Lymph node dissection in small peripheral lung cancer: Supplemental analysis of JCOG0802/WJOG4607L

Objective The optimal region of lymph node dissection (LND) during segmentectomy in patients with small peripheral non-small cell lung cancer requires clarification. Through a supplemental analysis of the JCOG0802/WJOG4607L, we investigated the associated factors, distribution, and recurrence pattern of lymph node metastases (LNM) and proposed the optimal LND region. Methods Of the 1106 patients included in the JCOG0802/WJOG4607L, 1056 patients with LNDs were included in this supplemental analysis. We investigated the distribution and recurrence pattern of LNMs along with the radiological findings (with ground glass opacity [GGO], part-solid tumor; without GGO component, pure-solid tumor). Results The radiological findings were the only significant factor for LNMs. Of 533 patients with part-solid tumors, eight (1.5%) had LNMs. Further, only three (0.5%) patients had pN2 disease, and no patients had interlobar LNMs from non-adjacent segments. Of the 523 patients with pure-solid tumors, 55 (10.5%) had LNMs, and 28 (5.4%) had pN2 disease. Five patients had metastases to non-adjacent interlobar lymph nodes (LNs). Two (2.0%) patients with S6 tumors had upper mediastinal LNMs. In addition, the incidence of mediastinal LN recurrence in patients with S6 lung cancer was greater in those who underwent selective LND than those who underwent systematic LND (p = 0.0455). Conclusions Non-adjacent interlobar and mediastinal LND have little impact on pathological nodal staging in patients with part-solid tumors. In contrast, selective LND is recommended at least for patients with pure-solid tumors.