ESTRO 2023 - Abstract Book

S53

Saturday 13 May

ESTRO 2023

months (95% CI 48.0-62.7 months), 180 (60.8%) patients died, 46 (15.5%) developed BM at a median time of 10.8 months. The median overall survival was 29.9 months (95%CI 23.1-36.7). GTV was available for all patients, of which 266 GTVn and 274 GTVp were distinguishable. In all, 861 features were extracted. Univariate analysis showed that 3 GTV, 4 GTVn, and 2 GTVp features were significantly associated with BM development (p<0.05). Multivariate models showed that Wavelet-HLL first-order-Median (HR=1.62, 95% CI 1.04-2.51, p=0.03) was a significant GTV feature, Wavelet- HLL-first-order-Median (HR=2.21, 95% CI 1.32-3.68, p=0.002) and Wavelet-HHL-firstorder-Median (HR=1.61, 95% CI 1.05-2.46, p=0.03) were significant GTVn features, Wavelet-LLH-glcm-Idn (p=0.06) and Wavelet-LHH-glcm-Imc1 (p=0.06) were marginally significant GTVn features, Wavelet-HLH-glszm-Gray-Level-Non-Uniformity (HR=1.48, 95% CI: 1.16-1.90, p=0.002) and Wavelet-LLL glcm-Imc2 (HR=0.69, 95% CI: 0.51-0.94,p=0.02) were significant GTVp features (Table). The AUC of the GTV, GTVn, GTVp model ranged from 0.59-0.68, 0.65-0.78, 0.49-0.64, respectively (Figure).

Conclusion Radiomics features based on TRT planning CT have predictive value for BM development in stage III NSCLC. GTVn provided more predictive value than GTVp and GTV. OC-0090 T-lymphocytes and hypoxia predicts survival after brachytherapy in locally advanced cervical cancer T. Tramm 1 , J. Alsner 2 , P.S. Nielsen 1 , J.B. Georgsen 1 , J. Overgaard 2 , J.C. Lindegaard 3 1 Aarhus University Hospital, Pathology, Aarhus C, Denmark; 2 Aarhus University Hospital, Experimental Clinical Oncology, Aarhus C, Denmark; 3 Aarhus University Hospital, Oncology, Aarhus C, Denmark Purpose or Objective Presence of CD8 positive (CD8+), cytotoxic T-lymphocytes in treatment naïve tumor has been found to be a predictive factor for benefit of radiotherapy (RT) in breast cancer with improved distant tumor control translating into superior survival (1). Following employment of chemoradiation (CRT) and image guided adaptive brachytherapy (BT), loco-regional control in locally advanced cervical cancer (LACC) has improved considerably and systemic relapse is now the dominant problem. The aim of this study was to investigate, if presence of tumorinfiltrating T-lymphocytes is a prognostic factor in LACC. Materials and Methods Multiplex chromogen immunohistochemistry was performed on paraffin embedded biopsies containing pre-treatment tumor tissue obtained from 189/190 consecutive patients from a previous study on hypoxia in squamous cell LACC treated 2005 2016 (2). Subsets of T-lymphocytes was visualized using CD4, CD8, FOXP3 and AE1/3 as tumor marker. Area fraction of the various immune cells (area of immune cells/area of tissue) was determined by digital image analysis, and two groups were generated for each marker based on median values. Hypoxia status was reported previously (2). The FIGO2009 stage distribution among the 189 patients was IB-IIA 10%, IIB 64% and III-IVA 26%. Pathological pelvic nodes (N1) were found in 76 (40%) and para-aortic nodes (N2) in 23 (12%) patients. All patients received pelvic external beam RT of 45-50 Gy/25-30 fx including also the para-aortic region in 38 (20%). Concomitant weekly cisplatin was given to 145 (77%). All patients were treated with BT with mean CTV HR volume of 35 cm3 and a D90 of 92 Gy EQD2 . Endpoints were extra pelvic control (EPC), disease free survival (DFS), and overall survival (OS) calculated from start of CRT. EPC was analysed using Aalen-Johansen estimator and cause-specific Cox regression, DFS and OS using Kaplan-Meier estimator and Cox regression. Results Median observation times were 5.1 years (EPC) and 7.1 years (OS). EPC was obtained in 140/188 (74%). High levels of CD8+, CD4+, and FOXP3+ cells, and a ‘less’ hypoxic profile were significantly associated with improved OS (Figure 1). Similar trends were observed for EPC and DFS but only the association between hypoxia and DFS was significant. On continuous scales, CD4 and CD8 were correlated (Figure 2A). ‘Less’ hypoxia was significantly associated with high levels of CD4, CD8 (p values < 0.0001) but not with FOXP3 (Figure 2B). Conclusion Presence of pre-existing, tumorinfiltrating T-lymphocytes and hypoxic status are prognostic factors for overall survival for LACC with squamous cell histology after BT. High infiltration of CD4+ and CD8+ T-cells was found to correlate with a ‘less’