In our laboratory, by using RET-FISH as a screening method for RET-rearrangement detection on 784 EGFR-, KRAS-, ALK- and ROS1-negative NSCLC samples, we found 32 samples to be positive by FISH with the previously mentioned positivity criteria, making our study the second largest study of RET-FISH positive samples to date after the study by Kim et al.32 This evidence concerns the gene KRAS and non-small cell lung carcinoma.