Role of hypoxia and angiogenesis in oral cancer (OSCC) metastasis

Metastatic OSCC is a life threatening disease and tumor hypoxia in OSCC is associated with poor prognosis. Objective: To determine the OSCC microvessel (MVD) and lymphatic vessel (LVD) densities and correlate them with intratumoral hypoxia and lymph node metastasis. Methods: OSCC with (n=13) and without (n=12) LN metastasis were examined in this study. Primary tumors were immunohistochemially stained using the antibodies against carbonic anhydrase 9 (CA9), CD34, LYVE-1 and D2-40. Hypoxia levels, the MVD (CD34) and intra- and peritumoral LVD (LYVE-1; D2-40) scores were determined according to the published reports. Statistical analyses were done using the SPSS software and p-values < 0.05 were considered statistically significant. Results: Hypoxic areas in tumors were identified by strong membranous CA9 positivity in tumors cells which are zonal in distribution and often found adjacent to necrotic areas. The hypoxia score for all cases ranged from 0.05 to 1.4 (median = 0.2; mean ± SD = 0.38 ± 0.38). Larger tumors (T3&T4) revealed significantly higher (p=0.003) mean hypoxia level than the T1/T2 tumors. Metastatic OSCC had significantly higher (p = 0.013) MVD (mean ± SD = 36.6 ± 17.6) than non-metastatic OSCC (mean ± SD = 21.8 ± 17.6). The median intratumoral and peritumoral LVD scores obtained with D2-40 antibody for all tumors were 1.3 and 2, respectively. Only peritumoral lymph vessels were stained with LYVE-1 antibody. The intratumoral LVD score was significantly higher (p=0.016) in metastatic OSCC than non-metastatic OSCC. There was no significant association between hypoxia levels and metastatic status or histology grade MVD or LVD. Conclusion: D2-40 is a more sensitive marker than LYVE-1 for intratumoral lymph vessels. There is a significant association between increased intratumoral MVD, LVD and LN metastasis in OSCC. Our data suggest that tumor hypoxia is not the primary mediator for increased angiogenesis and lymphangiogenesis related OSCC metastasis.