Detection of ROS 1 translocation in lung adenocarcinoma by IHC , FISH and RT-PCR and its clinicopathologic features

Recently, the translocation of c-ros oncogene 1, receptor tyrosine kinase gene (ROS1) has been demonstrated in lung adenocarcinoma (ADC), but the rate of this translocation is relatively low (~1%). In the present study, data from 473 patients with lung ADC were collected from archived records in the Department of Pathology, Sichuan Academy of Medical Sciences & Sichuan Provincial People’s Hospital, China. The original data were obtained between July 2007 and April 2014. ROS1 translocations were confirmed in 11 patients (2.32%) by screening with immunohistochemistry (IHC) staining and verification with reverse transcription-polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH). The sex ratio was significantly different in the ROS1-translocated group compared with the non-ROS1-translocated group, with the former having a higher proportion of females (P = 0.032). The 11 patients harboring ROS1 translocations had no history of smoking (100%). Histomorphological analysis revealed that the tumors were mostly papillary, with micropapillary components being observed in the majority of positive cases (7/11, 64%). Fewer cases exhibited extracellular mucus secretion and signet-ring components. ROS1 translocations represent another unique molecular subtype of lung ADC with clinical significance. The incidence of ROS1 translocation in lung ADC patients is 2.32%. IHC staining can be used to screen for ROS1 translocations, and positive cases should be verified by FISH or RT-PCR.