OBJECTIVETo investigate the correlation of vascular endothelial growth factor D (VEGF-D) expression, microlymphatic density (MLD) and microvessel density (MVD) levels with the development and metastasis of rectal cancer.

METHODSEighty specimens from resected middle-lower rectal cancer diagnosed by pathology were examined by immunohistochemistry for VEGF-D,MLD and MVD. Simultaneously, 40 biopsy specimens from rectal polyps and 80 specimens from normal rectal tissue were examined as controls. Correlation between the expression of above three factors and the tumor size, gross morphology, histological type, metastasis, differentiation grade, infiltration depth, Dukes stage, lymph node metastasis and long-distance metastasis before operation were investigated with Spearman method.

RESULTS(1) Positive expression rate of VEGF-D was 55 % (44/80) in rectal cancer, and zero in rectal polyps and normal rectal tissues. The expression of VEGF-D in rectal cancer was significantly higher than that in rectal polyps and normal rectal tissues(P<0.05). MLD was significantly higher in rectal cancer (2.80+/-1.31) than that in rectal polyps (0.50+/-0.72) and normal rectal tissues(0.25+/-0.44)(P<0.05).Meanwhile MVD was significantly higher in rectal cancer (80.10+/-23.18) than that in rectal polyps (27.00+/-11.01) and normal rectal tissues (10.45+/-5.34) (P<0.05). (2) VEGF-D, MLD and MVD were positively correlated with lymph node metastasis and long-distance metastasis before operation (P<0.05). (3) VEGF-D was positively correlated with MLD (P<0.05) and MLD was positively correlated with MVD as well(P<0.05).

CONCLUSIONSLymphangiogenesis exists in rectal cancer tissues. VEGF-D and MLD can be used as good predictors of lymphangiogenesis and they are the important factors affecting biological behavior of rectal cancer. Lymphangiogenesis and angiogenesis may have a cooperative function in the development of rectal cancer.