Dose-intensified Versus Conventional-dose Salvage Radiotherapy for Biochemically Recurrent Prostate Cancer After Prostatectomy: The SAKK 09/10 Randomized Phase 3 Trial.

Salvage radiotherapy (SRT) is utilized for biochemical progression of prostate cancer after radical prostatectomy (RP).

To report the outcomes of the SAKK 09/10 trial comparing conventional and dose-intensified SRT.

SAKK 09/10 was a randomized, multicenter, phase 3 trial that recruited men with biochemical progression after RP.

Patients were randomly assigned to conventional-dose (64 Gy) or dose-intensified SRT (70 Gy) to the prostate bed without hormonal therapy.

The primary endpoint was freedom from biochemical progression (FFBP). Secondary endpoints included clinical progression-free survival (PFS), time to hormonal treatment, overall survival (OS), acute and late toxicity (Common Terminology Criteria for Adverse Events v4.0), and quality of life (QoL).

Between February 2011 and April 2014, 350 patients were randomly assigned to 64 Gy (n = 175) or 70 Gy (n = 175). Median prostate-specific antigen at randomization was 0.3 ng/ml. After median follow-up of 6.2 yr, the median FFBP was 8.2 yr in the 64 Gy arm and 7.6 in the 70 Gy arm (log-rank p = 0.4), with a hazard ratio of 1.14 (95% confidence interval 0.82-1.60). The 6-year FFBP rates were 62% and 61%, respectively. No significant differences in clinical PFS, time to hormonal treatment, or OS were observed. Late grade 2 and 3 genitourinary toxicity was observed in 35 (21%) and 13 (7.9%) patients in the 64 Gy arm, and 46 (26%) and seven (4%) in the 70 Gy arm, respectively (p = 0.8). Late grade 2 and 3 gastrointestinal toxicity was observed in 12 (7.3%) and seven patients (4.2%) in the 64 Gy arm, and 35 (20%) and four (2.3%) in the 70 Gy arm, respectively (p = 0.009). There were no significant differences in QoL.

Conventional-dose SRT to the prostate bed is sufficient in patients with early biochemical progression of prostate cancer after RP.

The optimal radiation therapy dose for patients who have increased tumor markers after surgery for prostate cancer is unclear. We found that administering a higher dose only increased the gastrointestinal side effects without providing any benefits to the patient. This clinical trial is registered on ClinicalTrials.gov as NCT01272050.

European urology. 2021 Jun 14 [Epub]

Pirus Ghadjar, Stefanie Hayoz, Jürg Bernhard, Daniel R Zwahlen, Tobias Hölscher, Philipp Gut, Bülent Polat, Guido Hildebrandt, Arndt-Christian Müller, Ludwig Plasswilm, Alexandros Papachristofilou, Corinne Schär, Marcin Sumila, Kathrin Zaugg, Matthias Guckenberger, Piet Ost, Christiane Reuter, Davide G Bosetti, Kaouthar Khanfir, Silvia Gomez, Peter Wust, George N Thalmann, Daniel M Aebersold, Swiss Group for Clinical Cancer Research (SAKK)

Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Switzerland. Electronic address: ., SAKK Coordinating Center, Bern, Switzerland., IBCSG Coordinating Center, Bern, Switzerland; Department of Medical Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland., Department of Radiation Oncology, Kantonsspital Graubünden, Chur, Switzerland., Department of Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany., Department of Radiation Oncology, Kantonsspital Luzern, Luzern, Switzerland., Department of Radiation Oncology, University Hospital Würzburg, Würzburg, Germany., Department of Radiation Oncology, University Hospital Rostock, Rostock, Germany., Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany., Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Switzerland; Department of Radiation Oncology, Kantonsspital St. Gallen, St. Gallen, Switzerland., Department of Radiation Oncology, University Hospital Basel, Basel, Switzerland., Department of Radiation Oncology, Hirslanden Hospital Group, Zürich, Switzerland., Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Switzerland; Department of Radiation Oncology, Stadtspital Triemli, Zürich, Switzerland., Department of Radiation Oncology, University Hospital Zürich, Zürich, Switzerland., Department of Radiation Oncology, Ghent University Hospital, Ghent, Belgium., Department of Radiation Oncology, Kantonsspital Münsterlingen, Switzerland., Department of Radiation Oncology, Istituto Oncologico della Svizzera Italiana, Bellinzona, Switzerland., Department of Radiation Oncology, Hôpital Valais, Sion, Switzerland., Department of Radiation Oncology, Kantonsspital Aarau, Aarau, Switzerland., Department of Radiation Oncology, Charité Universitätsmedizin Berlin, Berlin, Germany., Department of Urology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland., Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Switzerland.