ALK and non-small cell lung carcinoma: Furthermore, a recent retrospective study testing 3774 samples from NSCLC patients (tested for EGFR, ALK, ROS1, K-RAS and BRAF) observed that only 1.7% harboured mutations in two or three genes, and among these patients, EGFR/K-RAS was the most frequent coalteration (31.7%), followed by ALK/K-RAS (17.5%) [175].