Clinical, pathological, and computed tomography morphological features of lung cancer with spread through air spaces

Abstract

Background: Spread through air spaces (STAS) is significantly associated with decreased overall survival (OS) and reduced recurrence-free survival. However, there are no reliable methods to confirm the presence of STAS before surgery. The sensitivity and specificity of the intraoperative frozen section diagnosis of STAS are not satisfactory. This study sought to determine the clinical, pathological, and computed tomography (CT) features of lung cancer with STAS before surgery to guide treatment decisions.

Methods: The data of 121 patients who were positive for STAS and 121 who were negative for STAS as confirmed by surgery and pathology were collected at Jiangsu Cancer Hospital from January 2020 to December 2022. The differences between the two groups in terms of the clinical, pathological, and CT characteristics were compared.

Results: STAS occurred not only in lung adenocarcinoma (LUAD) (106 of 121, 87.6%), but also in other pathological types of lung cancer (15 of 121, 12.4%). STAS was significantly correlated with pathological invasiveness [pathological differentiation, tumor, node, metastasis (TNM) staging, vascular invasion, and pleural invasion; all P<0.05]. STAS was most common in solid tumors (95 of 121, 78.51%). The receiver operating characteristic (ROC) curve showed that the optimal cut-off value for diagnosing STAS based on diameter is 1.55 cm with a sensitivity of 73.3% and a specificity of 47.9%. The percentage of solid components (PSC) is an independent influencing factor of lung cancer with STAS [odds ratio (OR) =111.27; P<0.05] with an optimal cut-off value of 63%, a sensitivity of 92.5%, and a specificity of 72.7%. In the part-solid nodules, the occurrence rate of STAS increased as the PSC increased. STAS was only observed in part-solid nodules with a PSC greater than 25%. Among the CT morphological features, lobulation was an independent influencing factor of lung cancer with STAS (OR =3.513; P<0.05), and persistent indistinct margin ground-glass opacity around the primary lesion of lung cancer (21 of 121, 17.36%) and satellite foci (9 of 121, 7.44%) strongly indicated the existence of STAS.

Conclusions: The clinical, pathological and CT features of STAS may guide clinicians to develop appropriate strategies and improve the survival rate of patients.

Keywords: Lung cancer; computed tomography (CT); ground-glass nodule; influencing factors; spread through air spaces (STAS).

Figure 1

Flowchart showing patient inclusion and exclusion in the study. STAS, spread through air spaces; CT, computed tomography.

Figure 2

Receiver operating characteristic curve for assessing the diagnostic efficiency of the diameter and percentage of solid components. ROC, receiver operating characteristic; AUC, area under the curve; PSC, percentage of solid components.

Figure 3

CT and pathological images of a 68-year-old man with lung cancer. (A-C) CT images showing a nodule in the left upper lung with lobulation and spiculation at the edges. Ground-glass opacity with a blurred border was observed around the nodule (non-distal) (white arrow). (D) Surgical pathology confirmed a poorly differentiated neuroendocrine carcinoma with STAS (black arrow). HE stain, 200×. CT, computed tomography; STAS, spread through air spaces; HE, hematoxylin and eosin.

Figure 4

CT and pathological images of a 39-year-old man with lung cancer. (A-C) CT images showing a mass in the left lower lung. A mixed ground-glass nodule was identified 1.5 cm away from the mass (white arrow). (D) Surgical pathology confirmed that the mass was a peripheral nodular lung adenocarcinoma (papillary type 50%, acinous type 30%, micropapillary type 20%) with STAS (black arrow). HE stain, 200×. CT, computed tomography; STAS, spread through air spaces; HE, hematoxylin and eosin.