Background: Vascular endothelial growth factor (VEGF) plays an important role in tumor growth and metastasis. We investigated the prognostic significance of VEGF overexpression, intratumoral microvessel density (MVD), and angiolymphatic invasion in stage Ia-b non-small cell lung cancer (NSCLC).
Methods: Eighty-five patients undergoing complete surgical resection of pathologic stage Ia-b NSCLC were evaluated. The mean and median clinical follow-up were 37.1 and 39.0 months (range, 30-44 months), respectively. Paraffin-embedded tumor specimens were stained with VEGF and CD31 (a specific endothelial marker) using immunohistochemical methods. VEGF staining was evaluated, by combining both percentage of positive tumor cells and staining intensity, as low (negative and < 20% of tumor cells showing weak positivity), or high (> 20% of tumor cells showing strong positivity). CD31 staining was expressed as MVD per high power field at 400x magnification. Angiolymphatic invasion was expressed as either presence or absence.
Results: Low VEGF expression was seen in 25 (29%) patients, and high VEGF expression was seen in 60 (71%) patients. The survival rate in patients with low VEGF expression was significantly higher (80%) than that in those with high VEGF expression (48%, P = .018). The mean MVD in the low VEGF group was 23.7 +/- 5.7 vs. 34.4 +/- 9.3 in the high VEGF group (P = .001). Patients with high MVD also had a significantly lower survival rate than did those with low MVD count (46% vs. 73%, P = .0053). Age, sex, tumor type, and tumor differentiation were not found to be associated with overall survival. The presence of angiolymphatic invasion and T2 stage (i.e., tumor size > 3 cm) were associated with decreased survival. High VEGF expression, tumor size, and angiolymphatic invasion emerged as three independent factors predicting worsening prognosis using multivariate analysis.
Conclusion: High VEGF expression within stage I NSCLC is closely associated with high intratumoral angiogenesis and poor prognosis. Immunohistochemical evaluation of T stage and VEGF expression along with examination of angiolymphatic invasion perioperatively may aid in predicting prognosis. Adjuvant therapies aimed at retarding tumor angiogenesis may be considered for stage I NSCLC patients with high VEGF levels.