11 C Choline- PET in prostate RT Influence of 11 C-choline PET/CT on the treatment planning for salvage radiation therapy in patients with biochemical recurrence of prostate cancer Michael Souvatzoglou a,⇑ , Bernd J. Krause a , Anja Pürschel b , Reinhard Thamm b , Tibor Schuster c , Andreas K. Buck a , Frank Zimmermann b , Michael Molls b , Markus Schwaiger a , Hans Geinitz b a Nuklearmedizinische Klinik und Poliklinik; b Klinik und Poliklinik für Strahlentherapie und Radiologische Onkologie; c Institut für Epidemiologie und medizinische Statistik, Technische Universität München, Germany article info Article history: Received 30 December 2009 Received in revised form 20 April 2011 Accepted 3 May 2011 Available online 26 May 2011 Keywords: 11 C-choline PET/CT Salvage radiotherapy Prostate cancer recurrence abstract Background and purpose: The present study evaluates the incidence of 11 C-choline PET/CT positive find- ings in patients with recurrent prostate cancer referred for salvage radiotherapy (SRT) and the influence on the definition of the planning target volume (PTV). Material and methods: Thirty-seven patients treated with radical prostatectomy and referred to SRT to the prostatic fossa because of biochemical relapse, were analysed retrospectively. All patients underwent 11 C-choline PET/CT before radiotherapy. The influence of PET/CT on the extent of the PTV was analysed. The median total follow up after SRT was 51.2 months. Results: 11/37 (30%) patients had a positive finding in the 11 C-choline PET/CT, 5 (13%) outside of the pros- tatic fossa (iliac lymph nodes), implicating an extension of the PTV. Patients with positive 11 C-choline PET/CT had a significant higher PSA value than patients with no pathologic uptake (p = 0.03). Overall, at the end of follow up 56% of the patients had a PSA 6 0.2 ng/ml and 44% had a biochemical relapse of prostate cancer. Conclusions: 11 C-choline PET/CT detects abnormalities outside of the prostatic fossa in 13% of patients referred for SRT because of biochemical relapse after radical prostatectomy, affecting the extent of the PTV. Prospective studies need to be implemented to evaluate the benefit of SRT with a PTV based on 11 C-choline PET/CT. Ó 2011 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 99 (2011) 193–200 Radiation therapy and radical prostatectomy are the two cura- tive treatment options for prostate cancer. Radical prostatectomy (RP) is the most widely used treatment for patients with localised prostate cancer. Approximately 20–30% of these patients will experience biochemical recurrence of their disease, manifested as a rising prostate-specific antigen (PSA) level with no radio- graphic evidence of cancer [1,2]. Salvage radiation therapy (SRT) to the prostatic fossa is the only treatment option with curative intend for those patients [3]. In a salvage setting a dose of 64– 68 Gy to the prostatic fossa is recommended [4,5]. Several clinical and pathological factors, that have proven to predict the outcome of SRT in multivariate analyses, are used to select patients for this therapy [3]. These factors include PSA pre-SRT level, PSA doubling time, interval to PSA failure, Gleason score, margin status, seminal vesicle invasion, and lymph node metastases. In a recent retro- spective study including 1540 patients Stephenson et al. [5] reported a 6 year progression-free survival rate after SRT of 32%, varying from 48% to 18% in patients with pre-RT PSA level of <0.5 ng/ml and >1.5 ng/ml, respectively, indicating on the one hand that patients with low volume recurrent prostate cancer benefit the most from SRT and on the other hand that there is a sufficient number of patients who do not show a long lasting response after SRT. Local recurrence is the reason for biochemical recurrence in approximately 50% of patients after RP [2]. However, neither a ris- ing PSA level nor its combination with other clinical and pathologic factors give specific information concerning disease location (i.e., local vs. regional vs. distant). Because SRT is only clinically useful in patients with limited (local or regional) disease without distant metastases, tumour spread outside of the prostatic fossa has to be excluded when selecting patients for prostatic fossa SRT. However, conventional imaging modalities currently used for restaging prostate cancer including CT, MRI, and bone scintigraphy, lack the sensitivity for detecting low volume metastatic recurrent disease [6,7]. 111 Indium-Capromab Pendetide (ProstaScint) has been evaluated in several studies in a pre-SRT setting, but its role is not finally defined and its application is still debated [8,9]. There- fore a major challenge for imaging recurrent prostate cancer is to increase diagnostic performance [10]. 0167-8140/$ - see front matter Ó 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.radonc.2011.05.005 ⇑ Corresponding author. Address: Nuklearmedizinische Klinik und Poliklinik der Technischen Universität München, Klinikum rechts der Isar, Ismaninger Straße 22, 81675 München, Germany. E-mail address: msouvatz@yahoo.de (M. Souvatzoglou). Radiotherapy and Oncology 99 (2011) 193–200 Contents lists available at ScienceDirect Radiotherapy and Oncology journal homepage: www.thegreenjournal.com