Circulating tumor cells and microemboli can differentiate malignant and benign pulmonary lesions

The presence of circulating tumor cells (CTC) or microemboli (CTM) in the peripheral blood can theoretically anticipate malignancy of solid lesions in a variety of organs. We aimed to preliminarily assess this capability in patients with pulmonary lesions of suspected malignant nature. We used a cell-size filtration method (ScreenCell) and cytomorphometric criteria to detect CTC/CTM in a 3 mL sample of peripheral blood that was taken just before diagnostic percutaneous CT-guided fine needle aspiration (FNA) or core biopsy of the suspicious lung lesion. At least one CTC/CTM was found in 47 of 67 (70%) patients with final diagnoses of lung malignancy and in none of 8 patients with benign pulmonary nodules. In particular they were detected in 38 (69%) of 55 primary lung cancers and in 9 (75%) of 12 lung metastases from extra-pulmonary cancers. Sensitivity of CTC/CTM presence for malignancy was 70.1% (95%CI: 56.9-83.1%), specificity 100%, positive predictive value 100% and negative predictive value 28.6% (95%CI: 11.9-45.3%). Remarkably, the presence of CTC/CTM anticipated the diagnosis of primary lung cancer in 3 of 5 patients with non-diagnostic or inconclusive results of FNA or core biopsy, whereas CTC/CTM were not observed in 1 patient with sarcoidosis and 1 with amarthocondroma. These results suggest that presently, due to the low sensitivity, the search of CTC/CTM cannot replace CT guided percutaneous FNA or core biopsy in the diagnostic work-up of patients with suspicious malignant lung lesions. However, the high specificity may as yet indicate a role in cases with non-diagnostic or inconclusive FNA or core biopsy results that warrants to be further investigated.