In NSCLC, a threshold of 15% ALK‐rearranged cells is used when determining whether a tumor is ALK‐positive.49 However, no such thresholds currently exist for CTCs.50 While our data are consistent with a number of studies having reported on the presence of ALK rearrangement in CTCs,49, 50 the spatial distribution of the ALK signal for CTCs has not been reported. The gene discussed is ALK; the disease is non-small cell lung carcinoma.