Optimal Surgical Margin to Avoid Locoregional Recurrence for Non-small Cell Lung Cancer Larger than 2.0 cm: A Retrospective Study

Background. A parenchymal surgical margin of“the clinical tumor size or more” or “2.0 cm or more” has been widely recognized as the optimal margin distance to avoid locoregional recurrence after sublobar resection for non-small cell lung cancer (NSCLC) of 2.0 cm or less. However, the safe margin distance to avoid locoregional recurrence for NSCLC larger than 2.0 cm remains unclear. Patients and Methods. Among 1,338 patients with resected primary lung cancers at two institutions between 2007 and 2016, 85 clinical N0M0 patients with NSCLCs larger than 2.0 cm who underwent sublobar resection were extracted. We classified these 85 NSCLCs as ground glass opacity (GGO)-dominant type or solid-dominant type according to computed tomography (CT) findings. Clinicopathological characteristics and the association between locoregional recurrence and margin distance were evaluated. Results. The median clinical tumor size was 2.5 (2.1-4.9) cm. Based on CT findings, 14 tumors (16%) were considered GGO-dominant type and 71 (84%) were solid-dominant type. No lymph node metastasis, lymphatic permeation or vascular invasion was pathologically confirmed in GGO-dominant type. All GGO-dominant tumors were resected with a margin distance the size of the solid part on CT or more, resulting in no local recurrence, whereas, solid-dominant tumors recurred locally even if they were resected with a margin distance of “the clinical tumor size or more”. Conclusions. The optimal surgical margin for NSCLC larger than 2.0 cm was “the size of the solid part on CT or more” for GGO-dominant type, but undefinable for solid-dominant type.