Abstract
There has been interest in using viruses to treat cancer for over a century. Recent clinical efforts, driven on by significant preclinical advances, have focussed on the safety of using replication-competent viruses. Recently published clinical trials of six oncolytic viruses (adenovirus, reovirus, measles, herpes simplex, Newcastle disease virus and vaccinia) have added to the accumulating data that endorse oncolytic viruses as a safe and well tolerated treatment approach. Conclusive evidence of efficacy remains to be demonstrated, but randomised clinical trials are now underway.