EGFR and non-small cell lung carcinoma: Further, in patients with advanced, EGFR-positive NSCLC, high level of FR+CTC (≥ 17 FU/3 ml) prior to first-line EGFR tyrosine kinase inhibitor treatment was associated with poorer prognosis compared to lower baseline level of FR+CTC (< 17 FU/3 ml) (18).