Recurrences in stage II rectal carcinoma after curative resection alone: from the viewpoint of angiogenesis

BACKGROUND Angiogenesis plays a pivotal role in malignant tumor progression. The count of blood microvessels of the tumor has been recognized as an indicator of malignant potential of the tumors and provides the ability to predict tumors recurrence. The role endoglin in the Dukes B rectal cancer is still unexplored. The aims of this study were to examine immunohistochemical expression of endoglin in resected rectal cancer and investigate the relationship of tumor recurrence and other clinicopathological variables to the endoglin-assessed microvessel density of the tumor tissue and distal resection margins. METHODS The study included 95 primary rectal adenocarcinomas, corresponding to 95 distal and 95 proximal resection margin specimens from surgical resection samples. Tumor specimens were paraffin embedded, and immunohistochemical staining for the CD105 endothelial antigen was performed to count CD105-MVD. For exact measurement of the CD105-MVD used, a computer-integrated system Alphelys Spot Browser 2 was used. RESULTS The MVD was significantly higher in the tumor samples compared with the distal resection margins (p < 0.0001) and the proximal resection margins (p < 0.0001). There was no significant difference in the MVD between distal and proximal resection margins (p = 0.147). The type of surgical resection was a significant factor for determining the recurrence of tumors (p = 0.0104). There was no significant effect of patients' age, gender, tumor location, grade of differentiation, histological tumor type, and the size and depth of tumor invasion on the recurrence of the tumor. The recurrence rate was significantly higher in the low CD105-MVD group of patients than in the high CD105-MVD group of patients (log rank test, p = 0.0406). Result of the multivariate analysis showed that the type of surgery (p = 0.0086), MVD tumors (p = 0.0385), and MVD of proximal resection margin (p = 0.0218) were the independent prognostic factors for the recurrent tumors. CONCLUSIONS CD105-assessed MVD could help to identify patients with more aggressive disease and increased risk of developing tumor recurrence after surgical treatment in stage II rectal cancer (RC).