116 Chapter 10 Abstract Context Loose tumor cells and tumor cell clusters can be recognized in the lumen of intratumoral pulmonary arteries of resected non-small cell lung cancer (NSCLC) specimens. It is unclear whether these should be considered tumor-emboli, and as such could predict a worsened prognosis. Objective To investigate the nature and prognostic impact of pulmonary artery intraluminal tumor cells. Design This multicenter study involved an exploratory pilot study and a validation study from 3 institutions. For the exploratory pilot, a retrospective pulmonary resection cohort of primary adenocarcinomas, diagnosed between Nov 2007 and Nov 2010, were scored for the presence of tumor cells, as well as potentially other cells in the intravascular spaces using hematoxylin-eosin (H&E), and cytokeratin 7 (CK7) stains. In the validation part, 2 retrospective cohorts of resected pulmonary adenocarcinomas, between Jan 2011 and Dec 2016, were included. Recurrence free survival (RFS), and overall survival (OS) data were collected. Results In the pilot study, CK7 positive intravascular cells, mainly tumor cells, were present in 23 out of 33 patients (70%). The 5-year OS for patients with intravascular tumor cells was 61% compared to 40% for patients without intravascular tumor cells (P=0.19). In the validation study, CK7 positive intravascular tumor cells were present in 41 out of 70 patients (58.6 %). The 5-years RFS for patients with intravascular tumor cells was 80.0% compared to 80.6% in patients without intravascular tumor cells (P=0.52). The 5-year OS rates were respectively 82.8% and 71.6% % (P=0.16). Conclusion Loose tumor cells in pulmonary arterial lumina were found in most NSCLC resection specimens and were not associated with a worse RFS or OS. Therefore, most probably they represent an artifact.
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