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Focal Cryotherapy for clinically significant prostate cancer: Oncological and functional outcomes of a prospective observational extension of a Phase II clinical trial

X. Yang¹, Y. Tan¹, T. Lu¹, X. Sim¹, K. Chen¹, J. Yuen¹, C. Cheng¹, H. Ho¹, Y. Law², K. Tay¹

¹Singapore General Hospital, Urology, Singapore, Singapore
²Singapore General Hospital, Diagnostic Radiology, Singapore, Singapore

Introduction:

We describe oncological and functional outcomes of a prospective cohort of men undergoing focal therapy (FT) for clinically significant prostate cancer (csPCa).

Material and methods:

This is a single-centre, prospective observational extension of a phase II clinical trial that recruited patients with PSA ≤15, grade-group (GG) ≤4, single lesions of 3 ml, or up to 2 lesions of maximum volume 1.5 ml for focal cryotherapy. Repeat multiparametric magnetic resonance imaging (mpMRI, MRI-targeted and systematic saturation biopsy were mandated at 12 months, and mpMRI with for-cause biopsy 2-yearly thereafter. Recurrence, any biopsy-detected csPCa, was classified into infield (within the treated area) or outfield (outside the treated area) recurrence. Complications were recorded using the Clavien-Dindo system. Quality of life was assessed using the expanded prostate composite index (EPIC) questionnaire at baseline, 1, 3, 6, 12, 18, 24, 30, and 36 months.

Results:

80 patients completed minimum 1-year follow-up and had a median follow-up of 36 months. Median PSA was 6.8 ng/dl. 62/80 (77.5%) patients had GG 2, 13/80 (16.3%) GG3, and 5/80 (6.3%) GG4 prostate cancer. The median csPCa volume was 0.69 ml. No Clavien-Dindo grade ≥2 complications were recorded. 66/80 (82.5%) patients were free of csPCa at 1-year and 26/38 (68.4%) at 3-years after FT. Of 80 patients reaching 1-year, 78/80 (97.5%) complied with mandatory mpMRI, and 70/80 (87.5%) complied with mandatory rebiopsy. 5/80 (6.3%) patients had infield csPCa recurrence, and 10/80 (12.5%) had outfield csPCa recurrence. Of the 38 patients reaching 3-years, the 1-year csPCa recurrence rate was 8/38 (21.1%), with 4/38 infield and 5/38 outfield, and a 3-year csPCa recurrence rate of 13/38 (34.2%), with 7/38 infield and 8/38 outfield. Treatment-free survival was 73.7%, and radical treatment-free survival 92.1% at 3 years. 9 patients had repeat FT, 3 had radical prostatectomy and 4 had radiotherapy. Of 29/80 (36.3%) patients with good-moderate baseline sexual function, significant deterioration was seen at 1-month post-treatment (mean reduction score of -22.1, p<0.001) which returned to baseline by 12 months. Ablation close to or involving one neurovascular bundle was associated longer reductions in sexual function. Transient worsening of urinary and bowel function was only observed at 1‐month post-treatment and returned to baseline thereafter.