Presence of intra-tumoral CD61+ megakaryocytes predicts poor prognosis in non-small cell lung cancer.

Background: Lung is a reservoir for megakaryocytes (MKs). The relationship between intra-tumoral MKs and non-small cell lung cancer (NSCLC) is unknown. We investigate relationship between high intra-tumoral MKs with the recurrence of NSCLC. Methods: The tissue sections of 629 patients with resected NSCLC were stained with hematoxylin, anti-CD61, anti-CD34 and stromal cell-derived factor-1 (SDF-1). CD61+ giant cells localized in CD34+ capillaries were identified as MKs. The impact of MKs and preoperative platelet count on disease-free survival (DFS) was investigated. Results: Overall, 18.9% of patients were positive for the presence of MKs. In univariate analysis, the median DFS of the MK+ group was shorter than the median DFS of the MK-group (69.1 vs. 80.5 months; P=0.021). Multivariate analysis indicated that MKs in tumor tissue was an unfavorable prognostic factor for DFS (HR 1.351, P=0.065), the impact of which was more significant in non-squamous cell carcinoma (NSCC) (HR 1.710, P=0.008) and in patients with N0 (HR 1.883, P=0.009). Although systemic platelet count of the MK+ group was significantly higher than the MK-group (270.6x10(9) vs. 243.6x10(9)/L, P=0.007), the stratified subgroup DFS curves (P=0.003) showed that the effect of MKs on prognosis was independent of the blood platelet count. Conclusions: Our results demonstrate that CD61+ MKs in tumor tissue predict unfavorable prognosis in NSCLC.