[Disparities of EGFR mutations between Biopsy and Rebiopsy in Non-small Cell Lung Cancer Patients].

Background: Epidermal growth factor receptor (EGFR)-based targeted therapy improves the survival of patients with advanced lung adenocarcinoma harboring EGFR mutations. However, factors including treatment or heterogeneity partly contribute to EGFR genetic status alteration between baseline and disease progresses (PD). The aim of this study is to compare difference of EGFR mutations between biopsy and rebiopsy in real world.
Methods: Data from 61 paired specimens performed EGFR testing in Jilin Provincial Cancer Hospital between January 2015 and December 2017 were collected and analyzed. The specimens were collected at baseline and PD, confirmed by histology or cytology and categorized as tumor tissue, malignant pleural effusion or plasma. All patients were naive and received chemotherapy or targeted therapy as first-line treatment. Amplification Refractory Mutation System (ARMS) was used to detect EGFR mutations.
Results: EGFR mutation rate in tumor tissue, pleural effusion or blood was 90.2% vs 88.5%, 6.6% vs 6.6% and 3.2% vs 4.9% at baseline or PD respectively and discrepancy was 72% and 36.3% for the same (n=50) or different (n=11) type of specimens. The EGFR mutation rate was 95.1% and 91.8% in patients before and after treatment, and the discrepancy was 63.9%, among which, 69.2% and 92.3% in chemotherapy-treated patients (n=13) with discrepancy to 46.1% (6/13), and 100.0% and 91.7% in EGFR-TKI-treated patients (n=48) with discrepancy to 70.8%. There were four types of alterations in terms of EGFR mutations: wild type turned into mutation (4.9%), mutation disappeared (8.2%), sensitive mutations transformed (1.6%), and new mutations appeared (49.1%).
Conclusions: In real world, the EGFR mutation status in advanced non-small cell lung cancer (NSCLC) patients altered significantly, due to tissue resources and therapeutic approaches, implying the importance of rebiopsy and real-time detection of EGFR mutation, in order to provide data to guide precise strategy in the following treatment.