Angiogenesis is redundant for tumour growth in lymph node metastases

Angiogenesis is essential for the growth of solid tumours. As the role of angiogenesis is unclear in the pathogenesis of primary lymph node (LN) tumours, we wondered whether neoangiogenesis was important in supporting and promoting the growth of tumours in LNs.

We investigated 16 cases of squamous carcinoma involving oral cavity (n=9) and larynx/pyriform fossa (n=7), all of whom had lymph node metastases. Sections of the primary tumour, uninvolved mucosa, metastatic LN and nonmetastatic LN were double-immunostained with factor VIII-related antigen and MIB-1. Proliferating blood vessels, i.e. neoangiogenesis, was identified by coexpression of factor VIII-related antigen-stained blood vessels and MIB-1 staining of the endothelial cell nuclei. Counts were performed in an area of 4 mm2. Primary tumours (127-188.7), uninvolved mucosa (54-84.5) and metastatic LNs (123.5-167) had significantly lower vessel counts than nonmetastatic LNs (194-253.9) (P=0.003; P < 0.001; P < 0.001, respectively). With regard to neoangiogenesis, primary tumours (1.7-5) had significantly higher counts than uninvolved mucosa (0-0.4), nonmetastatic LNs (0-0.4) and metastatic LNs (0.9-2.4) (P < 0.001; P < 0.001; P=0.047, respectively).

Our data suggest that because of the rich native vascularity of lymph nodes, neoangiogenesis is redundant for the growth of metastatic tumour.