CK+/Ki67+, CK+/M30+ and CK+/Vim+ CTCs represent distinct subpopulations of CTCs in patients with SCLC, can be detected even in the absence of detectable CTCs by CellSearch; CK+/Ki67+ and CK+/Vim+ CTCs are associated with unfavorable clinical outcome. Here, VIM is linked to small cell lung carcinoma.