Single cell RNA-seq data showed that circulating tumor cell (CSF-CTCs) from seven NSCLC-LM patients (P1, P2, P4, P6, P7, P-A and P-D) had higher level of WFDC2 mRNA (encoding HE4) than CSF immune cells (Figures 1A, B). Here, WFDC2 is linked to non-small cell lung carcinoma.