Toward improving prognosis prediction in patients undergoing small lung adenocarcinoma resection: Radiological and pathological assessment of diversity and intratumor heterogeneity

Abstract

ObjectivesPrediction of prognosis based on the ground-glass opacity (GGO) ratio for small (≤2 cm) lung adenocarcinomas is not completely accurate. The aim of this study was to clarify the diversity of small adenocarcinomas and to identify ways to more accurately predict prognosis. Materials and methodsWe retrospectively reviewed 62 patients (64 lesions) that underwent lobectomy for small (≤2 cm) lung adenocarcinoma. Proportions of histological components were measured and the presence of tumor spread through air spaces (STAS) was assessed. The correlations between GGO and histological components were examined. Furthermore, histological components of pure GGO lesions were analyzed using CT values. The intratumor heterogeneity of programmed death ligand 1 (PD-L1) expression was analyzed in 40 lesions. Furthermore, the relationship between CT/histological findings and prognoses was analyzed. ResultsIn 13 pure GGO lesions, 7 (53.8%) lesions contained invasive components such as papillary, acinar, solid, and colloid. Tumor spread through air spaces (STAS) was also found in pure GGO lesions. Pure GGO lesions containing invasive components (p = 0.002) and STAS-positive lesions (p = 0.011) demonstrated strongly higher CT value. Differences in expression of PD-L1 among histological subtypes were observed in four of six (66.7%) PD-L1 positive lesions. Patients with papillary component, positivity for STAS, or CT value ≥ -140.6 Hounsfield units (HU) had significant poorer prognoses than patients without those in disease-free survival analyses (p = 0.007, p = 0.048, p = 0.012). Patients with the CT value < -383.4 HU and GGO ≥ 50% did not have recurrence. ConclusionsInvasive component and STAS can be present even in small GGO lesions, and patients with papillary components or STAS showed significantly poorer prognoses. STAS-positive lesions were strongly associated with a high CT value, and combined use of GGO ratio and CT value may be able to predict recurrences of lung cancer more accurately.