Significance of tumour vessel invasion in determining the morphology of isolated tumour cells in the pulmonary vein in non-small-cell lung cancer

The existence of clustered isolated tumour cells (ITCs) in the pulmonary vein (PV) of the lungs of patients with lung cancer has been reported to be a prognostic factor. However, the clinical-pathological characteristics related to their presence in the PV remain unclear. We analysed the surgical results and clinical-pathological findings of 130 patients who underwent surgery for non-small-cell lung cancer in regard to blood vessel invasion (BVI), serum carcinoembryonic antigen (CEA) level, maximum standardized uptake value (SUV-max), size of the solid region in computed tomography findings and pathological stage according to an ITC type, i.e. no tumour (N), singular tumour cells (S) and clustered tumour cells (C). ITCs were detected in 96 (74%) of the patients, with C observed in 43, S in 53 and N in 34. Recurrence was seen in 33 (26%) cases, 21 of which were classified as C, 9 as S and 3 as N. The disease-free survival rate was significantly worse in C cases when compared with the others (P < 0.01). The rate of C was high in cases with high serum CEA, advanced p-staging and positive BVI ratio. Furthermore, BVI positive and ITC morphology were strongly related (BVI positive; 79 in C, 40 in S, 9% in N; P < 0.01). Clustered ITCs were shown to be a prognostic indicator and strongly related to BVI. Our results suggest that determination of BVI has prognostic value, as clustered ITCs with metastatic potential are disseminated from the invaded vein.