Transrectal implantation of electromagnetic transponders following radical prostatectomy for delivery of IMRT

Surgical treatment for men with localized prostate cancer -open, laparoscopic, or robotically-assisted-- remains one of the therapeutic mainstays for this group of patients. Despite the stage migration witnessed in patients with prostate cancer since the introduction of prostate-specific antigen (PSA) screening, detection of extraprostatic disease at the time of surgery and biochemical recurrence following prostatectomy pose significant therapeutic challenges. Radiation therapy (RT) after radical prostatectomy (RP) has been associated with a survival benefit in both the adjuvant and salvage setting. Nevertheless, optimal targeting of the prostate bed following surgery remains challenging. The Calypso 4D Localization System (Calypso Medical Technologies, Seattle, WA, USA) is a target positioning device that continuously monitors the location of three implantable electromagnetic transponders. These transponders can be placed into the empty prostatic bed after prostatectomy to facilitate the delivery of radiation therapy in the postsurgical setting. In this article, we detail our technique for transrectal placement of electromagnetic transponders into the postprostatectomy bed for the delivery of adjuvant or salvage intensity-modulated radiation therapy. We prefer this technique of post-surgical radiation therapy because it allows for improved localization of the target area allowing for the maximal delivery of the radiation dose while minimizing exposure of surrounding normal tissues. Although emerging, our initial oncologic and functional outcomes have been promising.