Programmed death ligand‐1 expression and occult lymph node metastasis in non‐small cell lung cancer

BACKGROUND: Identifying the preoperative risk factors for lymph node upstaging could contribute to the development of individualized perioperative treatment for patients with non‐small cell lung cancer (NSCLC). The current study aimed to evaluate the risk factors for lymph node upstaging, including gene mutation and programmed death ligand‐1 expression in patients with resectable NSCLC. METHODS: Data on the clinicopathological characteristics of patients who underwent lobectomy for clinical N0 NSCLC at our institution were collected. The clinicopathological findings of the pathological N0 and lymph node upstaging groups were then analyzed. Univariate and multivariate analyses were performed to examine the predictive factors for nodal upstaging. RESULTS: Of 291 patients, 40 had postoperative nodal upstaging (n = 25, N1; n = 15, N2). Large tumor size and high maximum standardized uptake value were significantly associated with nodal upstaging. The nodal upstaging group had a higher proportion of patients with solid adenocarcinoma and lymphatic, vascular, and pleural invasion than the pathological N0 group. Further, the nodal upstaging group had a higher proportion of patients with positive programmed death ligand‐1 expression than the pathological N0 group. Univariate and multivariate analyses showed that tumor size and positive programmed death ligand‐1 expression were associated with nodal upstaging. CONCLUSION: The appropriate therapeutic strategy including preoperative treatment and resection should be cautiously considered preoperatively in patients with clinical N0 NSCLC who have large tumors and positive programmed death ligand‐1 expression.