2022 World Conference on Lung Cancer (ePosters)-EP03.01-005. Clinicopathological Features of ROS1-rearranged Adenocarcinomas: A Single Institutional Experience Spanning Four Years From India

EP03.01-005. Clinicopathological Features of ROS1-rearranged Adenocarcinomas: A Single Institutional Experience Spanning Four Years From India

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This document describes the clinicopathological features of ROS1-rearranged (ROS1-R) adenocarcinomas, a relatively rare but treatable molecular subgroup of non-small cell lung carcinomas. The prevalence of ROS1-R adenocarcinomas is estimated to be around 1% in Western literature, with slightly higher rates in Asian countries. In these adenocarcinomas, ROS1 fuses with various fusion partners to create a chimeric protein with oncogenic tyrosine kinase activity. The sensitivity of ROS1 immunohistochemistry for detecting ROS1 rearrangements is high, but confirmation using molecular methods is necessary due to the lack of specificity.<br /><br />The study aimed to analyze the clinicopathological features of ROS1-R adenocarcinomas diagnosed in a specific institution by combining immunohistochemistry and fluorescence-in-situ hybridization. The study design was ambispective, including both retrospective and prospective data from January 2018 to April 2022. Patients with advanced stage non-squamous non-small cell lung carcinoma were screened for epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements. ROS1-R screening was performed using immunohistochemistry and confirmed with fluorescence-in-situ hybridization.<br /><br />The results showed that ROS1-R was identified in 1.4% of all lung adenocarcinomas during the study duration. Patients with ROS1-R adenocarcinomas had a median age of 48 years and a male-to-female ratio of 9:8. These adenocarcinomas were predominantly classified as adenocarcinoma, non-small cell lung carcinoma not otherwise specified (NOS). TTF-1 expression was positive in all cases. Metastatic sites included the bone, liver, and thyroid. The recommended treatment was chemotherapy or tyrosine kinase inhibitors, and the median progression-free survival on tyrosine kinase inhibitors was 166 days.<br /><br />In conclusion, ROS1-R adenocarcinomas represent a small percentage of lung adenocarcinomas and are associated with younger age at presentation and frequent bony metastases. The study suggests that a prospective screening approach using immunohistochemistry followed by confirmation with fluorescence-in-situ hybridization is feasible for diagnosing ROS1-R adenocarcinomas. It also notes that non-specific ROS1 immunopositivity can occur in EGFR mutant and ALK-rearranged adenocarcinomas.

Asset Subtitle

Aruna Nambirajan

Meta Tag

Speaker Aruna Nambirajan

Topic Epidemiology

Keywords

ROS1-rearranged adenocarcinomas

non-small cell lung carcinomas

oncogenic tyrosine kinase activity

immunohistochemistry

molecular methods

epidermal growth factor receptor mutations

anaplastic lymphoma kinase rearrangements

fluorescence-in-situ hybridization

metastatic sites

tyrosine kinase inhibitors