The feasibility and safety of repeat cryosurgical ablation of localized prostate cancer

Focal cryotherapy for prostate cancer: a contemporary literature review

Objective

To perform a comprehensive review of the contemporary literature regarding both functional and oncologic outcomes after primary focal cryotherapy for prostate cancer (PCa), providing these results as a foundation for discussing recent developments in the realm of focal therapy.

Background

Traditional treatments for PCa are often associated with debilitating functional side effects for patients. Due to advances in imaging and biopsy strategies, focal ablative therapies recently have garnered much interest and offer an alternative primary treatment for PCa patients with localized disease. Focal cryoablation utilizes heat extraction from tissues to generate an iceball and cause tissue destruction while sparing uninvolved prostatic regions. Optimized patient selection and postoperative management continue to be areas of interest and study as the field continues to develop.

Methods

A search was performed of the PubMed and Embase databases to identify articles pertaining to primary focal PCa cryoablation since our group's last comprehensive review in 2016.

Conclusions

Primary focal cryoablation for PCa offers optimized functional outcomes and a favorable adverse event profile. True evaluation of oncologic outcomes is hampered by lack of long-term follow-up and highly variable clinical endpoints across these studies. Nonetheless, outcomes appear adequate in the short- to medium-term time frame. Utilization of focal cryoablation is expected to grow with continued refinement of patient selection and management options in cases of treatment failure.

Partial Gland Ablation of Prostate Cancer: Effects of Repeat Treatment

OBJECTIVE

To evaluate the near-term clinical and pathological effects of repeat partial gland ablation (PGA) in men with intermediate-risk prostate cancer (PCa).

MATERIALS AND METHODS

One hundred seventy men with focal lesions of PCa (all GG2 or GG3) underwent PGA with high-intensity focused ultrasound (HIFU) or cryotherapy (CRYO) in prospective trials. Residual PCa in or near the ablation zone was found in 37 men after a first PGA; 30 went on to receive a second PGA and were the subjects of study. At 3 timepoints, baseline and 6 months after first and second ablations, quality-of-life (QOL) questionnaires (IIEF, IPSS) and MRI-guided biopsies (MRGB) were performed. Biopsies were targeted and systematic at baseline and in follow-up, comprehensively about the ablation zone.

RESULTS

All 30 patients completed QOL questionnaires and 26 had MRGB at the 3 timepoints. Mean QOL scores were not significantly different from the baseline after the first or second PGA. No operative complications were encountered; and "decisional regret" was reported in only 2/29 men after the repeat ablation. A decrease in semen volume was reported by 25% of patients. Repeat ablation was successful (absence of csPCa on MRGB) in 14/26 (53%) of men. PSA levels decreased and MRI lesions resolved after ablations, but neither was a reliable predictor of biopsy outcomes.

CONCLUSION

When initial PGA fails, repeat PGA is a reasonable consideration, because in near-term follow-up, secondary procedures appear to be safe, causing only minimal detriment to urinary and sexual function, with csPCa becoming undetectable by MRGB in approximately half the patients.

Oncological outcomes of salvage cryotherapy after primary radiation therapy vs. primary cryotherapy: 10-year experience at a large Canadian referral center

INTRODUCTION

Salvage cryotherapy is a guideline-recommended treatment of localized prostate cancer recurrence after radiation therapy. There is little published evidence analyzing the outcomes of salvage cryotherapy for recurrent prostate cancer following different primary therapy energy modalities.

METHODS

We performed a retrospective analysis of patients who received whole gland salvage cryotherapy from 2007-2017 at a large tertiary referral center after either primary radiation therapy (RT) or primary whole gland cryotherapy. Primary outcome was biochemical failure, defined as per the Phoenix criteria (prostate-specific antigen [PSA] nadir + 2.0 ng/ml). Secondary outcomes included time to biochemical failure and development of metastatic disease.

RESULTS

Fifty-eight of 391 patients who received cryotherapy were identified as having received salvage cryotherapy (after RT, n=37; after primary cryotherapy, n=21). Biochemical recurrence occurred in 21 (57%) patients with previous RT and in 17 (81%) patients with previous cryotherapy (p=0.001). Median time to biochemical recurrence was 18 months for patients with previous RT and 13 months for patients with previous cryotherapy (p=0.002). The biochemical-free survival rate for primary radiation therapy patients was 71% at two years compared to 23% at two years for patients who underwent primary cryotherapy (p<0.01). There was no difference in the development of metastatic disease between groups (19% vs. 18%, cryo vs. radiation, p=0.34).

CONCLUSIONS

These results suggest that salvage cryotherapy may offer more durable oncological control to patients after radiation compared to primary cryotherapy, with a lower rate and longer duration before biochemical recurrence.

Prostate Multiparametric Magnetic Resonance Imaging Features Following Partial Gland Cryoablation

OBJECTIVE

To assess the qualitative and quantitative changes on prostate multiparametric magnetic resonance imaging (mpMRI) following partial gland ablation (PGA) with cryotherapy and correlate with histopathology.

METHODS

We used 3D Slicer to generate prostate models and segment ipsilateral (treated) and contralateral peripheral and transition zones in 10 men who underwent MRI/transrectal ultrasound fusion-guided PGA during 2017-2018. Pre- and post-PGA volumes of prostate segments were compared. Post-PGA mpMRI were categorized according to PI-RADS v2 and treatment response on mpMRI was assessed in a manner similar to the radiology evaluation framework following liver lesion ablation.

RESULTS

Median volume of ipsilateral peripheral and transition zones decreased from 10.9 mL and 13.0 mL to 7.2 mL and 10.8 mL (P = .005), respectively. Median volume of contralateral peripheral and transition zones also decreased from 12.1 mL and 12.5 mL to 9.9 mL to 10.4 mL (P = .005), respectively. Five men had clinically significant disease (Grade group ≥2) on post-PGA biopsy (3 within treatment field and 2 outside). Of the men with clinically significant prostate cancer, mpMRI revealed PI-RADS 3 lesions in 2. However, the treatment response framework did not detect residual disease.

CONCLUSION

PGA results in asymmetrical and significant reductions in prostate volume. Our results highlight the need for a separate assessment framework to enable standardization of the interpretation and reporting of post-PGA surveillance mpMRI. Moreover, our findings have significant implications for MRI-targeted surveillance biopsy following PGA with cryotherapy.