To further investigate our hypothesis regarding the limitations of EpCAM‐dependent CTC enrichment systems, such as CellMagTM, in lung cancer; we conducted spike‐in experiments with EpCAMmoderate A549 cells and EpCAMlow (considered as EpCAM‐negative) H1299 cells using the CellMagTM and Parsortix® PR1 in‐cassette staining systems. The gene discussed is EPCAM; the disease is lung cancer.