ESTRO 2023 - Abstract Book

S1221

Digital Posters

ESTRO 2023

2 fraction SBRT to the prostate can be planned online whilst meeting the clinical goals set out in the HERMES protocol. We plan to report an interim toxicity analysis after the first 20 patients are 12 weeks out from completing their radiotherapy. Acknowledgments

The HERMES trial is funded by the JP Moulton foundation.

References

1. Westley R et al (2020) https://pubmed.ncbi.nlm.nih.gov/35093251/ 2. Winkel D et al (2019) https://pubmed.ncbi.nlm.nih.gov/31341976/ 3. de Mol van Otterloo SR et al (2020) https://pubmed.ncbi.nlm.nih.gov/33014774/

PO-1502 Prostate cancer in younger patients: Does it make a difference in oncological outcomes?

N. Fourati 1 , M. Frikha 2 , S. Zouari 1 , F. Dhouib 1 , W. Siala 1 , L. Farhat 1 , W. Mnejja 1 , J. Daoud 1

1 Habib Bourguiba Hospital Faculty of Medicine University of Sfax, Radiotherapy Department, Sfax, Tunisia; 2 Habib Bourguiba Hospital Faculty of Medicine University of Sfax, Radiotherapy Department , Sfax, Tunisia Purpose or Objective Prostate cancer is considered a disease of older men, but today over 10% of new diagnoses occur in men aged ≤ 65 years. The forms of younger patients are considered more aggressive, but the literature does not adequately explore the data for this patient population. Our retrospective study aimed to compare the prognosis of prostate cancer in the young patient group to the common population. Materials and Methods From November 2011 to January 2019, 181 patients were treated with conformal radiotherapy, with or without hormonotherapy, for prostate cancer including 42 patients aged ≤ 65 years (23.2%) (Group 1). The second group included 94 patients aged between 65 and 75 years. Overall survival (OS) was calculated from histological diagnosis to the date of death or the date of last information. Biochemical recurrence-free survival (BRFS) was calculated from the end of radiotherapy to the date of biochemical relapse or the date of last information. The Event-free survival (EFS) was calculated from the end of radiotherapy to the date of the specific event (specific death, clinical or radiological or biochemical relapse) or the date of last information. Survival analysis was made according to the Kaplan-Meier method. Log-rank test was used to compare the survivals of the 2 groups. Results For group 1, the median radiotherapy dose was 76 Gy [70-78] was delivered. According to the NCCN classification: 3 patients (6.1%) had a low risk, 9 patients (18.3%) had an intermediate risk, 21 patients (42.8%) had a high risk, 10 patients (20.4%) had a very high risk, and 6 patients (12.2%) were metastatic. Radiotherapy was associated with hormonotherapy for 46 patients (93.8%): 7 patients (15.2%) for the short term and 39 patients (84.8%) for the long term. Prophylactic lymph node irradiation was given to 10 patients (20.4%) and curative irradiation to one patient (2%). For group 2, the median radiotherapy dose of 76 Gy [70-78] was delivered. According to the NCCN classification: 4 patients (4.2%) had a low risk, 56 patients (59.57%) had an intermediate risk, 37 patients (39.36%) had a high risk and 16 patients (17%) had a very high risk and 14 patients (14.89%) had metastatic disease. In this group,88 patients (93.6%) had HT for 21 patients (23.8%) in a short time and 67 patients (76.13%) in a long time. Node irradiation was given prophylactically in 26 patients (27.6%) and curatively in 6 patients (6.38%). The OS rates at 5 and 10 years were 93.7% and 78.7% for G 1 versus 92.7% and 56% for G 2 (p=0.9). The BRFS rates at 5 and 10 years were 77.7% and 77.7% for G 1 versus 83% and 80.1% for G 2 (p=0.7). The EFS rates at 5 and 10 years were 72.1% and 72.1% for G 1 versus 80.6% and 77.8% for G 2 (p=0.4). Conclusion In our series, prostate cancer in young patients < 65 years does not appear to be more aggressive than that in older patients (65-75 years). all survival parameters were comparable between the 2 groups suggesting an evolutionary similarity between the 2 entities.

PO-1503 Early clinical evaluation of a GPS-based gating approach during prostate cancer SBRT

S. Slimani 1 , B. Yanes 1 , G. Guibert 1 , L. Hirschi 1 , T. Risse 1 , G. Faessler 1 , J. Abel 2 , P. Weber 1 , B. De Bari 1

1 Réseau Hospitalier Neuchâtelois, Radiation Oncology, La Chaux-de-Fonds, Switzerland; 2 Réseau Hospitalier Neuchâtelois, Radiation Oncology, La Chaux-de Fonds, Switzerland

Purpose or Objective To report early clinical results of an innovative EM trasmitter-based gating for dose-escalated prostate SBRT.

Materials and Methods From 24.01.2022 to 19.08.2022, 20 patients received prostate SBRT using flattening filter-free (FFF) volumetric modulated arc therapy (VMAT) for a primary PCa. A total dose of 36.25Gy was delivered in 5 fractions to the prostate + 2mm and a simultaneous integrated boost up to 40Gy was delivered on the dominant intraprostatic lesion(s) visible at MRI + 2mm. The