To explore the prognostic value of spread through air spaces and develop a nomogram combined with spread through air spaces in lung squamous cell carcinoma.

Background: Spread through air spaces (STAS), as a new pattern of invasion, was officially proposed by the World Health Organization (WHO) in 2015, and its importance was reiterated in 2021. Since it was proposed, numerous studies have confirmed that STAS is associated with poor prognosis, but there are relatively few studies related to the prognosis of postoperative patients with lung squamous cell carcinoma. By synthesizing different predictive variables, nomogram can obtain the individual digital probability of clinical events succinctly and intuitively, which can meet our needs for personalized medicine. In this study, our goal is to explore the prognostic value of STAS in lung squamous cell carcinoma and establish a prognostic prediction model. Methods: Under six inclusion criteria, 540 postoperative patients were enrolled in the study. STAS was re-evaluated by pathologists at Ningbo Clinicopathological Diagnosis Center. Progression-free survival (PFS) referred to the time from randomization to the first occurrence of disease progression or death of any cause. Recurrences were confirmed by clinical, radiological or pathological assessment. The survival information was collected by telephone and outpatient follow-up. A total of 540 patients were randomly divided into groups in a 6:4 ratio for survival analysis to determine the correlation between STAS and prognosis. Cox regression was used for univariate and multivariate analysis, so as to establish a predictive model. The assessment of the nomogram was carried out by receiver operating characteristic (ROC) curve analysis, calibration curve analysis and decision curve analysis (DCA). Results: The overall 5-year survival rate was 70.35% in STAS-negative patients and 42.35% in STAS-positive patients. In all cohorts, STAS-negative patients had longer 5-year PFS than STAS-positive patients (P<0.001). Multivariate analysis showed that stage [stage II P=0.008, hazard ratio (HR) =1.792; stage III P<0.001, HR =3.148], tumor differentiation (well-differentiation P=0.021, HR =0.436), and STAS (P=0.026, HR =1.470) were independent predictors of PFS. The area under the curve (AUC) of model 5 in discovery cohort is 0.720, while the AUC of model 5 in validation cohort is 0.693. Conclusions: The nomogram combined with STAS can provide a personalized visual survival probability prediction map for postoperative patients with lung squamous cell carcinoma, so as to aid in the pursuit of personalized medicine to a certain extent.