Background: Circulating tumor cells in peripheral blood (CTC) is a potential surrogate of distant metastasis, which is the critical factor influencing decision making regarding therapy and prognosis of primary lung cancer patients. After our preliminary study showing that CTCs were detected in peripheral blood in 29.4% of resectable lung cancer patients, we conducted a prospective study on CTC in pulmonary vein (PV) blood because tumor cells apart from the primary tumor may circulate after passing through the drainage PV.
Methods: A total of 30 consecutive lung cancer patients who underwent thoracotomy were included. The CTCs in peripheral blood and in PV blood from the primary tumor site were quantitatively examined with the CellSearch system, and the numbers of CTCs per 7.5 mL peripheral and PV blood in each patient were represented as periCTC count and pvCTC count, respectively.
Results: Circulating tumor cell was detected in peripheral blood in 5 patients (16.7%; the periCTC count was 1 in 2 patients; and 2, 3, and 16 in 1 patient each), and the incidence of positive periCTC was higher in squamous carcinoma patients than in adenocarcinoma patients (p = 0.028). Circulating tumor cell was detected in PV blood in most patients (29 of 30, 96.7%), and the mean and median pvCTC counts were 1,195 and 81, respectively (range, 0 to 10,034). There was no significant correlation between pvCTC count and any other patient characteristic, including periCTC count.
Conclusions: In resectable lung cancer, CTC was positive in peripheral blood of some patients and in PV blood of most patients. A long-term follow-up study to clarify the clinical significance of pvCTC status is warranted.