Figure 1 – Ideal Scenario for Focal Therapy of Prostate Cancer:
Identification of the tumor focus as preparation for focal therapy is crucial. Data have shown that the correlation of clinically significant prostate cancer between fusion biopsy and whole mount section is present in only 75% of cases. 1 Additionally, there is data showing that mpMRI underestimates the true tumor size, with pathologic tumor size being 2.7 times larger than the tumor identified on mpMRI. 2 It is important to remember that when treating with focal therapy, a safety margin of 15 mm around the region of interest in the mpMRI is required.
Those who object to the option of focal therapy state that multifocal tumors are present in over 60% of prostate cancer cases and bilateral tumors are present in 82% of cases, precluding focal therapy from being a good therapeutic strategy. Moreover, when assessing the secondary tumors of prostates where the primary tumor was treated with focal therapy, clinically significant cancer (Gleason score >=7) is present in a staggering 36.4% of cases with a tumor volume >=0.5 ml in 17.8% of cases. 3
The efficacy of focal therapy was discussed next. In a systematic review published in 2014, it was stated that the perioperative, functional, and disease control outcomes of focal therapy are encouraging within a short-to-medium-term follow-up. 4 Studies have shown a large variety of positive biopsy cores following treatment with 0-64% of patients demonstrating positive biopsy cores following treatment. 5 When comparing focal therapy to active surveillance, a randomized trial has shown that focal therapy is superior, 6 with a Hazard ratio of 0.35 (95% CI 0.25-0.48) with positive control biopsy rate within 24 months of 50%.
Lastly, Dr. Ganzer assessed the outcome of salvage treatment after failed focal therapy. In 2017 a study was published assessing the outcome of 22 patients after failed focal therapy who underwent salvage robotic prostatectomy and compared to 44 patients who underwent primary robotic radical prostatectomy. 7 The results demonstrated that the complication rate was comparable, as well as the continence rates at 1 and 2 years following therapy. However, the potency rates were significantly worse after salvage radical prostatectomy, and the biochemical recurrence-free survival rate was 56.3% vs. 92.4% (p=0.001), in favor of the 44 patients treated with primary robotic radical prostatectomy.
Dr. Ganzer concluded his talk with some focal therapy studies expected to have results in the next year. A study evaluating MRI/US fusion imaging and biopsy in combinations with nanoparticles directed focal therapy for ablation of prostate tissue (NCT 02680535) should have results in the next year. This is a multicenter trial including 45 patients with results expected in December 2019. Another expected trial is the PART trial comparing the efficacy of focal therapy to standard treatment options, led by Dr. Freddy Hamdy. Lastly, we also expect the results of a prospective trial assessing the results of robotic surgery after foal therapy, led by Dr. Paul Cathcart, in Queen Mary University, London.
Presented by: Professor Roman Ganzer, FEBU, Head Physician, Specialist in Urology / Robot-Assisted Surgery and 3D Laparoscopy in the Urogenital Field, Focal Therapy of Prostate Carcinoma, Bad Tölz, Germany
Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre @GoldbergHanan at the 34th European Association of Urology (EAU 2019) #EAU19 conference in Barcelona, Spain, March 15-19, 2019.
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2. Priester A. et al. PNFBA-10 Focal Therapy of Prostate Cancer: Defining Appropriate Treatment Margins Using MRI: Whole Mount Co-Registration. J. Urol 2017. https://www.auajournals.org/article/S0022-5347(17)34705-5/fulltext
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7. Nunes-Silva et al. Effect of Prior Focal Therapy on Perioperative, Oncologic and Functional Outcomes of Salvage Robotic Assisted Radical Prostatectomy. J Urol. 2017 Nov;198(5):1069-1076. doi: 10.1016/j.juro.2017.05.071. Epub 2017 May 25.