ESTRO 36 Abstract Book

S717 ESTRO 36 2017 _______________________________________________________________________________________________

Material and Methods Twenty-three prostate cancer patients with 27 isolated nodal recurrence were treated by single fraction rSBRT between April 2012 and March 2016. Lymphnodal disease was assessed by 18 F-choline positron emission tomography– computed tomography ( 18 F-chol-PET); all patients received single fraction rSBRT. PSA was assessed at 3 months and every 3 months following treatment. Toxicity was assessed by the Common Terminology Criteria for Adverse Events toxicity scale (CTCAE v.4.03). Results Median patient age at rSBRT was 75 (54-85) years. All patients underwent definitive RT (2, 8.7%) or surgery (21, 91.3%) as primary treatment to the prostate; among operated patients, RT was administered as an adjuvant or salvage treatment in 3 (13.0%) and 3 (13.0%) patients respectively. Median time from primary treatment to relapse was 69.5 (7.6-205.4) months; median pre- treatment PSA value was 2.13 ng/ml (0,35-19.9). Five patients (21.7%) were receiving endocrine therapy (ET) for at least 6 months following prior biochemical failure (BF). Nodal sites of disease were pelvic and lumboaortic nodes in 22 (81.4%) and 5 (18.6%) cases, respectively;four patients were simultaneously treated on a synchronous nodal relapse. Median dose was 24 (20-24) Gy. At 3 months, 12 (52.2%) patients showed biochemical response (median decline -64.6%, 0.8-97.8); 11 (47.8%) patients experienced early PSA progression (median elevation +30.8%, 2.9-390.9). At the time of our analysis, after a median follow-up of 13.6 months (6.0-47.8), 8 patients showed no evidence of disease, 2 patients were continuing ET with stable PSA levels, while 13 patients experienced biochemical progression: among them, 7 patients started ET for 18 F-chol-PET-negative disease, 2 patients had nodal relapse on non-irradiated site and 4 patients developed distant metastasis. At statistical analysis, median time to BF was 10.0 months. Overall Biochemical Relapse-Free Survival (bPFS) was 56.5% at 6 months and 47.8% at 12 months; no predictive factor was related to bPFS. Subset analysis in responding patients showed a median time to BF of 14.7 months; PSA level >4.0 ng/ml showed a borderline predictive value for BF (p=0.054). Grade1 bladder toxicity was reported in one case. Conclusion Isolated nodal relapse of prostate cancer can be safely treated by single fraction rSBRT with excellent tolerance and promising biochemical control; careful selection of patients is mandatory to avoid unnecessary treatment of patient with undetectable advanced disease. EP-1353 Salvage hypofractionated radiotherapy for prostate cancer: acute toxicity S. Saldi 1 , R. Bellavita 2 , I. Palumbo 3 , C. Mariucci 1 , E. Arena 1 , M. Lupattelli 2 , A. Podlesko 1 , S. Russo 2 , R. Dottorini 2 , V. Bini 4 , C. Aristei 3 1 University of Perugia, Radiation Oncology Section, Perugia, Italy 2 Perugia General Hospital, Radiation Oncology Section, Perugia, Italy 3 University of Perugia and Perugia General Hospital, Radiation Oncology Section, Perugia, Italy 4 Perugia General Hospital, Internal Medicine Endocrin and Metabolic Sciences Section, Perugia, Italy Purpose or Objective To evaluate acute toxicity and the preliminary outcome of hypofractionated salvage radiotherapy (Hypo-SRT) with helical tomotherapy after radical prostatectomy (RP). Material and Methods From March 2013 to July 2016, 58 patients underwent Hypo-SRT for biochemical (BR) or local recurrence (LR) after radical prostatectomy (PR). Median age was 67 years (range 52-84). The surgical Gleason score was : <7 in 24 patients (41%), 7 in 22 (38%), >7 in 12 (21%); median PSA pre-SRT was 0.258 ng/ml (range: 0.2-8.65). RT

robotic SBRT for exclusive local failure after primary EBRT. Material and Methods Data from 28 patients treated at our Institution from September 2012 to December 2015 with rSBRT for prostate cancer recurrence after definitive EBRT were retrospectively reviewed. Local intraprostatic recurrence was assessed by 18 F-choline positron emission tomography– computed tomography (PET); a dose of 30 Gy was delivered in 5 fractions. PSA was assessed at 2 months, 6 months, and every 3 months following rSBRT. Toxicity was assessed by the Common Terminology Criteria for Adverse Events toxicity scale (CTCAE v.4.03). Results Patients were stratified in low (5, 17.9%), intermediate (9, 32.1%) and high risk group (14, 50.0 %) at diagnosis. Median patient age at rSBRT was 78.5 (62-86) years. All patients received prior EBRT for a median total dose of 76 Gy (62- 80 Gy) in 2 (1.8-3.1) Gy/fraction. Median time from primary treatment to relapse was 74.1 (19.3-149.2) months. Five patients were receiving androgen deprivation (AD) following prior biochemical failure; median pre-treatment PSA value was 2.7 (2.1-14.4) ng/ml. Twenty-five patients showed biochemical response to treatment at 2 and 6 months, median PSA decline -54.0% (2.2-95.0) and -76.0% (35.9-95.0%) respectively; three patients experienced early PSA progression at 2 and 6 months, median PSA elevation +112.3% (20.0-204.5%) and +267.0% (41.9-309.1%), respectively. At the time of our analysis, after a median follow-up of 20.9 (6.3-49.2) months, 10 patients showed no evidence of disease, 2 patients pursued AD with stable PSA levels, while 10 patients experienced biochemical relapse; among them, metastatic recurrence occurred in 4 cases. Biochemical Progression-Free Survival (bPFS) was 96.4% and 75.0% at 12 and 18 months, respectively. Rectal and bladder acute toxicity grade 1-2 was found in 4 and 1 cases, respectively ; grade 1-2 late rectal and bladder toxicity occurred in 1 and 7 cases, respectively. One patient experienced both grade 3 acute and chronic bladder toxicity, consisting of acute urinary retention and hematuria respectively. At univariate and multivariate analysis of pre-treatment variables, impaired bPFS was correlated only with high risk category at diagnosis (HR:13.06, p=0.021). No predictive factor for improved bPFS was found at subset analysis in responding patients, though a trend was observed for PSA decline at 6 months >76.0% (p=0.06). Conclusion Focal rSBRT can achieve long-lasting remission and delay initiation of medical treatment,in particular in low/intermediate risk patients at diagnosis, with acceptable incidence of acute and late toxicity. EP-1352 Single-fraction stereotactic body radiotherapy for nodal oligorecurrent prostate cancer M. Loi 1 , G. Simontacchi 2 , B. Detti 2 , V. Di Cataldo 3 , P. Bonomo 2 , L. Masi 3 , R. Doro 3 , I. Bonucci 3 , S. Cipressi 3 , I. Desideri 2 , D. Greto 2 , C. Becherini 2 , C. Delli Paoli 2 , R. Grassi 2 , M. Lo Russo 2 , I. Meattini 2 , S. Scoccianti 2 , M. Mangoni 2 , L. Livi 2 1 Azienda Ospedaliera Universitaria Careggi, Radiotherapy Unit, Firenze, Italy 2 University of Florence, Radiotherapy Department, Florence, Italy 3 IFCA, Radiotherapy Department, Florence, Italy Purpose or Objective Advances in metabolic imaging allows the detection of oligorecurrent nodal disease in prostate cancer patients after primary surgical or radiation treatment (RT): focal nodal stereotactic RT could be proposed in order to treat the site of recurrence. The aim of the study is to evaluate efficacy and toxicity of single fraction robotic stereotactic radiation therapy (rSBRT) for isolated nodal failure in prostate cancer patients