Characteristics and prognostic value of lymphatic and blood vascular microinvasion in lung cancer.

Background: The prognostic value of vascular microinvasion (VMI) in non-small cell lung cancer (NSCLC) has been a matter of discussion in recent decades. The last T N M classification does not take VMI into account, but many points remain questionable.
Methods: A retrospective study was performed of patients undergoing operations for NSCLC during a 20-year period. Lymphatic VMI (LVMI) was classified as group (G) 1, blood VMI (BVMI) as G2, LVMI and BVMI as G3, and no VMI as G4. The demographic, pathologic, T N M characteristics, and long-term survival of each group were analyzed.
Results: A total of 3,868 patients (G1, 334; G2, 642; G3, 172; G4, 2,720), mean age 61.9 ± 10.1 years, underwent different types of resection, with complete lymphadenectomy in 88.5%. Adenocarcinomas were more frequent in G1 and G3, and squamous cell carcinomas in G2. In G2, more N1 tumors needed more extensive resections. G1 was equally distributed regardless of tumor size, but G2 prevalence increased with augmenting size. Nodules in the same lobe were significantly more frequent in LVMI than in BVMI. After exclusion of patients with R1 and R2 resections, multivariate analysis confirmed that LVMI and BVMI were independent prognostic factors as well as age, sex, type of resection, T extension, and N involvement.
Conclusions: VMI is generally associated with a poorer prognosis. LVMI is less frequent than BVMI but has lower survival rates. The benefit of adjuvant therapy in VMI patients needs to be evaluated.
(Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)