ESTRO 36 Abstract Book

S715 ESTRO 36 2017 _______________________________________________________________________________________________

After a median follow-up (FU) after ENRT of 44 mo (range, 2-133), 27 pts (51%) showed PSA progression, with a 5-yr biochemical disease free-survival of 43±8.3%. The 5-yr distant progression-free survival (DPFS) rate was 58.2±8.5% (n=19 pts with clinical progression). Pts with a PSA DT at relapse <3 mo showed a worse 5-yr DPFS compared to pts with a PSA DT ≥ 3mo (36.8% vs. 63.6%, p=0.029), while a trend towards significance was observed for pts with 1 vs ≥ 2 recurrent nodes (71.8% vs. 44.9%, p=0.089). Overall survival rate at 5-yr was 86.4±6.9% (2 over 4 pts died from PCa). Ten of 19 clinically relapsing pts presented a new oligometastatic progression (7 nodal/2 bone/1 combined). One patient presented a local relapse in the previously untreated prostate bed. Eight out 10 pts were treated with a new RT course, with 3 pts in complete remission at last FU. Only 2 pts presented with a CTCAE v3.0 Grade ≥2 genitourinary toxicity. Conclusion ENRT combined with concomitant short-course AD is a safe and effective salvage modality for patients with oligorecurrent nodal PCa, able to better delay distant progression compared to historical series using focal SBRT. Prospective randomized studies comparing focal SBRT vs ENRT are warranted to define the best treatment strategy for oligorecurrent nodal PCa. EP-1347 Treatment outcomes with hypofractionated high-dose radiation therapy for prostate cancer D. Candini 1 , F. López Campos 1 , C. Vallejo Ocaña 1 , M. Martín Martín 1 , A. Hervás Morón 1 1 Hospital Ramon y Cajal, Radiation Oncology, Madrid, Spain Purpose or Objective To report treatment results, genitourinary (GU) and lower gastro-intestinal (GI) toxicity of a retrospective cohort of prostate cancer patients treated with hypofractionated radiotherapy (hypo-RT) with a high equivalent biological From April 2014 to October 2015, 35 patients with histologically confirmed intermediate risk prostate cancer defined by National Comprehensive Cancer Network (NCCN) risk group were assigned to receive hypo-RT with a total dose of 63,4 Gy/20 fractions. Use of image-guided techniques (IGRT) with fiducial markers was required. All patients were given radiotherapy with 6 months of neoadjuvant and concurrent androgen suppression. GI and GU toxicity were prospectively evaluated according to modified RTOG criteria. Toxicity was considered “acute” if occurred during and/or within 3 months after the treatment and “sub-acute” if occurred between 3 and 12 months after the treatment. Biochemical recurrence was defined as a PSA concentration superior than nadir plus 2 35 patients with a median age of 76 years (range 61-86 years) were treated in the defined period receiving hypo- RT. The median follow-up was 20.3 months (range 12 – 30 months). Acute GU toxicity grade I occurred in 20 patients (57.1%), grade II in 2 patients (5.7%). Acute GI toxicity grade I were observed in 6 patients (17.1%), grade II in 3 patients (8.6%). None developed acute GU or GI toxicity grade III or IV. Sub-acute GU toxicity occurred as follows: grade I in 9 patients (25.7%) and grade II in 1 patients (2.9%). Sub- acute GI toxicity grade I was observed in 6 patients (17.1%) and grade II in 3 patients (8.6%). No late grade III-IV GU or GI toxicity was detected. For one patient a TURP was planned at 8 months after treatment, for urethral stricture. Only 1 patient (3%) developed biochemical recurrence after a follow-up of 27 months. Conclusion effective dose (BED). Material and Methods ng/mL. Results

Hypo-RT (63,4 Gy/20 fractions) with a high equivalent BED (EQD2Gy_tumor = 85 Gy) produces aceptable acute and sub-acute toxicity rates with excellent outcomes of biochemical control for intermediate risk prostate cancer. Longer term follow-up should be analyzed to confirm these data. EP-1348 Set-up errors in prostate cancer radiotherapy based on cone-beam computed tomography. M. Trignani 1 , G. Caponigro 1 , M. Di Biase 1 , P. Bagalà 1 , M.D. Falco 1 , A. Vinciguerra 1 , A. Augurio 1 , M. Di Tommaso 1 , L. Caravatta 1 , D. Genovesi 1 1 Ospedale Clinicizzato S.S. Annunziata, Radiotherapy, Chieti, Italy Purpose or Objective To evaluate set-up accuracy using cone-beam computed tomography (CBCT) in patients with prostate cancer receiving VMAT (volumetric modulated arc therapy) or IMRT (intensity modulated radiation therapy) techniques. Material and Methods From January 2015 to September 2016, 1199 CBCT referred to 98 prostate cancer patients received radiation treatment at our Institution using Elekta Synergy Agility Linear Accelerator were acquired, recorded and evaluated. All patients underwent to planning computed tomography (CT) in supine position; knees and ankles were placed in a steady and comfortable position using a footrest. CT scans with slices at 5 mm were acquired at 2 mm in condition of fully bladder (0.75 liter of water, 45 minutes prior to CT scan) and empty rectum. Planning CT was sent to Oncentra Master Plan planning system and then via DICOM to XVI software for co-registration with the CBCT scans. For the CBCT acquisition we used the “pelvis M15”; the Grey level algorithm was employed to obtain 3D-3D co- registration with CT planning. An internal protocol was adopted to reduce interfraction set-up errors and to correct systematic errors. This protocol consisted in the execution of 5 consecutively CBCT during first week of treatment and once weekly CBCT during RT course. On the basis of literature data an on-line correction protocol was adopted: the tolerance level was 3 mm for translation displacements and 3° for rotations; translation displacements were applied in case of values >3 mm, while for rotation >3° patients were repositioned. Then an offline correction was applied with the mean of first 5 scans used to correct systematic errors with 3 mm. Means (m) and standard deviations (SD) of all translational (x, y, z) and rotational displacements were calculated in relation to the first 5 and the following CBCTs. The Wilxocon test was used to evaluate statistically significant differences between displacements related to first 5 CBCTs and to the following CBCTs. Results Results are summarized in Table 1. Median values were <3 mm for all CBCTs, for both the first five and following CBCTs, mean values were within 5mm. Greater shifts were observed on z axis. Wilcoxon test showed a statistically significant correlation only for the x (p value = 0.001). Conclusion In our study, we have analyzed translational set-up uncertainties in prostate cancer treatments using CBCT and we found that all the displacements were within 5 mm, well within the offset established. The action level of 3 mm currently adopted at our center results safe and it constitutes a good start point to reduce margin CTV- PTV. EP-1349 Adjuvant 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 , M. Mendichi 1 , M. Tenti 1 , F. Tamburi 2 , V. Bini 4 , C. Aristei 3 1 University of Perugia, Radiation Oncology Section,