British surgeons use pen-like probe to spot brain tumours for the first time . Laser helps medics tell difference between healthy and cancerous tissue . Pioneering technique could shave three-hour off 30 minutes operations .
British surgeons use pen-like probe to spot brain tumours for the first time . Laser helps medics tell difference between healthy and cancerous tissue . Pioneering technique could shave 30 minutes off three-hour operations .