Focal Therapy for Prostate Cancer Advances
MRI can pinpoint a prostate tumor for targeted treatment.
MILAN—Laser ablation, cryotherapy, and hemiablative brachytherapy are among the novel approaches that show promise for the focal treatment of localized prostate cancer (PCa), according to studies presented at the 28th annual congress of the European Association of Urology. Most of these treatments are performed under magnetic resonance imaging (MRI) guidance.
Uri Linder, MD, and collaborators at the University Health Network in Toronto reported on the first comprehensive safety study and initial biological response to MRI-guided and controlled laser focal ablation in men with localized PCa. The phase 1 study included 38 men with low-to-intermediate risk localized tumors. All patients underwent the procedure on an outpatient basis. Under MRI guidance, surgeons placed laser fibers within the prostate near the tumor via the perineum. The median follow-up was 538 days. No intra-procedure complications occurred.
Of 34 patients who had post-procedure biopsy, 16 (47%) had negative findings, and nine (26%) had a negative biopsy in the ablated quadrant of the prostate, but had cancer detected in the contralateral lobe. Of 10 patients with Gleason 3+4 disease, eight had negative findings.
The average baseline PSA level was 5.6 ng/mL; at four months, the average PSA level was 3.6 ng/mL. No patient had a urinary tract infection or post-procedure fever. Of 32 patients with mild or no erectile dysfunction prior to the procedure, 31 (96%) maintained potency after the procedure without the use of phosphodiesterase-5 inhibitors.
The researchers concluded that the initial biologic response to treatment suggests that tumors can be completely ablated in 75% of cases without incurring significant morbidity, the procedure might be a viable option for patients with Gleason 3+4 disease. They noted that the pre- and post-procedure work-up imaging and biopsy schemes need to be evaluated further for better patient selection and significant tumor detection. In addition, the treatment technique needs to be refined to achieve higher rates of complete ablations.
In a separate study, Kazutaka Saito, MD, and colleagues at Tokyo Medical and Dental University Graduate used hemiablative brachytherapy using I-125 seeds to treat 16 men with unilateral prostate tumors as demonstrated with extended prostate biopsy. All had clinical stage T2a or less, Gleason score of 7 or less, a maximum cancer length less than 10 mm, and a PSA value less than 20 ng/mL. The target lobe was treated up to the midline as defined by the urethra. I-125 seed implantation was used to deliver a dose of 160 Gy under real-time ultrasonographic guidance. The men had a median age of 72 years, and 57% had low-risk and 43% had intermediate-risk PCa.
The median follow-up was nine months. No post-treatment severe acute complications such as urinary retention or bleeding were observed. Among sexually active patients, ejaculatory function was preserved without dry ejaculation during follow-up. PSA values decreased significantly without biochemical failure based on the Phoenix definition (nadir plus 2 ng/mL). MRI revealed no evidence of residual or new lesions at 12 months. All patients are alive except one who died from an unrelated cause 15 months after treatment.
“Based on the initial results, hemiablative brachytherapy can be a treatment option in focal therapy for unilateral prostate cancer in patients selected using extended biopsy and MRI,” the authors concluded in their study abstract.
In a third presentation, researchers from The Netherlands reported findings of a study including 10 men with histologically confirmed local recurrence of PCa following radiotherapy. Jurgen J. Fütterer, MD, PhD, of Radboud University Nijmegen Medical Centre in Nijmegen, and colleagues noted that cryosurgery for PCa under transrectal ultrasound guidance has been performed for several years for salvage treatment purposes after radical prostatectomy or radiotherapy. Due to poor visibility, however, high complication rates are not uncommon. MRI-guided cryosurgery may reduce these high complication rates because it has excellent soft tissue contrast. Additionally, they, pointed out, MRI guidance enables both accurate lesion targeting as well as three-dimensional monitoring of iceball growth.
For the procedure, surgeons inserted a urethral-warmer into the urethra and placed a transperineal plate attached to a flexible arm against the perineum. They inserted cryoneedles with real-time MRI guidance and inserted a rectal warmer into the rectum. Both warmers were flushed with warm water to protect the tissue from freezing. Iceball formation and tissue coverage was monitored continuously under near real-time MRI guidance. Two freeze-and-thaw cycles were performed. Treatment time was defined as from the moment the first MR image was performed until the last MR image was finished. Follow-up consisted of PSA-level measurement every 3 months and a multi-parametric MRI after 3, 6 and 12 months.
The procedure was technically feasible in all patients, the investigators reported. In one patient the urethral-warmer could not be inserted. This procedure was cancelled and successfully repeated two months later. Median age of the patients at the time of treatment was 67 years (range 52-76 years), their median PSA level was 3.7 ng/mL (range 0.9-8.7) and Gleason scores varied from 7-10. The median treatment time was 133 minutes (range 91-242 minutes). The median hospitalization time was two days (range 2-3 days). Two patients experienced mild urine retention and one had hematospermia.
Three months follow-up is known for the first six patients. Their PSA level decreased to a median of 1.3and multi-parametric MRI showed no presence of recurrent tumor. After six months, one of three assessed patients had a histopathologically proven local recurrence just above the area previously treated. He was retreated with MRI-guided cryoablation. Follow-up is not known yet.