SAN DIEGO, March 10 -- Prostate biopsies that sample tissue mapped in three dimensions may improve treatment planning and safely allow for a "lumpectomy" approach, researchers said.
Stage and grade revisions with 3-D mapping biopsy were substantial enough to change management for more than 70% of patients, compared with standard transrectal ultrasound (TRUS)-guided biopsy, according to Gary Onik, M.D., of Florida Hospital's Center for Safer Prostate Cancer Therapy in Orlando, and colleagues.
For tumors found with this more extensive biopsy method, targeted cryoablation achieved long-term local control without incontinence in all patients, according to a second study reported by the same group here at the Society of Interventional Radiology meeting.
Stage and grade revisions with 3-D mapping biopsy were substantial enough to change management for more than 70% of patients, compared with standard transrectal ultrasound (TRUS)-guided biopsy, according to Gary Onik, M.D., of Florida Hospital's Center for Safer Prostate Cancer Therapy in Orlando, and colleagues.
For tumors found with this more extensive biopsy method, targeted cryoablation achieved long-term local control without incontinence in all patients, according to a second study reported by the same group here at the Society of Interventional Radiology meeting.
"Almost every patient who is diagnosed with prostate cancer, except for those who, on their transrectal ultrasound biopsy, showed extensive high-grade disease, needs a mapping biopsy to fully evaluate their situation and treat them appropriately," Dr. Onik said.
Brian Stainken, M.D., of Roger Williams Hospital in Providence, R.I., and SIR president, agreed that the promising findings could be "game changing."
However, he sounded a note of caution in response to Dr. Onik's enthusiasm by emphasizing the need for further validation.
Dr. Onik, anticipating this argument, noted that the low morbidity rate -- no incontinence and 15% impotence in his study -- has been replicated in two other published studies.
These results were more impressive given that more than half of his 120 cryoablation patients with one to 13 years of follow-up were moderate- to high-risk or radiation failure cases, he said.
Likewise, morbidity was minimal with the 3-D mapping biopsy. The only complications were self-limiting hematuria (1.2%) and retention (7%).
These biopsies were done under transrectal ultrasound guidance, with tissue sampled every 5 mm throughout the prostate volume, using a brachytherapy grid. Careful labeling of specimen coordinates allowed the radiologist to reconstruct a detailed picture of the extent and location of the tumor.
Dr. Onik's group used this biopsy method for 180 men who were considering conservative management based on prior standard transrectal ultrasound biopsy that showed unilateral prostate cancer.
But the more extensive 3-D mapping biopsy showed bilateral disease in 55% of patients and increased the Gleason score for 22%.
The researchers estimated that at least 70% of the patients would have a change in therapeutic decision based on the more accurate staging.
It wasn't surprising that this technique beat transrectal ultrasound biopsy, Dr. Onik said. Although the gold standard for prostate biopsy, "we have known for decades that this is not an accurate way of staging prostate cancer," he said, "but it was the only thing we had."
In addition to helping patients decide between watchful waiting and more aggressive therapy, pinpointing the tumor can allow for a more nuanced treatment approach similar to the revolution in breast cancer surgery, Dr. Onik said.
"More than 25 years ago women were in exactly the same situation men are in now," he said. "The treatment was radical mastectomy."
With this as an inspiration, Dr. Onik's group started to pursue what he called "male lumpectomy" with focal cryoablation informed by 3-D mapping biopsy.
With this approach, their study showed that among the very high-risk radiation failure patients, 81% maintained stable prostate-specific antigen levels during follow-up after focal treatment.
In the total cohort, stable PSA rates with no evidence of cancer were reported for 93% by ASTRO criteria and 94% by Phoenix criteria.
Overall, eight patients were retreated to yield a 100% local control rate with targeted cryoablation.
Regardless of the risk level of prostate cancer patients, the biochemical recurrence rate did not climb over time and compared favorably to the 55% rate at 10 years in a prior study of high-risk patients who had radical prostatectomy.
Potency was maintained in 85% of patients potent prior to the procedure and of 120 patients without previous prostate surgery, all were continent (no pads).
Although local control has been thought to have little impact on overall survival in prostate cancer, Dr. Onik said that recent evidence has shown that better control of cancer in the prostate reduces risk of distant metastases and mortality.
The next step will be to compare "male lumpectomy" to robotic radical prostatectomy, he said.
Primary source: Society of Interventional Radiology
Source reference:
Onik G, et al "3D prostate mapping biopsy has a potentially significant impact on prostate cancer management" SIR 2009; Abstract 198.
Additional source: Society of Interventional Radiology
Source reference:
Onik G, et al "Focal therapy for prostate cancer -- 120 patients with up to 12-year follow-up" SIR 2009; Abstract 75.
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