A clinical trial at Washington University School of Medicine and the Siteman Cancer Center is evaluating vascular-targeted photodynamic therapy in men with localized prostate cancer. This innovative, “microinvasive” procedure uses a lightsensitive drug designed to selectively destroy tumors illuminated by lasers.
This approach has the potential to eradicate tumors with minimal side effects such as incontinence and impotence that have been associated with surgery and radiation therapy.
“We know that many prostate cancers are over treated,” says Gerald Andriole Jr., MD, chief of the Division of Urologic Surgery and one of study’s principal investigators. “This procedure is intended to selectively target the tumor-bearing portion of the prostate, which should reduce the unwanted side effects associated with more aggressive treatments.”
Photodynamic therapy is just one type of ablation therapy being evaluated by Washington University urologists for localized prostate cancer. They also offer focal cryotherapy, which involves freezing the prostate. In this approach, the physicians use biopsy information from a novel 3-dimensional, ultrasound-guided to target the diseased portion of the prostate.
The Phase II trial for photodynamic therapy enrolled men diagnosed with localized prostate cancer who have chosen active surveillance, also known as “watchful waiting.” Laser fibers are inserted into the prostate under ultrasound guidance. The exact location of fiber placement is calculated using both MRI imaging and information gained from the prostate biopsy. Patients then receive an IV infusion of the photosensitizing drug WST11, which targets blood vessels that feed cancer growth.
After the drug reaches the prostate, the laser fibers are activated to deliver light to the tumor. When that light comes into contact with the drug, laser fibers destroy the blood vessels around the tumor, choking off its blood supply.
The outpatient procedure is performed under general anesthesia and takes about one hour. Patients can generally resume their normal activities within a day. They will be monitored after treatment with regular PSA tests and a needle biopsy performed at six months.