Predictive value of radiological features on spread through air space in stage cIA lung adenocarcinoma

Spread through air space (STAS) is a risk factor for disease recurrence in patients with stage IA lung adenocarcinoma (LUAD) who undergo limited resection. Preoperative prediction of STAS could help intraoperative surgical decision-making in small LUAD patients. The aim of the study was to evaluate the predictive value of radiological features on STAS in stage cIA LUAD.

A case-control study was designed through retrospective analysis of the radiological features of patients who underwent curative surgery for LUAD with a clinical tumor size ≤3 cm. Univariable and multivariable analyses were used to identify the independent risk factors for STAS. The predicted probability of STAS was calculated by a specific formula. Receiver operating characteristic (ROC) curves were used to determine a cut-off value with appropriate specificity while maintaining high sensitivity for STAS positivity.

STAS was frequently observed in acinar predominant (P<0.001), micropapillary predominant (P<0.001) and solid predominant (P<0.001) tumors and was significantly associated with larger pT size (P<0.001), presence of micropapillary component (P<0.001), lymphovascular invasion (LVI) (P<0.001), visceral pleura invasion (VPI) (P<0.001), both N1 and N2 lymph node metastasis (P<0.001) and ALK rearrangement (P<0.001). STAS-positivity was significantly associated with the presence of cavitation (P=0.047), lobulation (P=0.009), air bronchogram (P<0.001), and vascular convergence (P=0.016) and was also associated with greater maximum tumor diameter (P<0.001), maximum solid component diameter (P<0.001), maximum tumor area (P<0.001), consolidation/tumor ratio (CTR) (P<0.001), tumor disappearance ratio (TDR) (P<0.001) and computed tomography (CT) value (P<0.001). Multivariable analysis showed that STAS was associated with air bronchogram (P=0.042), maximum tumor diameter (P=0.015), maximum solid component diameter (P=0.022) and CTR (P<0.001). The ROC curve showed that the area under the curve (AUC) was 0.726 in the model for predicting STAS, with a sensitivity and specificity of 95.2% and 36.8%, respectively.

STAS-positive LUAD was associated with air bronchogram, maximum tumor diameter, maximum solid component diameter and CTR. These radiological features could predict STAS with excellent sensitivity but inferior specificity.