A common cold virus has been harnessed for use as a cancer killer.
Scientists modified the adenovirus so that it could invade and destroy tumours without damaging healthy cells.
The virus was allowed to keep enough of its genetic "signature" to trigger an immune response which safely eradicated it after the job was done.
Adenoviruses have been used before to tackle cancer. But in those experiments scientists were forced to weaken the virus to prevent it causing organ damage.
The new research showed it was possible to "tweak" the virus so that it launched a full-strength attack on cancer while not hurting its host.
The work, reported in the journal PLoS Pathogens, was conducted in mice, whose livers were left undamaged by the virus.
Lead author Professor Leonard Seymour, from Oxford University, said: "The approach we developed is easy to use and flexible. It may help in the development of future therapeutic viruses that are specific to certain disease sites. This modified virus was effective in these laboratory studies, but transfer of the technology to the clinic to be used with patients will require further work - and it will probably be at least two years before this can happen."
Dr Lesley Walker, from Cancer Research UK, which funded the study, said: "Decades of research has already led to the development of new and exciting approaches to treating cancer in a more targeted and efficient way.
"The ability to produce viruses that can replicate in cells, but have any harmful characteristics removed so they are no longer lethal, should provide a new platform for development of improved cancer treatments - as well as better vaccines for a broad range of viral diseases."