Reply to Pirus Ghadjar and Thomas Wiegel's Letter to the Editor re: Daniel E. Spratt, Robert T. Dess, Zachary S. Zumsteg, et al. A Systematic Review and Framework for the Use of Hormone Therapy with Salvage Radiation Therapy for Recurrent Prostate Cancer. Eur Urol. In press. http://dx.doi.org/10.1016/j.eururo.2017.06.027: Salvage Radiotherapy and Hormone Therapy: Change Is Coming, Just Not Quite Yet.

Drs. Ghadjar and Wiegel bring up excellent points regarding the use of molecular imaging in the context of salvage radiotherapy (SRT), the potential benefits of dose-escalated SRT, and the use of targeted radiotherapy to all metastatic sites without androgen deprivation therapy (ADT). These ideas may translate into improved outcomes for patients with recurrent prostate cancer. However, the framework put forth by our multidisciplinary group on when to initiate hormone therapy with SRT was built upon level 1 evidence [1]. There are no long-term data or reported randomized data to demonstrate that any of the strategies suggested by Drs. Ghadjar and Wiegel will improve clinically meaningful endpoints, such as metastasis-free survival, prostate cancerspecific survival, or overall survival. This prevents us from providing formalized recommendations regarding these exciting approaches. Fortunately, multiple ongoing and completed randomized phase 2 and 3 trials are going to test these hypotheses. As Drs. Ghadjar and Wiegel outlined, multiple studies have nicely demonstrated that molecular imaging can readily identify positron emission tomography (PET)–avid sites of disease outside of standard radiotherapy fields in men with recurrent prostate cancer [2]. Unfortunately, PET has a limit of detection of 2–4 mm and is unable to identify micrometastatic disease. Given that the most common site of recurrence after surgery is local, prostate bed radiotherapy should not be omitted at this time. Therefore, the knowledge that molecular imaging provides does not immediately alter our recommended treatment paradigm on the use of ADT with SRT, but may in the future impact extended radiotherapy field design with the increasing widespread use of molecular imaging.