Significance of histologic subtype size as a prognostic indicator in stage IA lung adenocarcinoma

BACKGROUND: Predicting prognosis is complex due to a unique characteristic in stage IA lung adenocarcinoma. The feature indicated heterogeneous histologic subtype and ground glass opacity (GGO). Many studies demonstrated different prognoses according to histologic subtype or non-GGO lesion. This study aimed to evaluate the clinical outcomes following each histologic subtype size in stage IA lung adenocarcinoma and identify the prognostic impact of each histologic subtype size. METHODS: The medical records of 550 patients with pathological stage IA lung adenocarcinoma were reviewed. Histologic subtype size was estimated by multiplying the tumor’s maximum diameter by the proportion of each histologic subtype. Univariate and multivariate analyses were conducted to identify the prognostic role of each histologic subtype size in stage IA lung adenocarcinoma. RESULTS: The median age and tumor size were 63 [25–82] years and 1.8 [0.3–3] cm, respectively. Acinar (42.0%) and lepidic (44.4%) were the most common among the predominant subtype. Each subtype size was estimated and re-categorized following the current staging system. The disease-free interval (DFI) was significantly different following each histologic subtype size. Multivariate analysis for DFI revealed more acinar, micropapillary, and solid subtypes and fewer lepidic subtypes with worse prognoses. CONCLUSIONS: The prognosis for DFI is determined through a complex process by various variables in stage IA lung adenocarcinoma. Each subtype size has a more prognostic impact than the predominant subtype.