Lymph node metastases outside tumor-bearing lobes and/or segments in non-small cell lung cancer

Hilar and lung lymph node metastases (N1) are defined as ipsilateral bronchial and intrapulmonary lymph nodes. However, the cleaning standards for ipsilateral bronchial lymph nodes in different lobes and segments within the same lobe in segmentectomy are not clearly defined.

Sixty-six patients undergoing pulmonary resection for the treatment of lung cancer were evaluated. Intraoperatively visible non-tumor-bearing lobe (NTBL) and post-operatively non-tumor-bearing segment (NTBS) lymph nodes were removed and analyzed. The associations between the NTBL LNs and clinicopathological characteristics were analyzed.

Non-tumor-bearing lobe LNs metastases were found in 8 (12.1%) of the 66 patients, NTBS LNs metastasis were not found (0/13). The presence of NTBL metastases was significantly associated with age (<60 years vs. ≥60 years, P = 0.037), differentiation (Grade 1 well differentiated vs. Grade 2 moderately differentiated vs. Grade 3 poorly differentiated, P = 0.012), CAT-scan-findings of Mediastinal and hilar lymph nodes metastasis (node-positive vs. node-negative, P = 0.022), pN stage (N0 vs. N1 vs. N2, P = 0.003) and p stage (I vs. II vs. III, P = 0.009). Multivariate logistic analysis showed that tumor differentiation (P = 0.048, HR 6.229; 95% CI 1.016-38.181) and pN (P = 0.024, HR 5.099; 95% CI 1.245-20.878) were statistically significant predictors.

Lobar lymph node metastasis of NTBL occurs frequently in patients with NSCLC, but lymph node metastases in NTBS LNs are rare. Advanced age, poorly differentiated and N1 and N2 status of CAT-scan-findings were independent risk factors for the involvement of the NTBL lobar lymph nodes. Although lymph node metastases in NTBS are rare, further investigation of the need to dissect is required.