ESTRO 36 Abstract Book

S725 ESTRO 36 _______________________________________________________________________________________________

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 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 schedule: 24/58 (41%) patients with BR received 2.25 Gy in 32 fractions (Total dose:72 Gy); 34/58 (59%) patients with LR received 2.1 Gy in 33 fractions (Total dose: 69.3 Gy) to the prostate/seminal vesicle bed and 2.25 Gy in 33 fractions to the LR site (total dose:74.25 Gy) using a simultaneous integrated boost (SIB) technique; 6/58 (10%) patients received 1.6 Gy to the pelvic lymph nodes (total dose 52.8 Gy), using a SIB technique. Hormone therapy ( HT-LHRH analogue and/or anti-androgen) was administered to 17 patients (29%) with high risk features. Toxicity was graded according to the Common Terminology Criteria for Adverse Events version v4.0. Biochemical failure was defined by ASTRO criteria. The Kaplan-Meier method determined time-to-acute toxicity events and the Mann-Whitney test compared clinical and dosimetric variables in groups with and without acute toxicity. Results The median follow-up was 12 months (range:3-41).The median duration of HT was 85 months (range 2-168). Only G1-G2 acute genitourinary (GU) and intestinal (GI) toxicities occurred. Acute grade 1 GU toxicity occurred in 28 patients (48%), with 25 (43%) developing cystitis and 3 (5%) hematuria. Acute grade 2 GU toxicity (cystitis) developed in 6/58 (10%) patients, with 1 also affected by urinary retension (2%). Acute grade 1 GI toxicity (proctitis) occurred in 25/58 patients (43%), which was associated with rectal bleeding in 2 (3%). Acute grade 2 GI toxicity (proctitis) developed in 4/58 (7%) patients, which was associated with rectal bleeding in 1 (2%). Post Hypo-ART the median PSA was 0.1 ng/ml (range:0-7.01) and the nadir was 0.03 ng/ml (range: 0-5.67). Biochemical recurrence and /or loco-regional relapse occurred in 10/58 (17%) patients at a median of 19 months after treatment (range: 10-40). Statistical analysis: after Hypo- ART there was 50% probability of developing acute GU toxicity on day 52 and GI toxicity on day 43. Dmax to the prostate/seminal vesicle bed was greater in patients who developed acute GI toxicity. Conclusion Low grade acute GU and GI toxicity and early biochemical response demonstrated that moderate Hypo-SRT was safe and effective. A longer follow-up is required to confirm these outcomes. EP-1354 Delayed Salvage Radiotherapy for Macroscopic Local Recurrence after Radical Prostatectomy M. Shelan 1 , S. Odermatt 1 , B. Bojaxhiu 1 , O. Elicin 1 , D.M. Aebersold 1 , A. Dal Pra 1 1 Bern University Hospital, Radiation Oncology, Bern, Switzerland