TAMPA, Fla.—Magnetic resonance (MR)-guided ablative therapy using laser thermal energy or cryoablation could provide another option for treating locally recurrent prostate cancer after radical retropubic prostatectomy (RRP), results from a pilot study suggest.

“Magnetic resonance-guided ablation may prove to be a promising new treatment for prostate cancer recurrences. It tailors treatment modality and duration to lesion size and location and provides a less invasive and minimally traumatic alternative for men,” said lead investigator David Woodrum, MD, PhD, an interventional radiologist at Mayo.

He presented the findings from the first known patient cases using MR-guided ablative therapy for recurrent prostate cancer at the Society of Interventional Radiology annual meeting. In a collaborative effort between urologists and interventional radiologists, a pilot study was undertaken with four patients who had locally recurrent prostate cancer following RRP. All four men underwent salvage therapy with either MR-guided laser interstitial thermal therapy (two men) or cryoablation (two men). 

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Clinicians tailored treatment to lesion size and location using MR imaging with temperature mapping and/or ice ball growth monitoring. The four patients had no known metastases at the time of treatment. The clinicians used an MR-compatible urethral cooling catheter to prevent urethral thermal damage during the ablation. “Immediately after treatment, we found no definitive residual tumor. The treatment preserved the patients’ baseline sexual and urinary function and had no major complications,” Dr. Woodrum said.

The four cases demonstrate the feasibility and safety of MR-guided ablation in the post-surgical prostate bed, said co-investigator Lance Mynderse, MD, a Mayo urologist. Additional research is needed to determine which patients may be best suited for the ablation procedures and to examine middle-term and long-term results for efficacy, he said.

In this retrospective review, each of the four men was found to have post-surgical recurrent prostate cancer detected by MR imaging and proven with biopsy. 

Two of the men were treated with MR-guided laser interstitial thermal therapy. The other two were treated with cryoablation. 

The biopsy-proven cancer lesions ranged in size from 6- 17 mm and were located in the prostate bed just inferior to the bladder and anterior to the rectum, where the prostate gland had previously resided.  For both ablation methods, interventionalists used two to three probes or applicators. No residual tumor demonstrated on immediate post-ablation imaging.