Prognostic Impact of Inadequate Lymph Node Evaluation in Early-Stage Lung Adenocarcinoma with Micropapillary or Solid Components.

The presence of micropapillary (MP) or solid (S) components is associated with a high risk of metastasis and recurrence. The aim of this study was to evaluate the impact of inadequate lymph node dissection on the prognosis of patients with ≤3 cm pN0M0 non-mucinous invasive adenocarcinoma with MP/S components. A total of 724 patients from two hospitals were retrospectively included. The Commission on Cancer (COC) Operative Standard 5.8 specifies sampling of three or more mediastinal plus one or more hilar lymph node stations. Patients were grouped according to examined lymph node (ELN) count (<16 vs. ≥16) and COC criteria (COC- vs COC+). Follow-up was performed to assess overall survival (OS) and recurrence-free survival (RFS). Statistical analysis included Kaplan-Meier curve (with log-rank test), propensity score matching, restricted cubic spline regression, and Cox proportional hazards models. After 1:1 propensity score matching, 96 and 235 matched pairs were generated in the ELN and COC groups, respectively, with balanced baseline characteristics. Kaplan-Meier analysis showed no significant differences in OS or RFS between the ELN <16 and ≥16 groups or between the COC- and COC+ groups (all p>0.05), with comparable probability of recurrence (16.6% vs 15.3%, 18.8% vs 15.0%, p>0.05). Restricted cubic spline analysis indicated a nonlinear association between ELN and OS, with an inflection point at approximately seven, but subgroup Cox regression indicated that ELN had no independent prognostic significance. For ≤3 cm pN0M0 non-mucinous invasive adenocarcinoma with MP/S components, inadequate lymph node dissection may not worsen clinical outcomes. This retrospective finding warrants prospective validation.