Prevalence, correlations and prognostic significance of the presence of microscopic vascular invasion following complete resection of Stage I non-small cell carcinoma: an underestimated factor?

Objective: The significance of microscopic invasion of blood vessels (Microscopic Vascular Invasion, MVI) in patients with non-small cell lung carcinoma (NSCLC) remains controversial. The aim of this study was toevaluate prevalence, correlations and the prognostic significance of MVI in patients following complete resection of Stage I NSCLC. Methods: From 1/1998 to 10/2008 1521 patients received resection for NSCLC at our Institution, of whom 737 were at pathological Stage I after surgery. There were 323 adenocarcinomas (ADK) (44%), 322 squamous cell carcinomas (SCC) (44%), 53 bronchioloalveolar carcinomas (BAC) (7%), 29 large cell anaplastic carcinomas (LCC) (4%). Histologic grading was: 114 G1 (15%), 279 G2 (38%) and 344 G3 (47%). Mean tumour dimension was 36 mm. MVI was ascertained using routine histopathological workup. Immunohistochemical staining with antibody anti-CD34 was done to evaluate blood vessels on a selective basis. Prevalence differences, logistic regression and survival analysis were used for analysis. Results: MVI was observed in 228 patients (31%). Prevalence was significantly higher in ADK (131/323, 41%) than in SCC (80/322, 25%, p0.002). A significant correlation was found between the presence of MVI and ADK (OR 0.8, 95% CI 0.7-0.9) and increased tumour dimension (OR 1.1, 95% CI 1.01-1.24). Univariate survival analysis indicates that the presence of MVI was associated with a significantly reduced 5-year survival overall (65% vs. 52%, p0.0003) and in ADK (68% vs. 54%, p0.0002) but not in SCC (58% vs. 49%, p0.25). In a multivariate survival analysis, the presence of MVI was a significant indicator of poor survival overall (HR 1.61, 95% CI 1.30 –2.15) and in ADK (HR 2.02, 95% CI 1.36 –3-02). Conclusions: The finding of MVI in completely resected Stage I NSCLC is not infrequent. MVI is strongly correlated with adenocarcinoma histotype and increased tumour dimensions. The presence of MVI is an independent negative prognostic factor, which is particularly significant in adenocarcinomas. The use of adjuvant chemotherapy might be taken into consideration in these patients. Disclosure: All authors have declared no conflicts of interest