A "male lumpectomy" procedure presented on at SIR offers a non-surgical treatment for prostate cancer that also preserves urinary and sexual function in a majority of men.
The procedure uses focal cryoablation - freezing the tissue with extremely cold gas - to target only the tumour itself, which spares the healthy tissue in and around the prostate gland, rather than destroying all of it, as the traditional approaches do.
Study author Dr Gary Onik, of Florida Hospital/Celebration Health, Celebration, Florida, pioneered prostate cancer cryoablation in the early 1990s - his own best friend being among the first nine patients on whom he performed the procedure.
At SIR, Onik discussed his ongoing study of 60 patients treated with focal cryoablation. The preliminary results for the 42 men who completed between one-year and eight years follow-up showed 95% (40) had stable prostate-specific antigen tests, showing no evidence of cancer. High rates of potency were also maintained. Of the 32 patients who were potent prior to the procedure, 78% (25) remained potent afterwards. This compares with 20-40% potency rates in patients who are treated with unilateral nerve-sparing radical prostatectomy and 50% long-term potency rates for radiation therapy, including brachytherapy.
No patient reported incontinence - something Onik said for many is a more important side effect than impotence.
Onik refers to focal cryoablation treatment for prostate cancer as "male lumpectomy," reflecting the origins of the approach in the breast-sparing surgery that has in recent years replaced radical mastectomy as the preferred treatment for breast cancer. Non-surgical cryoablation spares as much as possible of the prostate gland and its neurovascular bundles, limiting side effects of incontinence and impotence that can result from more radical prostate cancer treatments, such as surgical prostatectomy. It also represents an advantage over "watchful waiting," because the surgical option is preserved, but the risk of missing the treatment window early in the cancer's progression is lower.
Onik also presented on a new image-guided interventional biopsy method which he described as dramatically more accurate that the current transrectal ultrasound (TRUS) biopsy method and providing improved staging of prostate cancer and therapeutic decision making.
In this technique, a grid placed over the perineum (the area of skin between the rectum and the scrotum) allows the physician to accurately map the location of each biopsy core removed. Further, the cores are taken through the skin rather than through the rectum, allowing many more cores to be removed - up to 75 compared to 6-12 in a TRUS biopsy. This greatly increases the accuracy of the biopsy in diagnosing cancer - the technique caught tumours in over 50% of patients that had been inaccurately labelled negative by the old biopsy method. The mapping grid also allows the location of the tumour to be known much more precisely, allowing the interventional radiologist to cryoablate only the tumour and not the whole prostate gland.
Management of prostate cancer is in great part determined by the Gleason score, a cancer ranking method indicating tumour grade and stage, and the extent and location of the patient's disease. A high Gleason score or bilateral cancer may preclude brachytherapy. Location of cancer in areas close to the neurovascular bundle makes nerve-sparing radical prostatectomy not feasible.
In the study, 59 patients underwent transperineal mapping biopsies using ultrasound for guidance. Cores were removed from their prostates at 5mm intervals. Seventeen patients had bilateral biopsies and 42 had unilateral biopsies. Of the 42 patients who had had previously negative TRUS biopsies on one side (unilateral), 56% (23) were found to have cancer in the previously negative lobe. Of the 17 patients with bilateral biopsies, 15 had their treatment changed based on the new information from the biopsy. The new information provided by the biopsies had a major impact on cancer management for two-thirds of the patients.
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