The objective of focal ablative therapy of prostate cancer is to achieve oncological disease control while preserving quality of life. There are many energy sources available to focally ablate prostate cancer. Cryotherapy is the most versatile energy source since the energy can be delivered anywhere in the prostate gland. Unlike HIFU, calcifications do not interfere with delivery of the energy. The advantage of cryotherapy over electroporation is that cryo-energy delivery is monitored in real time with temperature probes and by visualizing the advancing ice-ball.
Beginning in 2017, our institution has enrolled over 700 men with focal prostate cancer associated with an MRI target into a clinical trial (clinicaltrial.gov identifier number: NCT07184957 and IRB #17-00354). All men enrolled in this study undergo a pre-treatment MRI and MRI guided biopsy coupled with a 12-core random systematic biopsy. The ablation planning is designed to eradicate the MRI target with a 10 mm margin when clinically feasible. In some cases, the treatment planning is a hemi-ablation. For medial cancers, the ablation planning typically extends across the midline to minimize in-field recurrences. Protocol PSA testing is performed every 6 months and MRI monitoring is performed at 6 months, 2, 3.5, 5, 7.5, and 10 years. We have previously reported that biopsy is safely avoided if the MRI is not suspicious for in-field or out-of-field disease recurrence. The few cases of MRI invisible clinically significant disease exhibited low volume Gleason pattern 4 and were often managed with active surveillance.
By consensus, the ideal candidate for focal ablation has intermediate favorable risk disease associated with an MRI target, no contralateral GG2 disease, no gross extracapsular extension, and no distal apical extension of the MRI target. In many of these cases, active surveillance is inadequate treatment, whereas whole gland treatment with radical prostatectomy or radiation therapy is excessive treatment.
We have previously reported our 6-month, 2-year, and 5-year oncological outcomes following focal cryo-ablation of intermediate risk disease, which included both GG2 and GG3. In our recent publication in Urology, we report 7-year oncological outcomes on 276 men with GG2 disease enrolled in our clinical trial. One of the many strengths of our study is the 91% compliance with our rigorous MRI surveillance protocol.
We defined clinically significant disease recurrence as any Gleason pattern 4 on surveillance biopsy, realizing that active surveillance represents a very reasonable option for very low volume Gleason pattern 4. We defined freedom from failure as no whole gland salvage treatment, development of metastasis, or prostate cancer mortality
The total csPCa recurrence free survival at 3, 5, and 7 years was 90.20%, 78.36%, and 70.31%, respectively. The rates of in-field and out-of-field csPCa recurrence were similar. The freedom from failure at 3, 5, and 7 years was 95.4%, 85.7%, and 84.3%, respectively. There were no prostate cancer mortalities and only 3 developed metastases. None of the subjects experienced any level of urinary incontinence, rectal injury, or received neoadjuvant ADT. None of the men were admitted post-operatively or within 30 days of treatment. A multivariate analysis was performed to identify demographic, imaging, or biopsy characteristics predicting csPCa recurrences. African American race was the only significant independent predictor for developing a csPCa recurrence.
The present study supports focal cryo-ablation as a very reasonable option for men with intermediate favorable risk prostate cancer associated with an MRI target with no evidence of extra-capsular extension or distal apical disease on MRI, and no contralateral GG> 1 disease. Focal cryo-ablation may be the preferred shared decision treatment option for these men when both the patient and surgeon/radiation oncologist are concerned that AS represents under-treatment and RP/RT over-treatment. In one of the authors' practices, which includes having performed 5000 radical prostatectomies, 80% of men with focal intermediate risk prostate cancer will choose focal cryo-ablation over active surveillance or whole gland treatment options.
Written by: Herbert Lepor,1 Jared Fiske,1 Majlinda Tafa,1 Elizabeth Pirraglia,2 James S Wysock,1
- Department of Urology, NYU Grossman School of Medicine, New York, NY
- Department of Population Health, NYU Grossman School of Medicine, New York, NY