ALK and adenocarcinoma: The frequency of ALK rearrangement ranges from 3% to 7% in unselected NSCLC patients, which could reach to 13% ∼ 18%, if the patient population is selected according to specific clinicopathologic characteristics, especially in young, never-or light smokers with adenocarcinoma [4], [5], [6], [7], [8], [9].