Lymphatic microvessel density as prognostic marker in colorectal cancer

Lymph node metastases is an important prognostic indicator for disease progression and crucial for therapeutic strategies in the work-up of colorectal carcinoma. In this study, we investigated tumor lymphangiogenesis and vascular endothelial growth factor (VEGF) expression as predictive markers for the risk of lymph node metastasis and their relation to other prognostic parameters in colorectal carcinoma. Resected colorectal carcinomas from 90 patients were examined, including 30 patients without lymph node metastases, 30 with only lymph node metastases, and 30 with liver metastases. Cases were immunostained for CD31, D2-40, and VEGF. Positivity stained microvessels were counted in densely vascular/lymphatic foci (hot spots) at x 400 field (=0.17 mm2). Intensity of staining for VEGF was scored on a two-tiered scale. D2-40 lymphatic microvessel density demonstrated significant correlation with CD31 counts (20+/-9 vs 18+/-6/0.17 mm2 field, P<0.05) and VEGF expression (P<0.01). VEGF was expressed in 61/90 (67%) cases. D2-40 identified lymphatic tumor invasion in 48/90 patients, which was greater than CD31 (37/90) and hematoxylin and eosin (H&E) (31/90). There was a positive significant correlation of D2-40, CD31 counts, and VEGF expression with the presence of lymphovascular invasion and lymph node metastases (P<0.05). D2-40 lymphatic microvessel density correlated significantly with depth of invasion (pT), positive vascular pedicle lymph nodes and liver metastases (P<0.05). In conclusion, D2-40 lymphatic microvessel density showed prognostic significance with positive correlation with lymphovascular invasion, pT, and metastases to lymph nodes and liver. Immunostaining with D2-40 enhances the detection of lymphatic invasion relative to H&E staining and the endothelial marker, CD31.