Rectal Spacer Gel Displacement of the Rectum During Prostate Cryoablation: A Case Series

Purpose: To describe a novel case series using rectal spacer gel to displace and protect the rectum during prostate cancer cryoablation.Materials and Methods: Fifty men with clinically localized grade group 1–5 prostate cancer underwent concurrent rectal spacer gel and primary (n=27) or salvage (n=23) prostate cryoablation. Polyethylene glycol hydrogel (PEG; SpaceOAR, Boston Scientific, USA) or hyaluronic acid hydrogel (HAG; Barrigel, Pallette Life Sciences, USA) were used in 31 and 19 cases, respectively. Twenty-two of 50 patients (44%) had biopsy proven magnetic resonance imaging (MRI) visible tumor. Fifty-four percent of patients had involvement of the prostatic apex; the dominant MRI lesion measured an average of 12.0 (range, 5–25) mm. The primary outcome was rectal displacement measurement after gel insertion. Secondary outcomes include assessment of oncologic outcomes.Results: The median rectal displacement was 9 (range, 4.0–14.6) mm by intraoperative ultrasound or postoperative MRI. No significant difference in displacement was noted between primary or salvage, PEG or HAG. HAG delivery, sculpting ability, and ultrasound image degradation were more favorable compared with PEG. Due to increased rectal distance, iceball margins could be extended beyond the prostate capsule. No rectal fistulas were observed over a median follow-up of 253 (range, 8–1,157) days. One case of perineal cellulitis, classified as a Clavien-Dindo grade II complication, was observed. The median prostate-specific antigen (PSA) dropped to 2.78 ng/dL from a preoperative value of 5.33 ng/dL (p<0.0001); 5 of 52 patients (9.6%) had a higher PSA than pretreatment at last follow-up. Posttreatment biopsy was performed for rising PSA, detecting in-field recurrence in 3 patients (5.8%).Conclusion: Rectal spacer hydrogel at the time of prostate cryoablation achieved significant prerectal displacement potentially reducing the risk of collateral rectal injury and enabling more aggressive treatment margins.