Comprehensive analysis for clarifying transcriptomics landscapes of spread through air spaces in lung adenocarcinoma

Histology of Bronchiolar Tumor Spread Through Air Spaces

The clinical significance of lung tumor spread through air spaces (STAS) has been extensively studied, and is recognized as a unique pattern of invasion. Previous studies of STAS have focused primarily on STAS in alveolar spaces, whereas STAS in the bronchiolar spaces (bronchiolar STAS) has been described in only a few case reports only. Here, we examined 306 cases of primary lung adenocarcinoma and found that bronchiolar STAS was present in 18%. Bronchiolar STAS was associated with an inferior prognosis, more advanced stage, and higher histologic grade. No significant difference in clinicopathological factors or prognosis was observed between cases with bronchiolar STAS and those with alveolar STAS alone. Notably, bronchiolar STAS often occurred simultaneously with alveolar STAS and endobronchial spread of adenocarcinoma, particularly when bronchiolar STAS was present outside the main tumor. We also identified cases where bronchiolar STAS and endobronchial spread of adenocarcinoma occurred simultaneously in the same bronchi or bronchioles located outside the main tumor, as well as cases with bronchiolar STAS adjacent to intrapulmonary metastatic nodules. Our results highlight the significant role of bronchiolar STAS in the aerogenous spread of adenocarcinoma cells. Bronchiolar STAS can be regarded as a histologic variant of alveolar STAS. This study also supports the idea that STAS is not a tissue processing artifact, but a true biological process with clinical implications, offering histologic evidence of aerogenous spread in lung adenocarcinoma.

The significance of spread through air spaces in the prognostic assessment model of stage I lung adenocarcinoma and the exploration of its invasion mechanism

PURPOSE

Spread through air spaces (STAS) is a crucial invasive mode of lung cancer and has been shown to be associated with early recurrence and metastasis. We aimed to develop a prognostic risk assessment model for stage I lung adenocarcinoma based on STAS and other pathological features and to explore the potential relationship between CXCL-8, Smad2, Snail, and STAS.

METHODS

312 patients who underwent surgery at Harbin Medical University Cancer Hospital with pathologically diagnosed stage I lung adenocarcinoma were reviewed in the study. STAS and other pathological features were identified by H&E staining, and a prognostic risk assessment model was established. The expression levels of CXCL8, Smad2, and Snail were determined by immunohistochemistry.

RESULTS

The nomogram was established based on age, smoking history, STAS, tumor lymphocyte infiltration, tissue subtype, nuclear grade, and tumor size. The C-index for DFS was (training set 0.84 vs validation set 0.77) and for OS was (training set 0.83 vs validation set 0.78). Decision curve analysis showed that the model constructed has a better net benefit than traditional reporting. The prognostic risk score validated the risk stratification value for stage I lung adenocarcinoma. STAS was an important prognostic factor associated with stronger invasiveness and higher expression of CXCL8, Smad2, and Snail. CXCL8 was associated with poorer DFS and OS.

CONCLUSIONS

We developed and validated a survival risk assessment model and the prognostic risk score formula for stage I lung adenocarcinoma. Additionally, we found that CXCL8 could be used as a potential biomarker for STAS and poor prognosis, and its mechanism may be related to EMT.