Retrospective study of radiologic phenotype and size dependence of adverse histologic features and recurrence in resected LUAD

The eighth edition TNM classification measures part-solid lung adenocarcinoma (LUAD) by the solid component alone. A retrospective study at Seoul National University Bundang Hospital (Seongnam, South Korea) examined whether CT-measured size carries the same pathologica and prognostic meaning in part-solid and solid LUAD. The study enrolled 3857 consecutive patients with resected non-mucinous LUAD (2011-2022), using phenoptype and size from preoperative CT reports. Tumors were part-solid in 2100 and solid in 1757 patients. In part-solid tumors, high-grade (HG) patterns, micropapillary component, and spread through air spaces (STAS) rose most steeply at 1.25-1.36 cm of total size (0.85-0.93 cm of solid component); in solid tumors, HG patterns and STAS were already frequent at the smalles measured sizes. Lymphovascular, pleural, and nodal involvement became prevalent at larger sizes in both phenotypes. Among 3580 patients analyzed for recurrence (467 recurrences; median follow-up 56.6 months) solid tumors had higher cumulative incidence of recurrence (CIR) than part-solid tumors within each matched solid-component stratum. In part-solid tumors, 5-year CIR was 1.4% when HG morphology was the most advanced feature, 11.0% with local invasion, and 50.0% with nodal involvement. The authors conclude that measuring the solid component narrows but does not close the difference in pathologic risk between part-solid and solid LUAD of the same size.