Abstract Book

S832

ESTRO 37

positive paraaortic lymphatic nodes were treated by stereotactic radiotherapy 5 Gy per fraction to 20 Gy. Results Eight patients were treated following for the above- mentioned method. Median follow up was 18 (3-36) months. Nobody had grade 2 acute gastrointestinal toxicity. Local control rate was 100%. Biochemical response rate after radiation therapy was 87,5% (7/8). Conclusion We would like to suggest a new method of radiotherapy for patients with paraaortic lymph nodes metastases of prostate cancer after definitive and salvage radiation therapy which consists of two principles: the one is to prophylactic irradiate paraaortic lymph nodes and the second one is to escalade dose to PET-positive lymph nodes. The result shows that the above-mentioned method is a well-tolerated approach with good rate of biochemical control. EP-1541 Prostate cancer: moderate hypofrationated in post-operative setting F. Tramacere 1 , M. Portaluri 1 1 Radioterapia Ospedale Antonio Perrino, ASL Brindisi, Brindisi, Italy Purpose or Objective Few data are available about hypofractionated in post- prostatectomy. The aim of the study was to investigate retrospectively outcome, acute and late complications in prostate cancer treated with postoperative and salvage intent using moderate hypofractionated 3D conformal 69 Consecutive patients (pts) were treated. The mean age was 66 years, median 69 (range 51-77). According to 2.2017 NCCN prognostic classification 29% ps was intermediate risk, 42% high risk, 23% very high risk, and 4% metastatic (N+). The pts were treated with total dose 62.5 Gy in 2.5 Gy/fr (25 fr) on prostatic fossa and one pts with 62 Gy 3 Gy/fr; 5 fr/weeks with LINAC 6-15 MV, 7 fields. The mean PSA at the diagnosis was 18.7 ng/ml; median 10.4 (range 0.59-188). Surgical pathological specimens showed pT2 31% (R1 81%), pT3a 41% (R1 57%, Close 7%), pT3b 26% (R1 72%). Hormonotherapy was administrated in 20%. All the pts were clinically evaluated for urinary and rectal late complications according to CTC.AE 4.0 and RTOG/EORTC scale. Results After median follow-up of 55 months (mo) range 38-76 mo the 68% of pts were No Evidence of Disease (NED), 27% Alive With Disease (AWD); 2 pts Died Other Cause (DOC) and one pts Died Of Disease (DOD). 66% of pts AWD had positive or close margins. The median PSA at last follow-up was 0.08. 3 pts were affected by Alzheimer's disease and 3 developed a second malignant neoplasm (colon, lung and pancreatic cancer). Biochemical recurrence was more common in pts with higher-very higher NCCN grade (71%) and N+ (100%), respect intermediate grade (22%). The mean of mo between surgery and the start of RT was 10, median 5, (range 2-121). Acute toxicity: No Ps developed with grade 3 or 4 acute gastrointestinal (GI) or genitourinary (GU) toxicity. G2 GI was 4.3% (proctitis). Only one Ps G2 GU. Late toxicity: ≥ G2 GI was reported in 4.5% and ≥ G2 GU in 12%, of these one pts had a rectal-bladder fistula and 3/66 (4.5%) urethral strictures. (Other result show in Table). radiotherapy (Hypo). Material and Methods

Pre-RT urinary incontinence was noted in 28/67 Ps (42%), while in post-RT with grade G1, G2 and G3 severity noted in 34%, 17% and 4,5% respectively. Conclusion Moderate hypofractionated regimen appears a feasible option with similar toxicity to SF. Hypo is well tolerated also with 3D conformal radiotherapy. We found good biochemical control despite the high risk factors. Moderate hypofractionation can become the standard of care. Wait for to further prospective data to validate these results. EP-1542 SBRT for oligometastatic lymph nodes in hormone-sensitive and castration-resistant prostate cancer. N. Giaj-Levra 1 , S. Fersino 1 , A. Fiorentino 1 , U. Tebano 1 , D. Aiello 1 , R. Mazzola 1 , F. Ricchetti 1 , R. Ruggieri 1 , M. Salgarello 2 , F. Alongi 1,3 1 Sacro Cuore Don Calabria, Radiation Oncology, Negrar, Italy 2 Sacro Cuore Don Calabria, Nuclear Medicine Department, Negrar, Italy 3 University of Brescia, Radiation Oncology, Brescia, Italy Purpose or Objective To evaluate the feasibility and the early side effects of Stereotactic Body Radiotherapy (SBRT) for oligometastatic lymph nodes in hormone-sensitive and castration resistant prostate cancer (PC) patients. Material and Methods Between April 2014 and January 2017, 65 nodal lesions in 26 oligometastatic hormone-sensitive and castration resistant PC patients, were treated with SBRT using VMAT and flattening filter free beams. Prescribed doses and schedules of fractionation varied, ranging from 30 Gy in 5 fractions to 40 Gy in 4 fractions. Most commonly used schedules were 35 Gy in 5 fractions and 36 in Gy in 6 fractions. Biochemical response, acute and late toxicity were analyzed. In 45/65 (69 %) lesions were treated in castration-resistant PC patients, 20/65 (31%) in metastatic hormone sensitive PC patients. PET/CT was performed with Choline in 40/65 (62%) and 68-Ga PSMA in 25/65 (38%). Toxicity were evaluated using CTCAE v.4.0. Local control was assessed by means of PET/CT scan and PSA reduction. Results At a median follow-up of 12 months (range 3-26), a biochemical response was observed in 75% of treated cases. In all cases, imaging evaluation at 3 months after treatment was available: complete response was found in 56/65 (86%) cases and stable disease in 9/65 (14%) cases. No in-field recurrence was detected. Thus, overall response rate was 100%. In 11/65 (17%) cases out of field recurrence was reported. Median time to progression out of field (14%) was 3 months (range 3-27 months). At the time of analysis, one patient died for non-oncological causes. Twenty-two patients, among the 26 patients treated (85%), were still free of disease. SBRT was well tolerated: Only two patients experienced G1 acute gastrointestinal toxicity. Late toxicity was evaluated in patients with more than 6 months of follow-up. We did not observe any acute or late G2-G3 toxicity. Conclusion SBRT for oligometastatic lymph nodes in hormone- sensitive and castration resistant PC patients is feasible and well tolerated. Longer follow-up is needed to assess late toxicity and the impact of this impressive local control rate on clinical outcomes.