ESTRO 38 Abstract book

S852 ESTRO 38

All patients underwent treatment with IMRT up to a total dose of 62.5Gy/2.5Gy/day in 25 fractions (EQD2Gy for a/b=1.5 of 70 Gy). Daily verification was performed with IGRT. Eight p (10%) received androgen deprivation. Acute Toxicity was assessed according to CTCAE 5.0. Late toxicity was scored with RTOG/EORTC criteria. Biochemical relapse was defined as PSA increase of 0,2 ng/mL or greater from the post-RT nadir (confirmed with a second increase). Institution rewiew board approved this study

gastrointestinal (GI) scale according to the RTOG criteria (Grade 0-5). The PSA was systematically registered. Results We analyzed 205 patients with follow-up longer than 6 months The average age was 69 years [48-86.6]. The distribution by risk group was: 12.6%, 62.2%, 23.3% and 1.9% for low, medium, high and metastatic respectively. Average follow-up: 24.7 months [5.7-46.3] The mean of the IPSS prior to SBRT was = 6.1 [0-35]. After SBRT: 5.1 [0- 31], 5.5 [0-30], 4.7 [0-22], 4.7 [0-19] and 5.5 [0-26] to 6, 12, 18, 30 and 42 months respectively . The rate and degree of rectal toxicity at the end of SBRT was: G0 = 96.6%; G1 = 2.4% and G2 = 1%. At 6 months: G0 = 84.2%; G1 = 9.2%, G2 = 5.1% and G3 = 1.5%. At 12 months: G0 = 89.3%; G1 = 5.3%; G2 = 2.4%, G3 = 1.8% and Gr4 = 1.2%. At 18 months: G0 = 90.8%; G1 = 6.8%; G2 = 0.8% and G4 = 0.8%. At 30 months: G0 = 90.7%, Gr1 = 8.5 and G4 = 0.8%. At 42 months: G0 = 99.2%, Gr4 = 0.8% The mean PSA value in ng / ml, Pre-SBRT was = 16.54 [0.01-1890] and after 24 months = 5.32 [0.03-115] Conclusion According to the presented results we can suggest that SBRT Prostate based on a Novalis platform with IGRT ExacTrac based, is convenient for the patient, has acceptable toxicity rate, without significant differnce with the Cone-Beam results published. The assessment of the impact on disease control deserves longer follow-up. EP-1578 Hypofractionated postoperative imrt-igrt in prostate cancer single-institution preliminary results J. Valero Albarran 1 , E. Pérez Sanchez 2 , A. Montero 1 , O. Hernando Requejo 3 , E. Sanchez 1 , R. Ciervide 1 , M. Lopez 1 , M.D.L.O. Garcia Aranda 3 , X. Chen 1 , B. Alvarez 4 , A. Acosta 1 , R. Alonso 5 , J. Palma 1 , M. Nuñez Baez 4 , P. Fernandez Leton 6 , J. Martin Asenjo 7 , J.M. Perez 8 , J. Garcia 8 , D. Zucca 9 , M. De la Casa 9 , M. Serrano 10 , L. Osorio 11 , C. Escaleras 11 , M.D. Fenor 12 , C. Rubio 13 1 Hospital University HM Sanchinarro, Radiation Oncology, Madrid, Spain ; 2 Hospital University Nuestra Señora de la Candelaria, Radiation Oncology, Tenerife, Spain ; 3 Hospital University HM Sanchinarro, Radiation Oncology- , Madrid, Spain ; 4 Hospital University HM Sanchinarro-, Radiation Oncology, Madrid, Spain ; 5 Hospital University HM Puerta del Sur, Radiation Oncology, Madrid, Spain ; 6 Hospital University HM Sanchinarro, Hospital University HM Sanchinarro- Radiophisyc, Madrid, Spain ; 7 Hospital University HM Sanchinarro, Radiophisyc, Madrid-, Spain ; 8 Hospital University HM Sanchinarro, Radiophisic, Madrid, Spain ; 9 Hospital University HM Sanchinarro-, Radiophisic, Madrid, Spain ; 10 Hospital University HM Sanchinarro, UrologyUrology, Madrid, Spain ; 11 Hospital University HM Sanchinarro, Urology, Madrid, Spain ; 12 Hospital University HM Sanchinarro, Medical Oncology, Madrid, Spain ; 13 Hospital University HM Sanchinarro, Radiation Oncology, Spain, Spain Purpose or Objective This report describe our experience about feasibility and preliminary results of a moderate hypofractionated intensity modulated radiotherapy (Hypo-IMRT) schedule for prostate cancer (PC) after radical prostatectomy Material and Methods From October 2015-June 2018, 80 patients (p) (median age, 62y range 45-75y) were included for adjuvant (31%) or salvage radiation therapy (69%). NCCN risk criteria: low (n=32%), intermediate (n=38%) and high (n =30 %); pre- treatment PSA: median 9.34 ng/ml (range 3.40 - 30ng/ml). Forty-two per cent of the patients (34 p) have previous urinary incontinence (33 p G1-2; 1 p G3) . Pathological characteristics are summarized in Table 1. In 80% of the patients, two internal gold-fiducial markers were placed transperineally guided by transrectal ultrasound before treatment. CTV was contoured according to RTOG guidelines including prostate bed and expanded 3 mm posteriorly and 5 mm in all other direction to create PTV.

Results All patients received complete treatment. There were no complications during marker placement. Follow-up: 17 months (range 3-39 months). Of the 80 patients, 68 demonstrated a continuous biochemical response after treatment. Three patients had regional lymph nodes and 3 p distant metastasis. Only one patient died for lung cancer. All remaining patients were alive at the last follow up visit. The cancer specific survival is 100%. The estimated actuarial SLRB rate at 1, 2 and 3 years was 88%, 78% and 72% respectively. A pre salvage PSA level no significant prognostico factor for biochemical control (Breslow p = 0.075), log-rank (p=0.251).Maximal acute urinary (GU) toxicity: G2 in 4% (3 p) of patients. Maximal acute gastrointestinal (GI) toxicity: G2 in 1% of patients (1p). There was no grade 3, 4 or 5 acute toxicity. Neither urinary stress nor incontinence was influenced by radiation therapy. Late toxicities were evaluated in all patients. No G3 or greater late toxicities were observed. Late G2-GU: 2%; G2-GI: 0. No relationship was found between acute and late GU or GI adverse effects and any of the analyzed parameter> age, androgen deprivation or urinary incontinence pre/treatment. Conclusion Hypo-IMRT with IGRT for postoperative PC is feasible and well tolerated showing encouraging rates of BRFS although longer follow up is required. EP-1579 Prior prostatectomy MRI improves target coverage of adjuvant radiotherapy for pT3bNo prostate cancer G. Kacso 1 , T. Popescu 2 , P. DAniel 2 , C. Iacob 3 , R. Zahu 3 , A. Eva 4 , D. Dordai 4