Comparative validation of clinical staging based on solid component versus total tumor size in resected lung adenocarcinoma.

Objectives: To compare clinical staging based on total tumor size with that of solid component size using the same criteria.

Materials And Methods: Patients who underwent curative resection for clinical stage IA1-IB adenocarcinoma between 2011 and 2021 were retrospectively included. Patients were re-staged according to the criteria of the current TNM staging using total tumor size (cStage) and solid component size (cStage). Discrimination and prognostication for overall survival and freedom from recurrence were compared between cStage and cStage. The correlation with pathologic risk factors (high-grade pattern, lymphovascular invasion, and pathologic lymph node metastasis) was assessed.

Results: A total of 4680 patients were included. From cStage to cStage, 32.6% of patients (1525/4680) were downstaged. Overall survival stratification within clinical stage IA-3 for subsolid lesions was enabled only with cStage. Both cStage and cStage demonstrated mortality risk stratification between neighboring stages from IA1 to IB (all p < 0.05); however, discrimination (C-index: 0.732 vs. 0.721) and prognostication (Akaike Information Criterion (AIC): 8609 vs. 8645; R: 0.084 vs. 0.077) were better in cStage. Additionally, cStage showed an improved correlation with pathologic risk factors and pathologic lymph node metastasis (both any pN and pN2). cStage also showed improved discrimination (C-index: 0.731 vs. 0.722) and prognostication (AIC: 12,257 vs. 12,316; R: 0.102 vs. 0.091) than cStage for freedom from recurrence.

Conclusion: Using the same size criteria, clinical staging based on solid component size provides enhanced performance and correlation with pathologic risk factors compared to total tumor size.

Key Points: Question A direct comparative validation of clinical staging based on solid component size versus total tumor size under the same criteria has not been conducted. Findings Correlation with pathologic risk factors and lymph node metastasis, especially pN2, was stronger in clinical staging based on solid component. Clinical relevance It is reasonable for future revisions to be based on the current scheme using solid component size.