Stereotactic reirradiation for locally recurrent prostate cancer after definitive radiotherapy
PD-0576
Abstract
Stereotactic reirradiation for locally recurrent prostate cancer after definitive radiotherapy
Authors: Giulio Francolini1, Cecilia Cerbai2, Maria Grazia Carnevale2, Vanessa Di Cataldo1, Beatrice Detti1, Mauro Loi1, Giulio Frosini1, Barbara Guerrieri2, Ilaria Morelli2, Manuele Roghi2, Michele Ganovelli2, Andrea Allegra2, Viola Salvestrini3, Luca Visani3, Emanuela Olmetto1, Daniela Greto1, Gabriele Simontacchi1, Monica Mangoni2, Isacco Desideri2, Icro Meattini2, Lorenzo Livi2
1University of Florence, Radiation Oncology Unit, Azienda Ospedaliero Universitaria Careggi, Florence, Italy; 2University of Florence, Department of Experimental and Clinical Biomedical Sciences "M. Serio", Florence, Italy; 3Istituto Fiorentino di Cura e Assistenza (IFCA), Cyberknife Center, Florence, Italy
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Purpose or Objective
Treatment of locally recurrent prostate cancer (pCa) after definitive radiotherapy (RT) is a matter of debate. Treatment alternatives in this scenario (e.g Salvage Prostatectomy or palliative androgen deprivation therapy, ADT) are burdened by a significant risk of toxicity. Stereotactic re-irradiation (re-SBRT) is an emerging approach potentially allowing a non-invasive local therapy. However, data confirming efficacy and tolerability are currently needed to support this technique in current clinical practice. Here we present a mono-centric cohort reporting long term clinical outcomes and safety after Cyberknife robotic re-SBRT for local recurrence after primary RT.
Material and Methods
Data about 57 patients consecutively treated from June 2012 to February 2021 were collected and analyzed. All patients underwent previous definitive radiotherapy for non-metastatic pCa and were affected by biochemical relapse defined according to European Urology Association criteria. Macroscopic evidence of intra-prostatic recurrence was detected in all patients through 18F-choline PET/CT and Magnetic Resonance Imaging. Patients with metastatic or regional nodal disease were excluded. All patients underwent CyberKnife robotic reSBRT for a total dose of 30 Gy in 5 fractions every other day. During follow up, PSA was assessed at every 3 months following re-irradiation. Gastrointestinal (GI) and Genitourinary (GU) Toxicity was assessed at each scheduled visit by the Common Terminology Criteria for Adverse Events toxicity scale (CTCAE v.4.03).
Results
After a median follow up of 58.8 months (IQR 48.9-79), Biochemical Relapse (BR) was detected in 27 (47%) patients, for a median Median BR-free survival (BRFS) of 52.8 months (95% C.I. 36.4- 58.3). Metastases occurred in 15 pts (26%), median metastasis free survival (MFS) was not reached. 15 (26%) patients died, for a median OS of 83.2 months (95% C.I 79.3-83.2). At univariate analysis, PSA >2.5 ng/ml was significantly associated to worse BRFS (51.2 vs 30 months, p=0.03) and MFS (55.2 vs 41.3 months, p=0.04). Concurrent ADT was associated with worse MFS (55 vs 35.6 months, p=0.04). However, none of these factors persisted as an independent predictor of outcome at Cox multivariate analysis. G1, G2 and G3 late GI toxicity were recorded in 3, 2 and 1 pts respectively, while 11 and 8 patients developed G1 and G2 late GU toxicity. No late G3 GU adverse events were recorded.
Conclusion
Re-SBRT confirmed to be a safe and viable treatment option for local recurrence after definitive radiotherapy with 5 years of median follow-up. Prospective data are awaited to develop correct selection criteria and guide current clinical practice.