ESTRO 2022 - Abstract Book

S229

Abstract book

ESTRO 2022

Alessandria, Italy; 21 Azienda U. S. L. della Valle d'Aosta, Radiation Oncology, Aosta, Italy; 22 Tor Vergata University, Radiation Oncology, Rome, Italy; 23 Department of Neuroscience, Imaging and Clinical Sciences, "G. D'Annunzio" University of Chieti-Pescara, Chieti, Italy; 24 "SS Annunziata" Hospital, "G. D'Annunzio" University of Chieti-Pescara, Radiation Oncology Unit, Chieti, Italy Purpose or Objective Few prognostic factors has been recognised in squamous cell carcinoma of the anus (ASCC). Some are related to patient (gender), others to tumor (size, nodal involvement, HPV status). No laboratory index is currently validated as a prognosticator to guide clinical decision-making. We recently developed a prognostic scoring system based on laboratory inflammation parameters, [Hemo-Eosinophils-Inflammation (HEI) index], including baseline hemoglobin level, the systemic inflammatory index (platelet x neutrophil/lymphocyte), and eosinophil count. HEI was shown to discriminate prognostic groups for disease-free (DFS) and overall (OS) survival in ASCC treated with concurrent chemoradiation (CHT-RT). We tested the accuracy of the model on a multicentric cohort for external validation. Materials and Methods Patients treated with CHT-RT with intensity-modulated techniques were enrolled from a national network and characteristics were collected, with baseline serum biomarkers. The Kaplan–Meier curves for DFS and OS according to HEI risk groups were calculated and the log-rank test was used to test the difference in survival estimates. Cox proportional hazards models were used to assess the influence of prognostic factors on DFS and OS. The exponential of the regression coefficients provided an estimate of the hazard ratio (HR) and the 95% confidence interval (95%CI). All p-values were two- tailed and a p-value<0.05 was statistically significant. For model discrimination, we determined Harrell's C-index, Gönen & Heller K Index and the explained variation on the log relative hazard scale based on D statistic. Results A total of 635 patients was available for the analysis. Proportional hazards were adjusted for age, gender, tumor stage, chemotherapy and radiotherapy. Two-year DFS was 77%(95%CI:72.0-82.4) and 88.3%(95%CI:84.8-92.0%) in the HEI high- and low- risk groups, respectively. Two-year OS was 87.8%(95%CI:83.7-92.0) and 94.2%(95%CI:91.5-97) in the same 2 groups (Figure.1). Multivariate Cox proportional hazards model showed a HR=2.02 (95%CI:1.25-3.26; p=0.004) for the HEI high-risk group with respect to OS and a HR= 1.53 (95%CI:1.43-3.40; p=0.029) for DFS (Table.1). Harrel C-indexes were 0.682 and 0.659 in the validation dataset, with respect to OS and DFS, respectively. Gonen-Heller K indexes were 0.672 and 0.705, respectively.