ESTRO 2023 - Abstract Book

S1195

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ESTRO 2023

Acute genitourinary (GU) toxicity: 25p (46%) G1, 3p (6%) G2; none G3 toxicity and 26p (48%) had no toxicity. Acute gastrointestinal (GI) toxicity: 5p (9%) G1, 4p (8%) G2; none G3 and 45p (83%) G0. Late toxicity was assessed in 44p (81%) with a follow up of more than three months. Late-GU adverse-effects: 38p (86%) G0, and 3p (7%) had G1 and G2 respectively but no patients had grade ≥ 3 late GU toxicity. Late-GI adverse-effects: 39p (89%) had no late complications, 3p (7%) G2 and 2p (5%) G3. On follow-up, no patient had persistent symptoms at 12 months post-treatment, since these were adequately resolved. Conclusion UHF SABR with a urethra sparing protocol seems to be a feasible and safe option in high risk cancer prostate. However, higher number of treated patients with longer follow-up is necessary to confirm observed results.

PO-1476 Extreme hypofractionated SBRT for elderly prostate cancer patients: results of a phase II trial

R. Carbonara 1 , F. Gregucci 1 , A. Surgo 1 , M.P. Ciliberti 1 , F.C. Di Guglielmo 1 , E. Paulicelli 1 , I. Bonaparte 1 , A. Fiorentino 1

1 General Regional Hospital F.Miulli, Radiation Oncology Department, Acquaviva delle Fonti (Bari), Italy

Purpose or Objective Stereotactic body radiation therapy (SBRT) with extreme hypofractionation is replacing prostatectomy mostly in case of low risk prostate cancer.However, in selected cases of intermediate/high risk, it could be a justified treatment.This study evaluated safety and efficacy of Linac-based SBRT in elderly patients affected by prostate cancer(PC). Materials and Methods Men ≥ 70 years with localized PC were enrolled.The SBRT schedule was 35 Gy in 5 fractions administered with Volumetric Modulated Arc Therapy (VMAT) in 1 or 2 weeks based on target volume and urinary symptoms.According to risk group, androgen deprivation therapy(ADT) was prescribed in adequate cases. Urinary symptoms were evaluated at baseline using the International Prostate Symptom Score (IPSS).Toxicity was assessed at the end of treatment, 2 weeks after SBRT and during follow-up using the Common Terminology Criteria for Adverse Events(CTCAE).PSA values were recorded before treatment and during follow-up as biochemical response criteria. Results Between July 2019-September 2021, 111 patients were treated.Median age was 77 years (range 70-86); 33% were low-risk, 48% favorable/unfavorable intermediate-risk and 19% high-risk group. Median pre-treatment PSA was 6.61 ng/ml(range 0.2 40 ng/ml). ADT was administrated in 58 patients.Median PTV was 99.5cc(range 51-192.2).Median baseline IPSS was 6(range 0-19).At the end of treatment, no acute genitourinary(GU) or gastrointestinal(GI) toxicities ≥ G2 were observed.At 2-3 weeks after treatment, 3 patients reported G2 subacute GU toxicity (urinary frequency, urinary tract pain and urinary retention), while 14 patients referred GI toxicity (rectal tenesmus).During the last follow up, 26 and 2 patients reported, respectively, G1 and G2 GU toxicity, while 22 and 1 cases described, respectively, G1 and G2 GI toxicity.No late toxicities ≥ G3 were recorded.At a median follow up of 23 months(range 8-35), excellent biochemical disease control was achieved in all cases (median PSA 0.5 ng/ml(range 0-6.46)).The univariate analysis showed a statistically significant relationship between GU toxicity and the following variables: IPSS(p 0.03), PTVvolume(p 0.05), Dmax PTV(0.01), urethra-sparing (p 0.03) and late toxicity_GI(0.03). The multivariate analysis confirmed statistically significant association for urethra-sparing (OR 0.39[95%CI 0.013-1] p 0.05) and late-toxicity_GI(OR 2.44[95%CI 6.3-9.4] p 0.04).Regarding to GI toxicity, the univariate analysis showed a statistically significant relationship with the following variables: IPSS(p 0.002), day RT (p 0.02) and late-toxicity_GU(p <0.001).The multivariate analysis confirmed statistically significant association for late-toxicity_GU(OR 43.2[95%CI 10-182] p <0.001)and a correlation with Dmax rectum (OR 0.23[95%CI 0.05-1] p 0.05). Conclusion Linac-based SBRT in elderly patients affected by localized PC is feasible and well tolerated with excellent biochemical disease control.Longer follow-up is needed to assess late toxicity and long-term clinical outcome. V. DUQUE SANTANA 1 , A. Diaz Gavela 2 , M. Recio 3 , L.L. Guerrero 2 , M. Peña 2 , S. Sanchez 2 , I.J. Thuissard 4 , C. Andreu 5 , D. Sanz Rosa 4 , F. Lopez-Campos 6 , A. Gómez-Iturriaga 7 , Y. Molina 8 , E. Del Cerro Peñalver 9 , F. Couñago 10 1 Quirónsalud University Hospital and La Luz Hospital, Radiation Oncology , Madrid, Spain; 2 Quirónsalud University Hospital and La Luz Hospital, Radiation Oncology, Madrid, Spain; 3 Quirónsalud University Hospital, Radiology, Madrid, Spain; 4 European University of Madrid , Biomedical and health sciences, Madrid, Spain; 5 European University of Madrid , Biomedical and health sciences, Madrid, Spain; 6 Ramón y Cajal University Hospital, Radiation Oncology, Madrid, Spain; 7 Cruces University Hospital, Radiation Oncology, Barakaldo, Spain; 8 Quironsalud University Hospital, Medical Physics, Madrid, Spain; 9 Quirónsalud University Hospital and La Luz Hospital, Radiation Oncology, Madrid, Spain; 10 San Francisco de Asís and La Milagrosa Hospitals, GenesisCare. , GenesisCare Madrid Clinical Director. National Chair of Research and Clinical Trials. GenesisCare Spain, Madrid, Spain Purpose or Objective To analyze the 10y-biochemical relapse-free survival(BRFS), locoregional relapse-free survival(LRFS), metastasis-free survival(MFS) and overall survival(OS) in patients diagnosed with non-metastatic prostate adenocarcinoma treated with PO-1477 10-year outcomes of risk-adapted radiotherapy defined by multiparametric MRI for prostate cancer