COX-2 expression correlates with VEGF-C and lymph node metastases in patients with head and neck squamous cell carcinoma.

Recent observations suggest an implication of the cyclooxygenase-2 (COX-2) in tumor lymphangiogenesis through an upregulation of vascular endothelial growth factor-C expression. It is unknown whether this mechanism also acts in squamous cell carcinoma of the head and neck region. We performed a retrospective study of 70 patients with head and neck squamous cell carcinoma in order to investigate whether COX-2 immunohistochemical expression correlates with vascular endothelial growth factor-C expression. We also examined the association of the expression of these molecules with clinicopathologic parameters (especially lymph node status) and outcome for these patients. We performed immunostaining on formalin-fixed, paraffin-embedded tissue sections by the routine streptavidin-biotin peroxidase labeled procedure. Increased cyclooxygenase-2 expression was observed in 30 of the 68 tumor samples (44%), while high vascular endothelial growth factor-C expression occurred in 26 of the 68 tumor samples (38%). High expression of the two proteins was correlated with the presence of lymph node metastasis at the time of diagnosis, and the observed association was even stronger when there was overexpression for both the antibodies (P<0.001). High expression of vascular endothelial growth factor-C, but not of COX-2 was correlated with increased mortality in patients with oral-larynx squamous cell carcinoma. When multivariate Cox regression model was applied, the presence of lymph node metastasis at the time of diagnosis, combined with overexpression of both the antibodies, was the only independent prognostic factor for mortality of these patients. Our results suggest that a lymphangiogenic pathway, in which COX-2 overexpression stimulates vascular endothelial growth factor-C upregulation, probably exists in head and neck squamous cell carcinoma. Also, the predictive ability for mortality of regional lymph node metastasis can be improved with the combined evaluation of the immunohistochemical expression of these two proteins.