Abstract
Rearrangements to the c-ros oncogene 1, receptor tyrosine kinase (ROS1) gene are reported in 1-2% of lung adenocarcinomas. These rearrangements are associated with a response to the small-molecule tyrosine kinase inhibitor crizotinib. ROS1 rearrangements can be detected using fluorescence in situ hybridization (FISH), which is considered the gold standard technique in detecting ROS1 rearrangements, and determining whether a patient would respond well to crizotinib treatment. However, FISH is an expensive and time-consuming assay, requiring specialized microscopy equipment and some level of technical expertise. The present report describes the case of a patient with advanced lung adenocarcinoma, who was identified to be negative for ROS-1 rearrangements by FISH, but positive by immunohistochemistry (IHC). The health of the patient improved following treatment with crizotinib. These results indicate that IHC assay could be an alternative option for the detection of ROS1 gene rearrangements.