P2.01-84 Patterns of Central Nervous System Metastases in EGFR Mutated or ALK Rearranged Non Small Cell Lung Cancer Patients

Abstract

Development of brain and leptomeningeal metastases has prognostic and therapeutic implications in oncogene driven non small cell lung cancer (NSCLC). A rising trend is being observed in the incidence of central nervous system (CNS) metastases in such populations, probably due to better imaging techniques as well as improved survival of patients. The presence of EGFR and ALK mutations could have a significant impact on the pattern of metastatic disease spread. Data from the Indian subcontinent on this subject is scarce. The information gained from this study may have clinical relevance in today’s era of first line use of second and third generation tyrosine kinase inhibitors (TKIs). 286 EGFR mutated (220) or ALK rearranged (66) NSCLC patients were selected for this retrospective analysis. All patients with clinically suspected CNS metastases underwent contrast enhanced MR imaging of brain. Two groups of patients were identified as per their driver mutation status. The CNS lesions were analysed with regards to number, size, site (parenchymal or meningeal) and nature (morphological heterogeneity and central necrosis) Incidence of brain metastases was found to be higher in the ALK group (24/66, 36.3 %) as compared to the EGFR group (68/220, 30.9%). Leptomeningeal spread in the ALK group was found to be less compared to the EGFR group (2/24, 8.3% as opposed to 18/68, 26.4%). Morphological heterogeneity and central necrosis in parenchymal lesions was more common in the ALK group (8/24, 33.3%) as opposed to EGFR group (2/68, 2.94%). The incidence, type and morphology of CNS lesions vary with the driver mutation status in NSCLC patients. This may have prognostic and therapeutic implications, especially in identifying patients who may benefit from upfront second or third generation TKI’s.