P2.01-66 Comparison of EGFR Mutation Status in Tissue and Plasma Cell-Free DNA Detected by ARMS in Advanced Lung Adenocarcinoma Patients

Abstract

Background: We evaluate the correlation of clinical staging on positron emission tomography-computed tomography (PET-CT) and pathologic staging and the prognostic value of PET-CT after induction chemotherapy in patients with locally advanced Non-Small Cell Lung Cancer (NSCLC). Method: We analyzed 42 cases of clinical stage IIIA-N2 NSCLC who receive 2 to 4 cycles of pre-operative chemotherapy with or without radiation followed by curative resection. The maximum standard uptake value (SUVmax) of the suspected lesion on PET-CT was recorded. PET-CT findings after induction chemotherapy were compared with those of initial PET-CT and pathology after surgery. Result: The accuracy of PET-CT in restaging of the primary tumor after induction chemotherapy was 50.0%. 18 (42.8%) of 42 patients were underestimated ycT stage, and 3 (7.1%) of 42 patients was overestimated ycT stage by PET-CT scan. The accuracy of PET-CT in restaging of the nodal disease was 71.4%. 6 (14.3%) of 42 patients were underestimated ycN stage, and 6 (14.3%) of 42 patients were overestimated ycN stage as compared with pathologic staging. The 2-year overall survival (OS) and relapse-free survival (RFS) rate were 68.5% and 40.9%, respectively. Complete responders (ycT0N0M0) on PET-CT after induction chemotherapy had a significantly longer RFS time than did incomplete responders (28.3 months versus 9.1 months, P ¼ 0.021). Conclusion: Complete response on PET-CT after induction chemotherapy with or without radiation was a good prognosticator for RFS in stage IIIA-N2 NSCLC patients who received surgery. However, response evaluation on PET-CT after induction chemotherapy should be interpreted with caution due to its unacceptable accuracy.