ESTRO 2020 Abstract book

S42 ESTRO 2020

paraffin-embedded (FFPE) biopsies. Prognostic validation of the nanoString® assay was performed in FFPE samples from the retrospective and VorteX cohorts. Intra-tumour heterogeneity was assessed in patients (n=10) with multiple biopsies and compared with CAIX expression. Results In the RNA-sequencing VorteX cohort, data were generated for 125/140 patients with available tissue. There was a trend towards poor disease-free survival (DFS) in patients with hypoxic tumours (HR 1.68 95% CI 0.95-2.98 p=0.061). Taqman® array cards and nanoString® demonstrated excellent pass rates and reproducibility. The nanoString® was more sensitive, required lower input and can measure more genes simultaneously. The gene signature showed considerably less intra-tumour heterogeneity than a single marker (figure 1). The nanoString® assay produced a result for 126/127 (99.2%) and 154/159 (96.9%) of patients with sufficient RNA yield and classified 41.3% and 44.8% of samples as hypoxic from the retrospective and VorteX cohorts, respectively. In a univariate analysis patients with hypoxic tumours had worse disease free survival in both cohorts (retrospective HR 2.302 95% CI 1.182-4.486 p=0.0083, VorteX HR 1.687 95% CI 1.013-2.81 p=0.0377) (figure 2).

Conclusion A hypoxia signature nanoString® assay with excellent technical performance is prognostic in two independent cohorts of patients with high-grade tumours, including the phase III VorteX radiotherapy trial. The assay could identify high-risk patients for adjuvant chemotherapy trials. OC-0087 Preoperative Hypofractionated Radiation Therapy for Soft Tissue Sarcomas of Extremity and Trunk F. Navarria 1 , A. Lauretta 2 , E. Palazzari 1 , R. Innocente 1 , M. Gigante 1 , A. Caroli 1 , V. Canzonieri 3 , A. Buonadonna 4 , F. Gherlinzoni 5 , J. Polesel 6 , G. Bertola 2 , A. De Paoli 1 1 Centro di Riferimento Oncologico di Aviano IRCCS, Radiation Oncology, Aviano, Italy ; 2 Centro di Riferimento Oncologico di Aviano IRCCS, Surgical Oncology, Aviano, Italy ; 3 Centro di Riferiemnto Oncologico di Aviano IRCCS, Pathology, Aviano, Italy ; 4 Centro di Riferimento Oncologico di Aviano IRCCS, Medical Oncology, Aviano, Italy ; 5 Ospedale di Gorizia- Monfalcone, Orthopedic, Gorizia, Italy ; 6 Centro di Riferimento Oncologico di Aviano IRCCS, Cancer Epidemiology, Aviano, Italy Purpose or Objective Radiation Therapy (RT) and Conservative Surgery (S) is a well established approach in most part of extremity and superficial trunk soft tissue sarcomas (STS). Preoperative RT, with a dose of 50Gy/25 fractions (frs), 2Gy fr, is the emerging option as preferred option, compared to postoperative RT, for better long-term anatomic and functional results. Hypofractionated RT represent an increasingly interest in STS. We evaluated feasibility and oncologic outcomes of preoperative moderate hypofractionated RT in this setting of STS patients (pts) treated at our Institute. Material and Methods A retrospective analysis of cohort of consecutive pts was performed. Pts selection included no high-risk pts candidate to (neo)adjuvant chemotherapy and no critical tumor sites. Advanced RT techniques such as 3D-CRT and IMRT-IGRT were used. A moderate hypofractionation of RT dose of 40.5Gy/18frs, 2,25Gy/fr, was planned.