"A nonsurgical treatment for lowrisk prostate cancer in which doctors inject a lightsensitive drug derived from deepsea bacteria into a patients bloodstream was shown in a trial to kill cancer cells without destroying healthy tissue.  Results of a trial in  patients showed that the drug which is activated with a laser to destroy tumor tissue in the prostate was so effective that half the patients went into remission compared with . percent in a control group.  These results are excellent news for men with early localized prostate cancer offering a treatment that can kill cancer without removing or destroying the prostate said Mark Emberton a University College London consultant urologist who led the trial. This is truly a huge leap forward.  The treatment called vasculartargeted photodynamic therapy or VTP was developed by scientists at the Weizmann Institute of Science in Israel in collaboration with the privatelyowned STEBA Biotech.  The lightsensitive drug used called WST is derived from bacteria found at the bottom of the ocean. To survive with very little sunlight they have evolved to convert light into energy with incredible efficiency Embertons team said in a study published in the journal Lancet Oncology.  The Weizmann scientists exploited this feature to develop WST a compound that releases free radicals to kill surrounding cells when activated by laser light.  Men with lowrisk prostate cancer are currently put under active surveillance where the disease is monitored and only treated when it becomes more severe. Radical therapy which involves surgically removing or irradiating the whole prostate has significant longterm side effects so is only used to treat highrisk cancers.  While radical therapy causes lifelong erectile problems and incontinence VTP only caused shortterm urinary and erectile problems which resolved within three months the researchers said. No significant sideeffects remained after two years.  In the trial only  percent of patients treated with VTP needed radical therapy compared with  percent of patients in the control arm who were under active surveillance.  The trial involved  treatment sites in  European countries most of which were performing VTP for the first time.  The fact that the treatment was performed so successfully by nonspecialist centers in various health systems is really remarkable Emberton said.  The VTP treatment is now being reviewed by the European Medicines Agency EMA for possible license but it likely to be several years before it can be offered to patients more widely.  Reporting by Kate Kelland editing by John Stonestreet Our StandardsThe Thomson Reuters Trust Principles. httpthomsonreuters.comenaboutustrustprinciples.html"