125 Significance of loose tumor cells in pulmonary arteries Discussion In this multicenter retrospective study, we conducted an exploratory pilot study and a validation study in 2 separate cohorts. Our findings showed that intravascular tumor cells were present in a surprisingly high number of resected early-stage non-small cell lung cancer (NSCLC) patients. In the pilot study, individual tumor cells, small clusters of tumor cells, and/or macrophages were found in 70% of the 33 patients and in 65% of the 40 resected tumors. This finding was confirmed in the validation cohort, where intravascular tumor cells were found in 41 out of 70 (58.6%) cases. Interestingly, the presence of arterial tumor cells was associated with a seemingly better survival outcome in the pilot study and in one of the validation cohorts. Figure 3. The Kaplan-Meier curves for overall survival in the validation cohorts are shown for CK7+ tumor cells and or macrophages in lumen of the pulmonary arteries (P = .16) However, this finding was contradictory to the expected biological phenomenon. We also observed the presence of intravascular tumor cells in cases without invasive carcinoma (adenocarcinoma in situ/AIS) in both the pilot study and the validation cohort. The morphological diagnosis of tumor cells within pulmonary arteries, as we found in our study, can be distinguished from five other pathological entities, as discussed below: First, direct invasive growth through the arterial wall of tumor cells. In none of the cases in our study, direct tumor invasion in the adventitia, media, or intima layer was observed, either in the H&E stain or in the cytokeratin 7 stain. 10
RkJQdWJsaXNoZXIy MTk4NDMw