P2.03b-006 Distinct MR Imaging Features of Metastatic Lesions in Brain with Non-Small Cell Lung Cancer According to EGFR Mutation Status: Topic: Brain Meta

Abstract

It is often difficult to evaluate the status of EGFR mutation in non-small cell lung cancer (NSCLC) patients with brain metastases either from primary or metastatic lesions. Is it possible to ascertain the EGFR status and to guide the usefulness of TKI according to the MR imaging features of metastatic lesions in brain? Patients diagnosed with NSCLC from June 2014 through May 2015 were identified synchronous brain metastases based on enhanced magnetic resonance imaging (MRI). The variables of metastatic brain tumor included the numbers and the size of the brain lesions, the size of the associated peritumoral brain edema (PTBE) measured with brain MRI. The information was obtained mainly by transbronchial lung biopsy, percutaneous needle lung biopsy or cervical lymph nodes biopsy about EGFR mutation status. Among 156 patients, 41 had the exon 19 deletion, 48 had the exon 21 L858R point mutation, and 67 had the wild-type EGFR. The exon 19 deletion group and exon 21 point mutation group had smaller peritumoral brain edema than did the wild-type group (P = 0.002 and P = 0.010, respectively). Different from the wild-type group, the exon 21 point mutation group showed more multiple brain tumors (P = 0.020). There was no significant difference about the size of the largest brain tumors in either exon 19 deletion group or exon 21 point mutation group when compared with the wild-type group (P = 0.077 and P = 0.051, respectively), but the metastatic brain lesions were inclined to smaller in EGFR mutation groups. Specific features of MRI in brain metastatic lesions were found in NSCLC with EGFR mutation，including smaller peritumoral brain edema and more lesions than did those with wild-type EGFR. Meanwhile, there was the trend that the size of the largest brain lesion was smaller in EGFR mutation groups. Accumulation of more knowledge was needed to depend on radiomics to make a quantifying analysis of EGFR mutation status.