117 Significance of loose tumor cells in pulmonary arteries Introduction Lung cancer is associated with a high incidence of pulmonary embolism, caused by thrombotic emboli, as a paraneoplastic phenomenon, but also caused by real tumoremboli176. In general, pulmonary tumor embolism can be categorized by size, into large, proximal emboli and smaller emboli in the microvasculature. Tumor-emboli occurring in large branches of the pulmonary artery, are associated with an acute deterioration of clinical performance. Pulmonary tumor embolism localized in smaller branches of the pulmonary arteries is described by two different entities: pulmonary tumor microembolism and pulmonary tumor thrombotic microangiopathy177–179. These two conditions are likely to represent a spectrum of the same disease and may be associated with pulmonary hypertension177,180. Although pulmonary tumor-emboli are a known specific entity and can be diagnosed in tumor biopsies or tumor resection specimen, it is unclear whether all intravascular tumor cells in pathology slides can be considered tumor-emboli. In our experience, a substantial incidence of tumor cells can be recognized in the lumen of intra-tumoral pulmonary arteries in many resected non-small cell lung cancer (NSCLC) specimens, albeit with a morphological aspect, distinct from regular tumor-emboli. We hypothesized that these ‘common’ loose intravascular tumor cells may be caused by technical artifacts through displacement in the preparation process of the slides. Therefore, we aimed to investigate the prognostic impact of these intravascular tumor cells and to substantiate the claim that these intravascular tumor cells may be caused by iatrogenic artifacts. Materials and methods Design This study involved an exploratory pilot study and a validation study. While studying a previously described cohort of patients with adenocarcinoma of the lung (diagnosed on biopsies and 195 resections from different institutes), between November 2007 and November 2010181, we observed the presence of intravascular tumor cells in a high number of cases. We conducted an exploratory pilot study on a subset of this cohort (n=33) to confirm our findings. The selection of participants was based on the availability of slides and paraffin blocks for additional staining of resections performed at the Vrije Universiteit Medical Center (VUmc) in Amsterdam, the Netherlands. Additionally, participants were included in the study based on the availability of clinical follow-up. Hematoxylin and eosin (H&E) stained slides were retrieved from the archive and for each resected tumor 1 or 2 most representative tumor slides were selected. Cytokeratin 7 (CK7) staining was performed as described below on the sections of the same paraffin block(s). 10
RkJQdWJsaXNoZXIy MTk4NDMw