SIR 2009: Focal Cryoablation Safe and Effective for Treating Prostate Cancer

Roxanne Nelson

March 10, 2009

March 10, 2009 (San Diego, California) — Focal cryoablation represents a middle ground between watchful waiting and aggressive radical treatments for prostate cancer, and results in a low rate of disease recurrence and low morbidity, according to data presented here at the Society of Interventional Radiology (SIR) 34th Annual Scientific Meeting.

I think we truly have a minimally invasive treatment for prostate cancer.

"I think we truly have a minimally invasive treatment for prostate cancer," said lead author Gary M. Onik, MD, interventional radiologist and director of the Center for Safer Prostate Cancer Therapy, in Orlando, Florida. "We can have patients treated on an outpatient basis, have an extremely rapid recovery, and potency returns extremely quickly, if it's affected at all."

Dr. Gary Onik

Dr. Onik presented results for a series of 120 men who underwent focal cryoablation during a 12-year period. After a mean follow-up of 3.6 years, the majority of these men (112 patients, 93%) have stable prostate-specific antigen levels and no evidence of cancer. Within this cohort, 72 patients were considered at medium to high risk for recurrence, he said.

Morbidity was also low, and sexual potency was maintained in 85% of patients who were potent before the procedure. All patients who did not have previous prostate surgery remained continent.

"We need to validate the data, but it is extremely promising," Brian Stainken, MD, president-elect of SIR, told Medscape Oncology. "In the past, approaches to treating prostate cancer have involved the entire gland — whether it was freezing it, radiating it, or removing it. This new targeted approach makes fundamental sense."

Focal cryoablation has been shown to be as effective as other prostate cancer treatments, but has the benefit of being less invasive and traumatic for patients and is not associated with any major complications, Dr. Onik noted.

"What we have proven with this study, and other studies that are out there, is that patients should be perfectly comfortable choosing this as a first-line option and that it is as effective as surgery or radiation," he said.

Many patients with prostate cancer are being overtreated, especially with procedures that are associated with significant morbidity, Dr. Onik said during a press briefing. At the other end of the spectrum is watchful waiting, but some patients are not comfortable with this strategy and will proceed to aggressive therapy, he added.

Male Version of Lumpectomy

The idea for a more middle-ground approach to prostate cancer treatment came from the use of lumpectomy in breast cancer, which has now become a standard treatment. "Women were once in the same position that men are in now, when the standard treatment for breast cancer was radical mastectomy," said Dr. Onik. "Breast cancer treatment has evolved over time to less invasive therapies, but prostate cancer therapy has not. The idea was to take what occurred in breast cancer therapy and apply it to men."

Focal cryoablation can be considered "a male version of lumpectomy," in that just a portion of the prostate gland is treated, he said. It spares as much of the prostate as possible, along with its neurovascular bundles, thus limiting adverse effects such as erectile dysfunction and incontinence. It also represents an advantage over watchful waiting, because it removes the tumor and preserves all future treatment options.

None of the patients developed local recurrences in the treated areas, and the 7% of men who did develop cancer at a different site were successfully retreated, said Dr. Onik.

3D-Mapping Biopsy Improves Accuracy

In a related study, Dr. Onik and colleagues also showed that the 3D-transperineal-mapping biopsy is more accurate than the standard transrectal ultrasound (TRUS) biopsy for staging prostate cancer, and that it complements the focal cryoablation approach.

The 3D-mapping biopsy allows many more samples to be obtained than a conventional biopsy, and it also makes it possible to accurately map the location of each biopsy core removed.

"TRUS is a poor way of staging, and we have come up with a much more accurate method of staging, as 3D mapping allows us to pinpoint exactly where the cancer is," said Dr. Onik. "This accuracy is what allows us to do focal therapy. But even if a patient doesn't want focal therapy, it allows us to give them a more efficacious approach to any therapy."

In this study, the results with 3D-prostate-mapping biopsy were compared with results obtained with traditional TRUS biopsy, and its possible impact on patient management was assessed.

The cohort consisted of 180 patients with unilateral cancer on TRUS biopsy who were considering conservative management and who underwent restaging with 3D-transperineal-mapping biopsy. Results showed that 110 patients (61.1%) had bilateral cancer, even though TRUS biopsy showed that they only had cancer on 1 side. The Gleason scores of 41 patients (22.7%) increased to 7 or higher, and 36 patients had negative results on 3D mapping. Overall, 70% of the men would have had their management changed by the information provided by 3D mapping.

"TRUS biopsy is currently the gold standard, despite the fact that we have known for decades that this is not an accurate way of staging prostate cancer," said Dr. Stainken. "But it was the only method we had and it became the gold standard for making therapeutic decisions. The problem is that now there's more than 1 approach to treating prostate cancer, and proper staging has become increasingly important."

Dr. Onik discloses a relationship with Bostwick Labs and an ownership interest in Endocare Inc.

Society of Interventional Radiology (SIR) 34th Annual Scientific Meeting: Abstracts 75 and 198. Presented March 9, 2009.

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