A Comparative Analysis of Nodal Spread in Solid-Predominant vs Pure-Solid Stage IA Hypometabolic Lung Adenocarcinoma

This study investigated the oncologic role of the ground-glass opacity (GGO) component in lymph node dissection for clinical (c)-stage IA solid-predominant hypometabolic lung adenocarcinoma with a low maximum standardized uptake value (SUVmax).

The study retrospectively reviewed 192 patients who underwent anatomic lung resection for c-stage IA2 to IA3 solid-predominant lung adenocarcinomas with hypometabolic activity (SUVmax ≤2.7) between 2008 and 2017. Patients were classified as having part-solid (0.5< consolidation-to-tumor ratio < 1.0) or pure-solid (consolidation-to-tumor ratio = 1.0) tumors. The prognostic significance of the GGO was evaluated using Gray's model, with a competing risk of death without recurrence.

The median follow-up duration was 108.3 months. Overall, 134 (70%) and 58 (30%) patients had part-solid and pure-solid tumors, respectively. Of these, 163 (85%) patients received a diagnosis of c-stage IA2 disease, and 156 (81%) underwent lobectomy. Mediastinal lymph node dissection was performed in 144 (75%) patients. Pathologic nodal metastases were observed in 5 cases (8.6%), which were found to be pure-solid tumors. Among the 5 cases, N1 metastasis was detected in 2, and N2 metastasis was detected in 3. The proportion of pathologic nodal metastases (8.6% vs 0%; P < .01) was significantly higher in the pure-solid group than in the part-solid tumor group. None of the patients with part-solid tumors showed postoperative disease progression. The 5-year cumulative incidence of recurrence was higher in the pure-solid group than in the part-solid group (12.1% vs 0%; P < .01).

Lymph node dissection is warranted in c-stage IA2 to IA3 lung adenocarcinoma with a pure-solid appearance, even with hypometabolic activity.