Lymph Node Involvement and Radiological Predictors of Invasiveness in Pure Ground-Glass Adenocarcinomas: the GORDON study

Background: Pure ground-glass opacities (pGGOs) have been recognized as radiologic manifestations of early-stage lung adenocarcinomas, typically characterized by slow progression and a low risk of metastasis. The study aim to evaluate the incidence of lymph node involvement in patients undergoing pGGO resection. Secondary objectives included assessing lymph node recurrence-free interval and correlating pGGO radiological features with final histology. Methods: This multicenter retrospective study (January 2013-June 2024) included patients who underwent pulmonary resection and lymphadenectomy for pGGOs; data were recorded in the GORDON database (Ground-glass Opacities Retrospective Database for Oncological N-status). Histological diagnosis, lymph node involvement and recurrence were analyzed. Qualitative and quantitative radiological features of invasive and non-invasive pGGOs were compared, and ROC analysis identified predictive parameters for invasiveness. Results: Of 400 pGGOs, 346 (86%) were invasive adenocarcinomas, 40 (10%) minimally invasive, and 14 (4%) adenocarcinomas in situ. No lymph node metastases were detected. Five-year nodal recurrence was 0%. Invasive pGGOs showed larger radiological diameter (22 vs. 16 mm, p < 0.001), higher CT attenuation (-336 vs. -562 HU, p < 0.001), higher difference CT values (-493 vs. -313 HU, p < 0.001), and higher relative attenuation (p < 0.001). A combined ROC curve analysis identified a radiological diameter of 18 mm and CT density of -390 HU as predictive cut-offs for invasiveness (AUC 0.874). Conclusions: Adenocarcinomas presenting as pGGOs are low-risk lesions with rare lymph node involvement or recurrence, suggesting that lymphadenectomy may be unnecessary. Preoperative chest CT enables risk stratification of lesion invasiveness, supporting tailored therapeutic approaches.