Saline hydrodissection is promising addition to prostate cancer cryotherapy
MedWire News: US researchers report that using active hydrodissection – a technique involving a saline injection to the prostate and rectum during cryoablation for prostate cancer – helps reach lethal prostate temperatures, while simultaneously protecting the rectal wall.
Current cryosurgical ablation techniques aim to achieve the maximal effect by reaching temperatures of 0°C in the prostate, whereas the current study reports temperatures below -40°C being repeatedly achieved without risk to the rectal wall.
“Active hydrodissection appears to be a powerful tool to improve the lethal temperatures achieved in the prostate and to safely move the rectal wall from harm’s way,” say Gene Rosenberg and Kevin Basralian from Hackensack University Medical Center in New Jersey.
The team carried out active hydrodissection in a group of 10 consecutive localized prostate cancer patients who underwent cryoablation (two active freezes of the anterior and posterior, followed by two thaws) as total therapy (n=5, up to 8 cryoprobes), subtotal therapy (n=4, 5–7 cryoprobes), or focal therapy (n=1, 3 cryoprobes).
Patients had pre-operative prostate specific antigen (PSA) levels ranging between 2.3 and 37.4 ng/ml.
The men underwent temperatures of -10°C to -76°C during each freeze. Hydrodissection was used to push the rectal wall away from probes 3–6 during the posterior freeze, and treatment was considered complete when ultrasound scans revealed 4 mm of ice beyond the prostatic capsule, or thermocouple measurement of -30°C or less in the prostatic capsule was achieved.
Follow-up ranged between 2 and 9 months, during which time all patients were fully continent. Post-treatment PSA levels were greatly reduced, ranging from less than 0.1 ng/ml in one patient who received subtotal therapy, to 3.4 in the patients who underwent focal therapy.
Overall, one patient developed a rectal fistula 2 months after treatment, note the researchers, which was treated effectively by catheter drainage. The remaining 9 patients received 5 minutes of further hydrodissection after the second active thaw and no further fistulae developed.
Urethral sluff also developed in two patients when the urethra was too close to the cryoprobe. However, in both cases, less than 5% of the urethral lining was involved, and the researchers believe the problem could be avoided by increasing the cryoprobe-to-urethra distance or decreasing the intensity of the cryoprobe energy.
“This technique appears to hold great promise and should be investigated further in a larger group of patients with longer follow-up,” conclude Rosenberg and Basralian in the journal Urology.
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By Sarah Guy