Lobe-specific nodal dissection for clinical stage I-II non-small cell lung cancer: Japanese multi-institutional retrospective study using a propensity score analysis.

Abstract The purpose of this study was to assess the surgical outcomes according to the extent of mediastinal lymph node dissection for NSCLC patients by using a nationwide registry database. From among 11,663 patients in a Japanese lung cancer registry study for 2004, a total of 5,392 patients with c-stage I-II NSCLC that was completely resected by lobectomy and either systematic or lobe-specific nodal dissection (SND or LSD) were enrolled. Patients who received preoperative therapy or who had middle-lobe tumor were excluded. In the LSD group, inferior mediastinal (subcarinal) nodes were not dissected for upper-lobe tumors, and superior mediastinal nodes were not dissected for lower-lobe tumors. To reduce the selection bias, an inverse probability of treatment weighting (IPTW) method using a propensity score was implemented. LSD and SND were performed in 1,268 (23.5%) and 4,124 (76.5%) patients, respectively. The LSD group included more upper-lobe and c-stage I tumors, and less pN2 than the SND group. Extended pN2 outside LSD area was found in 3.2% of the SND group. The 5-year overall survival was 81.5% in the LSD group and 75.9% in the SND group. An IPTW-adjusted Cox model showed that LSD did not have a negative prognostic impact, and instead was associated with favorable survival (hazard ratio=0.68, 95% CI: 0.60-0.77). This retrospective registry study suggested that LSD is an alternative to SND for selected c-stage I-II NSCLC patients. Future prospective studies are warranted whether LSD is applicable and provide clinical benefit for general c-stage I-II NSCLC population.