Non-adjacent interlobar lymph node metastasis distant from small-sized peripheral non-small cell lung cancer

Purpose The optimal extent of lymph node dissection (LND) during segmentectomy is unclear. During segmentectomy, it is more challenging to dissect the non-adjacent interlobar lymph node (non-aiLN) away from the primary tumor than to dissect the adjacent interlobar lymph node (aiLN), as injury to the preserved parenchyma and bronchus may occur. We examined whether dissection of non-aiLNs was required during intentional segmentectomy. Methods This retrospective cohort study included 310 patients who underwent lobectomy and mediastinal LND for non-small cell lung cancer of ≤ 2 cm at the Osaka International Cancer Institute during January 2006 to December 2015. We investigated LN metastasis distribution and evaluated metastases in non-aiLNs distant from the primary lesion. Results Six (1.9%) patients had iLN metastasis. Patients with iLN metastasis did not have primary lesions in the right upper lobe or left upper segment. Of the six patients with iLN metastasis, three had non-aiLN metastasis with a tumor diameter of ≥ 15 mm, with high positron emission tomography standard uptake values (> 3.5). Two patients had multiple LN metastases, and one had solitary LN metastasis. Conclusion Non-aiLN dissection may be unnecessary during segmentectomy of the right upper lobe or left upper segment; however, it should be considered during lower-lobe segmentectomy.