ESTRO 2022 - Abstract Book

S1051

Abstract book

ESTRO 2022

LA-NSCLC patients treated with SABR had optimal LC and promising overall survival in absence of ≥ G3 toxicity. Our prospective results provide an attraction to evaluate this approach in selected LA-NSCLC patients unfit to concurrent ChT- cRT.

PO-1245 Radiomics features and functional radiosensitivity enhances prediction of acute pulmonary toxicity.

V. Bourbonne 1,2 , F. Lucia 1,2 , V. Jaouen 2,3 , J. Bert 2 , M. Rehn 1 , M. Hatt 2 , O. Pradier 1,2 , D. Visvikis 2 , U. Schick 1,2

1 University Hospital, Radiation Oncology, Brest, France; 2 Université de Bretagne Occidentale, LaTIM, IMR 1101 INSERM, Brest, France; 3 Insitut Mines, Telecom Atlantique, Brest, France Purpose or Objective (Chemo)-radiotherapy is the standard treatment for patients with locally advanced lung cancer (LALC) not accessible to surgery. Despite strict application of dose constraints, acute toxicities such as acute pulmonary toxicity (APT) remain frequent, and may impact treatment’s compliance and patients’ quality of life. Two separate predictive models were previously developed: the Rad-model combined 6 radiomics features and achieved high results but consists in a posteriori evaluation of the APT risk. The Pmap-model was developed combining several clinical and dosimetric features after defining a specific zone in the posterior right lung and further validated in a prospective cohort. In the present study, we aim to combine all features to develop and validate a new model for prediction of the APT risk in two cohorts treated by volumetric-arctherapy (VMAT). Materials and Methods For the training cohort, we retrospectively included all patients treated in our institution by VMAT for a LALC between 2015 and 2018. APT was scored according to the CTCAE v4.0 scale. All clinical (age, tobacco history, BPCO and VEMS) and dosimetric features (V5 LungH , V10 LungH , DMean LungH and DMean Lungs , V30 Lungs and V40Heart as well as the mean dose to the pre- defined Pmap zone (DMean Pmap )) were combined using a neural network approach and then applied to an observational prospective cohort for validation. To compensate for imbalanced data, the SMOTE package was used before model building. The model was evaluated using the Area under the curve (AUC) and the balanced accuracy (Bacc: mean of the sensitivity and specificity). Results 165 and 42 patients were included in the training and validation cohorts, with respective APT rates of 22.4% and 19.1%. In the validation cohort, while the Rad-Model and the Pmap-Model achieved AUCs of 0.83 and 0.81 respectively, the combined model (Comb-Model) achieved an AUC of . With their respective thresholds defined on the training cohort, each model resulted in a Bacc of 0.82, 0.82 and 0.90 for the Rad, Pmap and Comb-models, respectively. Conclusion Addition of radiomics and DMean Pmap to usual clinical and dosimetric features enhances the accuracy of the newly developed prediction model. This model could be useful for a better assessment of the APT risk and open new treatments possibilities such as new treatment combinations. A. Botticella 1 , A. Levy 1 , O. Mercier 2 , G. Auzac 1 , A. Traore-Diallo 3 , M. Frelaut 4 , P. Pradere 2 , C. Caramella 5 , I. Kasraoui 6 , B. Besse 4 , D. Planchard 4 , C. Le Pechoux 1 1 Gustave Roussy, Radiation Oncology, Villejuif, France; 2 Marie-Lannelongue Hospital, Thoracic and Vascular Surgery and Heart-Lung Transplantation Department, Plessis Robinson, France; 3 Gustave Roussy , Radiation Oncology, Villejuif, France; 4 Gustave Roussy, Oncology Department, Villejuif, France; 5 Marie-Lannelongue Hospital, Radiology Department, Plessis Robinson, France; 6 Gustave Roussy, Radiology Department, Villejuif, France Purpose or Objective The objective of this retrospective study was to assess the efficacy and the safety of the SBRT in patients with prior pneumonectomy and a new lung malignancy. Materials and Methods We retrospectively identified the patients who received SBRT post-pneumonectomy from a single institution database of patients treated with SBRT from January 2013 and June 2021. Image-guided SBRT was delivered either with a Cyberknife or with a linear accelerator (in VMAT or with static coplanar beams). Lesions localised in the inferior lobes were treated using deep-inspiration breath-hold (DIBH). The prescription dose was 26-60 Gy in 7.5- to 26-Gy fractions delivered to the PTV (according to a risk-adapted approach). All patients underwent a restaging 18 F-PET-CT scan before SBRT. A biopsy of the lung lesion was not mandatory, if the lesion was hyper-metabolic at a 18 F-PET-CT scan and growing on multiple CT scans. Each patient was discussed in a multidisciplinary team before SBRT. The primary endpoint was toxicity (lung, cardiac, oesophageal), graded using the Common Toxicity Criteria (CTC) v. 4.03. The secondary endpoints were local control, distant metastases-free survival and overall survival (OS). Dosimetric parameters were collected. PO-1246 Lung SBRT after pneumonectomy

Results