MR-guided focal cryoablation is feasible and safe for treating recurrent prostate cancer after radiotherapy, representing a new option to combat the disease, according to a small study published in the August issue of Radiology.
Cryoablation using MR imaging for guidance sidesteps some of the issues inherent in the use of ultrasound guidance, and can reduce hospitalization compared with salvage radical prostatectomy, explained Joyce G. R. Bomers, MSc, and colleagues from Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands. Transrectal ultrasound guidance, while an established option, cannot accurately localize prostate cancers and is limited in monitoring the ice ball during the cryoablation process. Patients who undergo radical prostatectomy instead of cryoablation can expect to be hospitalized up to two weeks, while most of the patients in the current study were discharged one day following MR-guided focal cryoablation.
Bomers and colleagues assessed MR-guided focal cryoablation through a prospective study of 10 consecutive patients with histopathologically proven recurrent prostate cancer after radiotherapy. All patients were without evidence of distant metastases and were treated under general anesthesia using a 1.5-T MR scanner.
The only other preliminary investigations into the use of MR-guided cryoablation in prostate cancer have used a whole-gland approach, unlike the focal treatment conducted in the current study, which ablates only the lesion and a safety margin surrounding it.
“By applying focal treatment, we aimed to keep to a minimum complications such as incontinence, impotence, and rectal fistula formation,” wrote the authors. “In addition, as a consequence of focal ablation, fewer needles (2–4) were needed per patient.”
Bomers and colleagues explained the process begins with insertion of a urethral warmer, then cryoneedles were transperineally inserted under real-time MR imaging. A rectal warmer is then inserted. Ice ball growth is continuously monitored by MR. A total of two free-thaw cycles were performed.
All patients were successfully treated, and most without significant complications, reported the authors. Eight patients were discharged after one day, but in one patient, the urethral warmer could not be inserted and the procedure was canceled and rescheduled (and successfully completed) two months later. One patient had urinary retention.
Local recurrence or remnant tumors were spotted in two patients at six months follow-up, and in a third patient at 12 months. All three of these patients were later successfully retreated using MR guided focal cryoablation.
While the results are promising, Bomers and colleagues called for more studies with longer follow-up and more patients.