ESTRO 2022 - Abstract Book

S1168

Abstract book

ESTRO 2022

IMRT prescribing high doses with radical intent. Overall survival, disease-free survival, biochemical progression-free survival, distant progression-free survival and metastases control were evaluated. Toxicity were evaluated with CTCAE4.3 Scale. Results Median follow up was 24.2 months (Range 8-43.9). We included 37 patients with 40 lesions. 25 Bone metastases and 15 adenopathies were finally treated. 48,6% were homono-sensitive, 19% castrate resistant and 32,4% became castrate- resistant during followup. 89% were being treated with ADT. Treatment was administered with intensity-modulated radiotherapy guided by daily image by Conebeam and multi-dampening SBRT-system. Treatment dose was 18Gy/24Gy single session or 30 Gy in 3 fractions every other day for bone lesions and 12Gy/18Gy single session or 30 Gy in 3 fractions every other day for adenopathies. Disease-free survival, biochemical progression-free survival and distance-free relapse-free survival were 73%, 75,6% and 78,3% respectively. Overall survival was 94,6 % and metastases control at 2 years was 83,7%. Toxicity were evaluated with CTCAE4.3 Scale. 33 patients (90%) had no acute genitourinary toxicity and 4 (10%) presented grade 1 acude genitourinary toxicity. For the gastrointestinal toxicity, 32 patients (86,5%) did not present any toxicity while 5 (13,5%) had grade 1 toxicity. Only one patient suffered late-toxicity, pathological fracture 8 months later. Conclusion SBRT used in oligometastatic prostate cancer could provide optimal control and result in a safe technique that provides the patient with an alternative in the natural history of their disease. 1 Institut Bergonié, Radiation Oncology, Bordeaux, France; 2 Institut Bergonié, Oncologic Imaging, Bordeaux, France; 3 Clinique Saint Augustin, Urology, Bordeaux, France; 4 Institut Bergonié, Nuclear Medicine, Bordeaux, France; 5 Institut Bergonié, Medical Oncology, Bordeaux, France Purpose or Objective In-field prostate cancer (PCa) oligo-recurrence after pelvic radiotherapy is a challenging situation, for which metastasis- directed treatments may be beneficial but options for focal therapies are scarce. Materials and Methods We retrospectively reviewed data for patients with 3 or less in-field oligo-recurrent nodal, bone and/or locally recurrent (prostate, seminal vesicles or prostatic bed) PCa lesions after radiation therapy, identified with molecular imaging (PET and/or MRI) and treated by focal ablative therapy (cryotherapy or radiofrequency) at the Institut Bergonié between 2012 and 2020. Chosen endpoints were the post-procedure PSA response (partial defined as a >50% reduction, complete as a PSA<0.05ng/mL), progression-free survival (PFS) defined as either a biochemical relapse (defined as a rise >50% of the Nadir and above 2ng/mL), radiological relapse (on any imaging technique), decision of treatment modification (hormonotherapy initiation or line change) or death; and tolerance. Results Forty-three patients were included. Diagnostic imaging was mostly 18F-Choline positron emission tomography/computerized tomography (PET/CT) (75.0%), prostate specific membrane antigen (PSMA) PET/CT (9.1%) or a combination of pelvic magnetic resonance imaging (MRI), CT and 99mTc-bone scintigraphy (11.4%). PSA response was observed in 41.9% patients (partial in 30.3%, complete in 11.6%). In the hormone-sensitive exclusive focal ablation group (n=31), partial and complete PSA response were 32.3% and 12.9% respectively. Early local control (absence of visible residual active target) on the post-procedure imaging was achieved with 87.5% success. After a median follow-up of 30 months (IQR 13.3-56.8), the median PFS was 9 months overall (95% CI, 6-17), and 17 months (95% CI, 11-NA) for PSA responders. Complications occurred in 11.4% patients, with only 1 grade IIIb Dindo-Clavien event (uretral stenosis requiring endoscopic uretrotomy). Conclusion In PCa patients showing in-field oligo-recurrence after pelvic radiotherapy, focal ablative treatment is a feasible option, possibly delaying a systemic treatment initiation or modification. These invasive strategies should preferably be performed in expert centers and discussed along other available focal strategies in multi-disciplinary meetings. PO-1377 Focal thermoablative therapy after pelvic radiotherapy for in-field prostate cancer oligo-recurrence N. Giraud 1 , X. Buy 2 , N. Vuong 3 , R. Gaston 3 , A. Cazeau 4 , V. Catena 2 , J. Palussiere 2 , G. Roubaud 5 , P. Sargos 1

PO-1378 An Alternative Salvage-Radiotherapy For Recurrent Prostate Cancer After Ldr-Brachytherapy

O. Muñoz Muñoz 1 , E. Gomis Selles 2 , A.M. Burgueño Caballero 2 , P. Cabrera Roldán 2 , D.M. Muñoz Carmona 2 , B.D. Delgado Leon 2 1 H. U. Virgen del Rocio, Oncology Radiation Therapy, Sevilla, Spain; 2 Hospital Universitario Virgen del Rocio, Oncology Radiation Therapy, SEVILLA, Spain Purpose or Objective This retrospective study evaluated at the tolerability and outcomes of salvage external beam radiotherapy (S-EBRT) for locally recurrent prostate cancer (LRPC) after definitive prostate brachytherapy (BQ)