Tumor-associated macrophages and angiogenesis in early stage esophageal squamous cell carcinoma

The association between angiogenesis and tumor-associated macrophages (TAMs) is unclear. Mononuclear cell infiltration was reported to induce angiogenesis in early stage esophageal squamous cell carcinoma (ESCC). The study materials included 14 samples of normal squamous epithelium, 11 samples of low-grade intraepithelial neoplasia, and 64 samples of superficial esophageal cancer (M1 and M2 cancer 27; M3 or deeper cancer 37). We assessed microvessel density (MVD) using CD34 and CD105 immunostaining and monocyte count (MC) using CD68 and CD163 immunostaining in relation to the histological type or grade of mononuclear cell infiltration, as well as the correlation between MVD and MC. MVD and MC increased in accordance with histological type, and the differences were significant (P < 0.001). MVD and MC were significantly higher in M1 and M2 lesions than in normal squamous epithelium (P < 0.05). MVD (CD34 and CD105) and MC (CD68 and CD163) were significantly correlated with the degree of mononuclear cell infiltration (P < 0.001), and there was a strong correlation between MC assessed using CD68 and MC assessed using CD163 (rS = 0.93, P < 0.001). The CD163/CD68 ratio did not differ significantly according to histological type. There was a significant correlation between MVD assessed using CD105 and MC assessed using CD68 (rS = 0.69, P < 0.001) and CD163 (rS = 0.67, P < 0.001). MVD assessed using CD34 was also significantly correlated with MC assessed using both CD68 (rS = 0.59, P < 0.001) and CD163 (rS = 0.57, P < 0.001). The number of TAMs is significantly associated with the development of neovasculature in the early stage of ESCC progression.