ESTRO 36 Abstract Book

S716 ESTRO 36 2017 _______________________________________________________________________________________________

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 and preliminary outcome of hypofractionated adjuvant radiotherapy (Hypo-ART) with helical tomotherapy after radical prostatectomy (RP). Material and Methods From February 2014 to July 2016, 30 prostate cancer patients received Hypo-ART for pT2-3 N0-1 and/or R1disease. Median age was 67 years (range 53-74). The surgical Gleason score was: <7 in 8 patients (27%), 7 in 10 (33%) and >7 in 12 (40%). Before RP the median PSA was 7.74 (range: 1.13-44.48) which dropped to 0.025 ng/ml (range: 0 -0.53) before Hypo-ART. RT schedule: all 30 patients received 2.25 Gy in 29 fractions (total dose: 65.25 Gy) to the prostate/seminal vesicle bed; 15 (50%) patients also received 1.8 Gy in 29 fractions to the pelvic lymph nodes (total dose: 52.2 Gy). A simultaneous integrated boost (SIB) technique was used. Hormone therapy (LHRH analogue and/or anti-androgen) was administered to 15 (50%) patients 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. The Mann-Whitney tested compared clinical and dosimetric variables in groups with and without acute toxicity. Results Median follow-up was 26.5 months (range: 3-31). The median duration of HT was 21 months (range 4-33). Only G1-G2 acute genitourinary (GU) and intestinal (GI) toxicities occurred. Acute grade 1 GU toxicity occurred in 14/30 patients (56%), with 13 (43%) developing cystitis and 1 (3%) hematuria. Acute grade 2 GU toxicity (cystitis) developed in 3/30 (10%) patients, with 1 also affected by urinary retension (3%). Acute grade 1 GI toxicity (proctitis) occurred in 14/30 patients (47%), which was associated with rectal bleeding in 2 (7%) and diarrhoea in 5 (17%). Acute grade 2 GI toxicity (proctitis) developed in 3/30 (10%) patients, which was associated with rectal bleeding in 1 (3%) and diarrhoea in 1 (3%). Post Hypo-ART the median PSA was 0.01 ng/ml (range:0-0.22) and the nadir was 0.005 ng/ml (range: 0-0.2). At the last follow-up no patient presented evidence of biochemical or loco- regional recurrence. The probability of developing acute GU on day 44 and GI toxicity on day 43 was 50% (95% CI 41- 46; 95% CI 39-46 respectively ). No differences emerged in clinical and dosimetric variables in group with or without acute toxicity. Conclusion These results suggest that moderate Hypo -ART is safe, effective and well-tolerated. A longer follow-up is needed to assess late toxicity and disease-free survival. EP-1350 Stereotactic re-irradiation for prostate cancer recurrence after upfront surgery and radiotherapy V. Di Cataldo 1 , G. Simontacchi 2 , B. Detti 2 , M. Loi 2 , P. Bonomo 2 , L. Masi 1 , R. Doro 1 , I. Bonucci 1 , S. Cipressi 1 , D. Greto 2 , M. Mangoni 2 , I. Desideri 2 , I. Meattini 2 , S. Scoccianti 2 , E. Olmetto 2 , C. Muntoni 2 , G.A. Carta 2 , L. Livi 2 1 IFCA, Department of Radiotherapy, Firenze, Italy 2 University of Florence, Radiation Therapy Department, Florence, Italy Purpose or Objective Recurrence of prostatic cancer after radical prostatectomy and external-beam radiation therapy Purpose or Objective To evaluate acute toxicity

(EBRT) is a common occurrence in daily clinical practice. We present our experience of re-irradiation with robotic stereotactic body radiation therapy (rSBRT) for isolated recurrence in the prostatic bed from prostate cancer previously treated with surgery and radiation therapy. Material and Methods Between June 2012 and February 2016, rSBRT was administered for isolated local relapse to 22 patients previously treated with prostatectomy and adjuvant (9, 40.1%) or salvage (13, 59.9%) EBRT. After primary treatment, all patients experienced a biochemical recurrence with an isolated relapse in the prostatic bed diagnosed with 18F-choline positron emission tomography– computed tomography (PET) with or without pelvic magnetic resonance (MRI). The gross tumor volume (GTV) was defined on the basis of clinical and radiological findings by image fusion of PET and/or MRI. The total dose was 30 Gy in 5 fractions prescribed to the 80% isodose line. PSA was assessed at 2, 6 and every 3 months, following rSBRT. Toxicity was assessed by the Common Terminology Criteria for Adverse Events toxicity scale (CTCAE v.4.03). Results Twenty-two patients were treated and followed for a median time of 19.5 months (range: 59,4-74.0 months). Prior EBRT had a median total dose of 68 Gy (range 59,4- 74.0 Gy ) in 1,8-2 Gy for fraction. Median time from EBRT to relapse was 73,3 months (range: 16,9-203.1). Seven patients were receiving androgen deprivation therapy (ADT) following prior biochemical failure; median pre-re- irradiation PSA value was 1.9 ng/ml (0,4-30). Eighteen patients had biochemical response at 2 and 6 months, with a median PSA decrease of 44,9% and 64,9% respectively; four patients experienced early PSA progression at 2 and 6 months, the median PSA rise was 85,1% and 228,6% respectively. At the time of our analysis, 10 patients showed no evidence of disease, in 2 patients an hormonal treatment was continued with stable PSA levels, while 10 patients had biochemical relapse and four of these had metastatic disease. Biological Progression-free Survival (bPFS) was 81.8% and 68.2% at 6 and 12 months, respectively. Treatment was well tolerated, genitourinary acute and late G1-G2 toxicity occurred in 6 and 5 patients respectively, while two patients experienced late rectal G1-G2 toxicity. At univariate and multivariate analysis of pre-treatment variables, impaired biochemical relapse- free survival (BRFS) was correlated with the use of ADT at the moment of the treatment (p=0.013). Subset analysis in responding patients did not found predictor of BRFS. Conclusion RSBRT for isolated recurrence in the prostatic bed from prostate cancer previously treated with prostatectomy and EBRT showed favourable results in biochemical control with low and acceptable toxicity, however further prospective studies are needed to confirm these results. EP-1351 Stereotactic radiotherapy in recurrent prostate cancer previously treated by radical irradiation M. Loi 1 , B. Detti 2 , G. Simontacchi 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 , M. Perna 2 , V. Carfora 2 , G. Francolini 2 , I. Meattini 2 , M. Mangoni 2 , S. Scoccianti 2 , L. Livi 2 1 Azienda Ospedaliera Universitaria Careggi, Radiotherapy Unit, Firenze, Italy 2 Universita degli Studi di Firenze, Radiotherapy Department, Florence, Italy 3 IFCA, Radiotherapy Department, Florence, Italy Purpose or Objective Biochemical recurrence can occur following definitive external beam radiation therapy (EBRT) for localized prostate cancer. Focal robotic stereotactic body radiotherapy (rSBRT) to the recurrent intraprostatic tumor is emerging as a valuable option in this setting. In this retrospective study we evaluated efficacy and toxicity of