Treating prostate cancer by thermal ablation uses extreme heat or cold to destroy the tissue. Prostate ablation was originally performed as a radical (total gland) treatment because prostate cancer was considered a multifocal disease. In other words, ablation was used as a substitute for surgical removal (prostatectomy) or radiation of the whole gland. It wasn’t long, however, before a handful of interventional radiologists and urologists saw the potential for directing a controlled ablation at just the tumor, called focal treatment. Focal ablation only began to be accepted as a standard of care, however, with two other scientific contributions:
1. New evidence from pathology regarding the incidence of unifocal disease (only one significant tumor), and
2. Improvements in imaging that allowed better biopsy information, treatment guidance, and real-time verification of treatment effectiveness.
When all of this fell into place, focal therapies gained wide acceptance for treating primary (first-time) prostate cancer tumors.
More recently, another focal treatment has been quietly evolving. It concerns prostate cancer patients whose primary treatment was radiation, but their cancer has recurred (come back). Since the early 2000’s, whole-gland salvage ablation has been increasingly accepted as a potentially curative alternative to salvage prostatectomy, a difficult surgery with a high rate of side effects due to the radiation damage to neighboring structures. Still, whole-gland salvage ablation has more side effects than whole-gland primary ablation for the same reason. Inevitably, a small number of physicians began to apply the principles of focal therapy to salvage ablation. As with most medical advances, these early users of focal therapy were geographically scattered, and more or less “inventing” their protocols as they went along—though eagerly following each other’s methods and progress. Today, there are some published studies based on very small patient series or on registry data, but evidence from true clinical trials is in short supply. Such trials are needed, because focal salvage ablation may prove to be at least as effective as radical salvage ablation, but with significantly fewer side effects.
In July, 2014, I blogged about the Delphi method for achieving collective agreement, and I described how an international group of experts achieved consensus on designing clinical studies on focal ablation of primary prostate cancer (https://sperlingprostatecenter.com/panel-reaches-consensus-focal-therapy-trial-design/). I just read an article on the Delphi method used by another expert group in order to design focal salvage trials to “address the aspects of accepted standards in the initial evaluation, treatment, follow-up, and outcomes…” After three rounds of questionnaires to 71 participants, an in-person meeting was held to identify points of agreement. Among their clinical study guidelines, they noted: “The optimal biopsy strategy is image-guided targeted biopsies. Follow-up includes multiparametric magnetic resonance imaging, prostate-specific antigen level, and quality of life for at least 5 years.”
Focal salvage ablation is a true blessing for qualified radiation-recurrent patients. Historically, the overwhelming majority of these men were almost automatically placed on hormone ablation before the advent of whole-gland salvage ablation. This meant they had no hope of cure, and the years that were added to their lives were marred by the unpleasant side effects of “chemical castration.” At our Center, we are happy that we have state-of-the-art resources for the early detection and diagnosis of localized recurrence after radiation, when it is still amenable to focal ablation (provided the patient is a candidate according to all criteria). Thanks to the new guidelines produced by the experts who used the Delphi method, our imaging services can conform with and serve well-designed studies of focal salvage ablation.
i Van den Bos W, Muller BG, de Bruin DM, de Castro Abreu AL et al. Salvage ablative therapy in prostate cancer: International multidisciplinary consensus on trial design.Urol Oncol. 2015 Jul 28. pii: S1078-1439(15)00324-5. doi: 10.1016/j.urolonc.2015.06.015. [Epub ahead of print]