Background: Experimental studies have revealed that D2-40 is useful in identifying the presence of lymphatic invasion in various malignant neoplasms, but the clinical significance remains unclear. The purpose of this study is to assess the clinical significance of D2-40 status in completely resected non-small cell lung cancer.
Methods: A total of 215 consecutive patients with resected pathological stage I-IIIA non-small cell lung cancer were reviewed. Expression of D2-40 in tumor cells and in endothelial cells was examined immunohistochemically, and D2-40-positive lymphatic vessel density (LVD) at the tumor periphery were quantitatively evaluated.
Results: D2-40 expression on tumor cells was positive in 55 (25.6%) of 215 patients, and the incidence was significantly higher in squamous cell carcinoma (SCC) patients than in adenocarcinoma patients (48.8% vs. 8.6%, P < .001). D2-40 was also seen on lymphatic vessels in tumor tissues, and the mean number of D2-40-LVD was significantly decreased along with differentiation of tumor cells (P = .038). For all histologic types of tumors, there was no difference in the postoperative survival between higher D2-40-LVD patients and lower D2-40-LVD patients. For SCC, however, lower D2-40-LVD patients showed a significantly better survival than higher D2-40-LVD patients (5-year survival rates, 52.9% vs. 78.9%, P = .040), which was confirmed by a multivariate analyses (P = .048).
Conclusions: D2-40 expression on tumor cells was more frequently seen in SCC than in adenocarcinoma of the lung. In addition, D2-40 expression on lymphatic vessels in tumor tissues was a statistically significant prognostic factor in SCC.