Prostate Cancer Focal Therapy Shows Promise

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This MRI thermometry image shows the temperature of a prostate tumor as it is being ablated.
This MRI thermometry image shows the temperature of a prostate tumor as it is being ablated.

NEW ORLEANS—Focal prostate laser ablation of prostate cancer (PCa) may be safely performed in patients undergoing active surveillance for non-aggressive tumors, according to new data presented at the Society of Interventional Radiology's 38th Annual Scientific Meeting.

The treatment is guided with magnetic resonance imaging (MRI) or real-time ultrasound fused to pre-procedural multi-parametric MRI.

“This emerging technique may become an option for certain patients with low Gleason score cancer, given the early suggestion of limited side effects,” said Hayet Amalou, MD, a research fellow at the Center for Interventional Oncology at the National Institutes of Health, Bethesda, Md.  “With future simplifications in technology, perhaps focal ablative therapy will become a sort of male lumpectomy for certain tumors. Also, using ultrasound fusion to guide the laser ablation allows the procedure to be performed without occupying an MRI.”

Focal therapies could allow for cancer monitoring and control without the morbidity associated with whole gland therapies, Dr. Amalou said. They also might make it possible for patients to receive repeat treatments less invasively, she said.

Dr. Amalou described an ongoing multidisciplinary clinical trial in which 14 patients underwent focal laser ablation for Gleason 6 and Gleason 7 (3+4) biopsy-proven PCa. The tumors were photogenic on MRI.

“MRI provides the definition of tumor extent and allows dynamic control of energy deposition using real time MR thermometry,” Dr. Amalou told Renal & Urology News. “Laser ablation was chosen because its energy delivery system may ablate the tumor with a sharper edge or margin (transition zone) compared to cryoablation or high-intensity focused ultrasound.”

The ablations may be performed safely near the capsule, urethra, nerves and rectum, with appropriate precautions, such as the use of MRI thermometry along with protective hydro-dissection of the space between the rectum and prostate, Dr. Amalou explained. Patients receive antibiotic prophylaxis, and bladder catheterization for one day post-ablation. The treatment was well tolerated. It is postulated that  major complications that commonly occur with whole gland therapies, including erectile dysfunction and urinary incontinence, will be less common with focal therapies.

Dr. Amalou said this technique requires tight communication and collaboration between urologists, diagnostic radiologists, and interventional radiologists. At the NIH, this multidisciplinary team includes Peter Pinto, MD, who is the principle investigator of the clinical trial, Peter Choyke, MD, Baris Turkbey, MD, Anthony Hoang, MD, and Bradford Wood, MD.

“Although speculative, the complications and risks of whole gland treatment may be deferred, or potentially avoided entirely, without missing the window of opportunity for early intervention,” Dr. Amalou said.  “However, results are short-term thus far, and low-grade prostate cancer can be slow growing.  Given our limited ability to predict cancer outcomes based solely upon pathology, morphology or Gleason score, the community should aggressively seek improved predictability based on combining imaging modalities, pathology and other independent risk factors.”   

Although the preliminary findings are promising, they are still short-term, she said. Low Gleason score tumors are known to be very slow growing, so much longer-term follow-up is warranted before the technique is widely accepted.

                                                     

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