VEGF-C and lymphatic vessel density in oral squamous cell carcinoma: association with occult lymph node metastases and patients' prognosis

Abstract

The metastatic dissemination of head and neck squamous cell carcinoma (HNSCC) to neck lymph nodes occurs rather through the lymphatic system. Furthermore, it has long been established that the presence of lymph node metastasis (pN+), verified through histopathological analysis, is the most important prognostic factor to the patients with HNSCC. Recent studies reported that the vascular endothelial growth factor C (VEGF-C) may directly induces lymphangiogenesis and dilatation of lymphatic vessels in solid tumors of different sites. However, the VEGF-C and its correlation with the lymphatic vessel density has not been frequently studied in oral squamous cell carcinoma (OSCC). The aim of this study is: (1) to evaluate the peri and intratumoral lymphatic vessel density using podoplanin antibody; (2) to correlate the lymphatic vessel density and the VEGF-C expression, as described previously by Faustino, S.E.S (2007); (3) to verify the lymphatic vessel density and its correlation with the occurrence of occult metastasis in neck lymph nodes and with the patients’ prognosis with OSCC. A total of 87 cases of surgically excised primary oral squamous cell carcinoma with clinical stages I and II (located in tongue and floor of the mouth) from the files of Head and Neck Surgery and Otohinolaryngology Department of the A. C. Camargo Cancer Hospital, São Paulo, Brazil, from 1968 to 2001, studied previously by Faustino, S.E.S (2007), will be analyzed. Clinical information regarding the gender, age, race, tobacco and alcohol abuse, localization, stage by the TNM/UICC, treatment, lymph nodes involvement, local and cervical recurrences, distant metastasis and second primary tumors were obtained from the patients’ files. In addition, the immunohistochemical study will be performed on paraffin sections of OSCC with monoclonal podoplanin (specific for lymphatic vessel) using a standard streptavidin-biotin-peroxidase technique. The peri- and intratumoral lymphatic vessel density immunostained with podoplanin will be analysed using a camera attached to a light microscope and a specific computer image software. The correlation among the lymphatic vessel density on the OSCC and: (1) VEGF-C expression; (2) clinical and microscopic variables; (3) histopathological malignancy grading and (4) occurrence of occult lymph node metastases will be obtained by chi-square test or Fisher exact test. The 5 and 10-year survival rates will be calculated by the Kaplan-Meier method and compared by log-rank test. P values less than 0.05 will be considered statistically significant. (AU)