Clinicopathological characteristics and survival of ALK, ROS1 and RET rearrangements in non-adenocarcinoma non-small cell lung cancer patients

Abstract

Background: ALK, ROS1 and RET rearrangements represent 3 most frequent fusion genes in non-small cell lung cancer (NSCLC). Rearrangements of these 3 genes exist predominantly in lung adenocarcinoma while rarely in non-adenocarcinoma. Our objective was to explore the frequency, clinicopathological characteristics and survival of ALK, ROS1 and RET rearrangements in non-adenocarcinoma NSCLC patients. Methods: ALK, ROS1 and RET rearrangements were screened by reverse transcriptase polymerase chain reaction (RT-PCR) in patients with completely resected non-adenocarcinoma NSCLC. All positive samples were confirmed with fluorescence in situ hybridization (FISH). Survival analysis was performed with Kaplan-Meier method and log-rank for comparison. Results: A total of 385 patients underwent complete resection, including squamous cell carcinoma (n = 245), adenosquamous carcinoma (n = 85) and large cell carcinoma (n = 55). Twelve of them were identified as harboring fusion genes, including ALK (n = 7), ROS1 (n = 3) and RET (n = 2) rearrangements. The fusion frequencies of adenosquamous, squamous cell and large cell carcinomas were 8.2%, 1.6% and 1.8% respectively. Their median age was 49.5 y and 3 of them had a smoking history. No survival difference existed between fusion gene positive and negative patients (36.7 vs.50.2 months, P = 0.21). Conclusion: The frequencies of ALK, ROS1 and RET rearrangements are low in non-adenocarcinoma NSCLC patients. And their clinical characteristics are similar to those in lung adenocarcinoma. Fusions of the above 3 genes are not prognostic factor for non-adnocarcinoma NSCLC patients.