Percutaneous MR-guided whole-gland prostate cancer cryoablation: safety considerations and oncologic results in 30 consecutive patients

Abstract

Objective: To assess the safety and oncological efficacy of percutaneous MR-guided whole-gland prostate cancer (PCa) cryoablation (CA).

Methods and materials: Between July 2009 and January 2018, 30 patients (mean age 72.9 ± 5.13 years) with histologically proven, organ-confined (≤ T2cN0M0), predominantly low/intermediate-risk PCa (median Gleason score 7; mean prostate specific antigen 6.05 ± 3.74 ng ml^-1 ) underwent MR-guided whole-gland CA. Patients were selected on the basis of prior pelvic radiotherapy (n = 16; 12 for previous PCa), or contra indication/refusal of surgery or radiotherapy. Complications, local progression-free survival (LPFS) and overall survival (OS) were retrospectively investigated.

Results: Eighteen [60%] patients reported procedure-related complications: 5/18 [28%] needed surgical/interventional treatments and 13 [72%] conservative or pharmacological treatment. Eleven [73%] complications were noted in the first 15 patients and 7 [47%] in the last 15 patients (p = 0.26). Mean nadir prostate specific antigen was 0.24 ± 1.5 ng ml^-1 (mean follow-up 3.8 years; range: 2 - 2915 days). Seven [23%] patients developed histologically proven local progression (mean time to recurrence 775 days, range: 172 - 2014). Mean clinical follow-up was 3.8 years (range 1-2915 days). LPFS was 92.0, 75.7 and 69.4 % at 1-, 3- and 5 year follow-up, respectively. For patients in salvage treatment, LPFS was 100%, 75%, and 75% at 1-, 3- and 5 year follow-up. OS was 100%, 94.4 and 88.5 % at 1-, 3- and 5 year follow-up respectively, with no patients dying from PCa.

Conclusion: Whole-gland PCa CA offers good oncological efficacy, particularly in post-radiotherapy cases. Although the complication rate is significant, the majority is minor and is managed with conservative or pharmacologic management.

Advances in knowledge: MRI-guided whole-gland prostate cancer cryoablation offers good oncological efficacy, particularly in post-radiotherapy cases with a contained complication rate.

Figure 1.

Current patient preparation and positioning before cryoprobes insertion. After general anesthesia and antibiotic administration, a dissection of the Denonvillier’s fascia is performed under ultrasound guidance (A). Autologous blood injection (B) allows a reversible but long-lasting enlargement of the recto-prostatic space. The ultrasound probe and the needle are then withdrawn, the grid is placed on its support and the patient is draped sterile (C).

Figure 2.

Intraprocedural MRI monitoring during whole-gland CA procedure. Following placement of the urethral warming catheter, dissection of the recto-prostatic space and placement of thermocouples, the patient is installed on the MRI table and multiplanar T2 images are acquired. In this patient, Axial (A) and Sagittal (B) T2 TrueFISP images demonstrate intermediate-signal fluid in the recto-prostatic space (arrows) following initial hemodissection. Cryoprobes are then inserted under MR fluoroscopy; and a 3D T2 SPACE sequence is acquired to check probe placement (arrows) in the axial (C) and Sagittal (D planes. During the freezing cycles, T2 space acquisitions are regularly obtained to evaluate the extension of the iceball. Axial (E) and Sagittal (F) 3D T2 SPACE reconstructed images showing the largest ice-ball size obtained at the end of the second freezing cycle; as clearly shown the posterior margins of the ice-ball (arrows) are relatively distant from the anterior rectal margin (arrowhead). 3D, three-dimensional; CA, cryoablation.

Figure 3.

Overall local progression-free survival of all patients undergoing MR-guided whole-gland CA of PCa in the study population (solid line; 95% CI, dotted lines). CA, cryoablation; CI, confidence interval; PCa, prostate cancer.

Figure 4.

Local progression-free survival in primary treated patients (dotted line) or in salvage therapy (solid line).

Figure 5.

Overall survival in the study population (solid line; 95% CI dotted lines). CI, confidence interval.

Figure 6.

MRI follow-ups in the same patient showed in Figure 2. Axial T2 (A), Sagittal T2 (B), and Axial contrast-enhanced T1 fat-saturated (C) sequences obtained at 1 month follow-up show heterogeneous high signal throughout ablated volume (arrows in A, B) and absence of contrast-enhancement in the center of the ablated volume, consistent with necrotic changes; a peripheral posterior rim of contrast enhancement is noted (arrowhead in C), consistent with early physiologic inflammatory changes. The same MRI sequences acquired at 12 month follow-up (D–F) demonstrate significant fibrotic shrinkage of the ablated volume without significant contrast-enhancement thus being consistent with a complete ablation of the entire prostatic tissue; the central focal signal on contrast-enhanced T1 fat-saturated sequence (arrow in F) corresponds to urethra.