EP1.01-31 PET CT Radiogenomic Depiction in PDL1 Expression in Lung Cancer in Indian Population

Abstract

Non small cell lung cancer (NSCLC) represents an area of paramount importance wherein patients undergo testing for targetable genetic alterations. Association between the imaging and molecular phenotypes needs to be explored highlighting the growing importance of classifications based on radio genomic characterization. This study was conducted to evaluate the correlations between the radiologic and molecular phenotypes in patients with NSCLC. 211 patients with lung cancers during the study period of one year from October 2017 till November 2018 in our institution and undergoing both radiologic (PET-CT) and molecular investigations [Programmed death ligand 1 (PDL1)] were included in the study. Both quantitative and qualitative CT findings were evaluated and correlated with the molecular findings. Quantitative data included SUV max obtained from PET component of CT and maximum diameter of lesion according to the RECIST criteria. Qualitative data recorded included location, pleural tail, pleural effusion, pericardial effusion, opacity, margins, calcifications, obstructive changes, pleural nodules, lung nodules, invasion, air bronchogram, emphysema, pulmonary fibrosis, mediastinal lymph nodes and distant metastasis. Statistical analysis was performed to evaluate the association of the qualitative features with the molecular expression. Receiver operating characteristic curves (ROC) were drawn and the corresponding area under curve (AUC) was calculated. P-values <0.05 were considered significant. PDL1 expression was observed in 69 patients and 13/14 females and 29/34 non-smokers showed the expression (p-value <0.0001). A total of 1, 19, 22 and 27 patients had <1%, 1-10%, 10-50% and >50% PDL1 expression. SUV max was 11.7 ± 3.7 in the group with PDL1 expression. Correlations were observed between PDL1 expression and location (p-value <0.0001), pleural tail (p-value <0.0001), pleural effusion (p-value <0.0001), obstructive changes (p-value 0.001), pleural nodule (p-value 0.001), lung nodules (p-value <0.0001), air bronchogram (p-value <0.0001), emphysema (p-value <0.0001), mediastinal nodes (p-value <0.0001) and distant metastasis (p-value <0.0001). PDL1 expression correlated with pulmonary fibrosis (p-value 0.001). In ROC curves, in case of PDL1 expression, the AUC was 0.728 on the basis of length. The correlation between CT findings and molecular findings highlights the importance of newer radio genomic based characterization for patients with NSCLC for better diagnostic and prognostic approaches.