ESTRO 2022 - Abstract Book

S402

Abstract book

ESTRO 2022

Conclusion The BrainAGE framework shows a significantly higher rate of biological aging for glioma patients after radiotherapy. Due to the lack of pre-engineered features, BrainAGE can provide an overview of the spatial post-radiation changes in the brain, taking the entire brain volume into account. The well-defined areas obtained from the saliency maps could indicate importance for future research into post-radiotherapy changes in the brain. Applying this framework provides further insights into radiation-induced accelerated aging. Use of BrainAGE may eventually guide radiation therapy planning and contribute to expectation management of treatment side effects.

OC-0457 Modeling outcome after salvage post-prostatectomy radiotherapy: impact of pelvic nodes irradiation

M. Olivieri 1 , C. Cozzarini 2 , A. Magli 3 , D. Cante 4 , B. Noris Chiorda 5 , F. Munoz 6 , A. Faiella 7 , E. Olivetta 8 , M.A. Signor 3 , C. Piva 4 , B. Avuzzi 5 , L. Ferella 6 , A. Pastorino 8 , E. Garibaldi 9 , M. Gatti 9 , L. Rago 10 , T. Statuto 11 , S. Broggi 12 , A. Fodor 13 , C. Deantoni 13 , T. Rancati 14 , G. Sanguineti 7 , R. Valdagni 5 , N. Di Muzio 13 , C. Fiorino 12 1 San Raffaele Scientific Institute, Medical Physics, Milano, Italy; 2 San Raffaele Scientific Instite, Radiotherapy, Milano, Italy; 3 Azienda Ospedaliero Universitaria S. Maria della Misericordia, Radiotherapy, Udine, Italy; 4 ASL TO4 Ospedale di Ivrea, Radiotherapy, Ivrea, Italy; 5 Fondazione IRCCS Istituto Nazionale dei Tumori, Radiotherapy, Milano, Italy; 6 Ospedale Regionale Parini-AUSL Valle d’Aosta, Radiotherapy, Aosta, Italy; 7 IRCCS Istituto Nazionale dei Tumori “Regina Elena”, Radiotherapy, Roma, Italy; 8 A.O.SS. Antonio e Biagio, Radiotherapy, Alessandria, Italy; 9 IRCCS Ospedale di Candiolo, Radiotherapy, Torino, Italy; 10 Centro di Riferimento Oncologico della Basilicata (IRCCS-CROB), Radiotherapy, Rionero in Vulture, Italy; 11 Centro di Riferimento Oncologico della Basilicata (IRCCS-CROB) , Radiotherapy, Rionero in Vulture, Italy; 12 San Raffaele Scientific Institute, Medical Physics, Milano, Italy; 13 San Raffaele Scientific Institute, Radiotherapy, Milano, Italy; 14 Fondazione IRCCS Istituto Nazionale dei Tumori, Medical Physics, Milano, Italy Purpose or Objective Comprehensive predictive models of long-term biochemical-relapse-free survival (bRFS) after post-prostatectomy salvage radiotherapy (SRT) are lacking. A previously realized radiobiology-based formula was adapted to incorporate the impact of pelvic node irradiation (PNI) and was applied to a multi-Institute cohort treated with SRT to estimate the long-term impact of PNI. Materials and Methods bRFS may be expressed by a Poisson-based equation ((K x (1- exp(- α effD))CxPSA), including pre-SRT PSA, the radiosensitivity parameter α eff, the clonogen density C (assuming a pre-SRT PSA=1 ng/mL), the prescribed 2-Gy equivalent dose D, and a factor K=(1-Bx λ xPSA) representing the detrimental impact on post-SRT bRFS due to clonogens outside the irradiated volume at SRT, with λ being the recovery of bRFS obtainable with PNI. Data of 795 pT2-pT3a/pT3b, pN0/pN1/pNx patients (pts) treted in 8 Institutes with a 5-year minimum follow-up and a pre-RT PSA ≤ 2 ng/mL were randomly split into training (n=528) and validation (n=267) cohorts; data of the training cohort were fitted by the least square method. Separate fits were performed on two class-risk groups, based on the most robust, clinically significant predictors resulting from a multi-variable Cox regression analysis. Model performances were compared against true data by calibration plots and tested in the validation group.

Results