Lymphatic invasion is a significant indicator of poor patient prognosis in lung squamous cell carcinoma.

Pathological stage is the most important prognostic factor in patients with lung cancer, and is defined according to the tumor node metastasis classification system. The present study aimed to investigate the clinicopathological significance of lymphatic invasion in 103 patients who underwent surgical resection of lung squamous cell carcinoma (SqCC). The patients were divided into two groups, according to the degree of lymphatic invasion: Those with no or mild lymphatic invasion (ly0‑1) and those with moderate or severe lymphatic invasion (ly2‑3). Ly2‑3 was associated with tumor size (P=0.028), lymph node metastasis (P<0.001), venous invasion (P=0.001) and histological differentiation (P=0.047). Statistical analysis using the Kaplan‑Meier method and the log‑rank test indicated that overall survival was significantly reduced in patients with ly2‑3 compared with those with ly0‑1 (P<0.001). Multivariate analysis identified ly2‑3 as an independent predictor of mortality (hazard ratio, 2.580; 95% confidence interval, 1.376‑4.839). In conclusion, moderate or severe lymphatic invasion (ly2‑3) indicated a high malignant potential and may be considered an independent predictor of poor prognosis in patients with SqCC of the lung.