in most patients when used alongside with chemotherapy and radiotherapy.

The treatment involves genetically manipulating the herpes virus to grow inside tumour cells.

The virus then multiplies to kill tumour cells from inside, and produces a human protein to activate the immune system.

Of the 17 patients tested, two relapsed. However, 82% showed no signs of cancer more than two years later.

Further trials are now planned for later this year.