The following article is part of conference coverage from the 2018 American Urological Association meeting in San Francisco. Renal and Urology News’ staff will be reporting live on medical studies conducted by urologists and other specialists who are tops in their field in kidney stones, prostate cancer, kidney cancer, bladder cancer, enlarged prostate, and more. Check back for the latest news from AUA 2018.
SAN FRANCISCO—Partial gland ablation for low-risk prostate cancer (PCa) using laser energy and a photosensitive drug results in a significantly decreased risk of disease progression compared with active surveillance (AS), according to 4-year outcome data from the first and only prospective randomized controlled trial evaluating focal therapy for PCa.
Trial results, presented at the American Urological Association 2018 annual meeting by Inderbir Singh Gill, MD, Chair and Distinguished Professor of Urology at the University of Southern California Keck School of Medicine in Los Angeles, found that men who underwent the laser procedure—vascular-targeted photodynamic therapy (VTP)—were less likely to require radical treatment than men on AS.
“Partial gland ablation with VTP decreases progression of low-risk cancer to grade group 2 or higher, and therefore reduces conversion to radical therapy minimizing the comorbidity associated with radical therapy, Dr Gill told Renal & Urology News. “And that is clinically meaningful for a large majority of men.”
VTP was recently approved in Europe for PCa focal therapy in men with low-risk disease based on 2-year data, which were published in Lancet Oncology (2017;18:181), but it remains investigational in the United States. The procedure involves intravenous administration of padeliporfin, which circulates throughout the body. When exposed to light, the drug releases free hydroxyl and superoxide radicals, causing occlusion of the microvasculature, resulting in ischemic coagulative necrosis, explained Dr Gill, Executive Director of the USC Institute of Urology. Laser fibers are introduced to the prostate via the transperineal route and placed at the site requiring ablation. Laser light is administered for 22 minutes.
For the study, Dr Gill and his collaborators randomly assigned 413 men with low-risk PCa to undergo VTP or to be placed on AS. VTP recipients had significantly lower rates of crossover to radical therapy at 3 years (7% vs 33%) and 4 years (24% vs 53%). Compared with the AS patients, the VTP recipients had a reduction in absolute risk of 30% and 29% at 3 and 4 years, respectively. Both cohorts has similar 4-year rates of metastasis-free, cancer-specific, and overall survival.
Following VTP, negative biopsy rates were similar for the apex, mid-gland, and base, indicating the ability of VTP to ablate various spatial locations throughout the prostate, Dr Gill’s team reported.
Within 5 to 10 years of starting AS, Dr Gill noted, approximately 30% to 60% of men will convert to radical therapy, which is associated with high rates of erectile dysfunction and urinary incontinence. “If we can keep these men from converting to radical therapy… it will improve their quality of life down the road substantially.”
Gill I, Emberton M, Azzouzi A, et al. Four-year follow-up of a phase 3 prospective randomized trial of vascular-targeted phototherapy versus active surveillance for low-risk prostate cancer. Oral presentation at the American Urological Association 2018 annual meeting in San Francisco, May 18–21. Abstract LBA23.