Vascular Invasion Predicts Recurrence in Stage IA2-IB Lung Adenocarcinoma but not Squamous Cell Carcinoma.

Background: Lymphovascular invasion (LVI) is an adverse prognostic feature in resected stage I non-small cell lung cancer (NSCLC); however, it is unclear if the prognostic significance applies to both lung adenocarcinoma (LUAD) and squamous cell carcinoma (LUSC).

Materials And Methods: A retrospective review of H&E-stained slides from surgically resected AJCC 8 ed. stage IA2-IB LUAD (n = 344) and LUSC (n = 102) from two institutions was performed. LVI was defined as either lymphatic (LI) or vascular (VI) invasion. Outcomes were assessed by 5-year recurrence-free survival (RFS) estimates using the Kaplan-Meier method.

Results: The cohorts of LUAD and LUSC showed no significant differences in 5-year RFS (81% each), stage, age, race, or surgical procedure. The presence of LVI, VI, and LI was predictive of 5-year RFS for LUAD (LVI + 71% vs. LVI - 92%, P < 0.001; VI + 64% vs. VI - 90%, P < 0.001; LI + 75% vs. LI - 84%, P = 0.030) but not LUSC (LVI + 84% vs. LVI - 79%, P = 0.740; VI + 83% vs. VI- 80%, P = 0.852; LI + 84% vs. LI - 81%, P = 0.757). Among LUAD with LVI, VI was a stronger predictor of 5-year RFS than the remaining subset of VI-LI + tumors (64% vs. 87%, P = 004). Subset analysis of LI among LUAD stratified by VI showed no significant prognostic advantage to adding LI for risk stratification (VI-LI + 87% vs. VI-LI - 92%, P = 0.347 & VI+LI + 62% vs. VI + LI- 66%, P = 0.422). VI was present in 36% of LUAD.

Conclusion: Vascular invasion is a strong predictor of recurrence in stage IA2-IB LUAD but not in LUSC. Adjuvant therapy trials should be directed at this subgroup.