Retrospective Analysis of Clinical and CT Features to Predict Spread Through Air Space in Stage IA Lung Adenocarcinoma

Referring from Global Cancer Report 2020, lung cancer remains the leading cause of tumor death, with adenocarcinoma as the primary histological subtype. In 2021, the World Health Organization (WHO) proposed a new classification standard for lung cancer, dividing adenocarcinomas into in-situ adenocarcinomas, microinvasive adenocarcinomas, and invasive adenocarcinomas based on their invasive development.

Due to the widespread popularization of early screening for lung cancer, a growing number of IA lung adenocarcinomas cases manifesting as lung nodules have been detected, and surgical resection remains the most critical treatment options for such individuals. With the emergence of relevant research results, sublobectomy has become a preferred method for early stage IA lung adenocarcinoma. However, some individuals with lung adenocarcinoma in stage IA undergoing sublobectomy still have recurrence and metastasis, in which spread through air spaces (STAS) plays vital role.

STAS was formally proposed by WHO in 2015 as a new invasion mode of invasive lung adenocarcinoma. STAS is characterized by pathological micropapillary clusters, solid nests, or isolated cells located beyond the tumor margin, counting one or more, infiltrating the air spaces within the surrounding lung parenchyma and detached from the primary tumor, rather than forming distinct tumor islands. A number of studies have pointed out that STAS is associated with poor prognosis of patients, many researchers continue to favor lobectomy when treating patients with stage IA lung adenocarcinoma exhibiting positive STAS.

Due to the limitations of intraoperative frozen section in predicting STAS, preoperative application of clinical and imaging features in predicting STAS shows great advantages. Former research has suggested that clinical and imaging characteristics can predict occurrence of STAS, despite the difference of results from different studies. Onozato et al. believe that smokers are more likely to develop STAS, which is consistent with the study by Shiono et al. However, Uruga et albelieved that the occurrence of STAS was unrelated to smoking. Warth et al. believed that male lung adenocarcinoma patients were more prone to STAS, while Kadota stated the occurrence of STAS was unrelated to patient gender.

However, the sample size included in these previous studies is small, and the parameters included by various scholars are different, and there is still a lack of large sample studies systematically analyzing clinical and imaging characteristics to predict the spread through air space of stage IA lung adenocarcinoma. Therefore, we plan to carry out this study. Based on a large sample size, the clinical and imaging characteristics of patients with stage IA lung adenocarcinoma were comprehensively analyzed to predict the spread through air space, so as to provide a reference for the selection of surgical methods

Inclusion criteria

Preoperative CT images reported that the maximum diameter of pulmonary nodules was less than 3 cm

All subjects provided CT imaging obtained from Yunnan Cancer Hospital within a 2-week period prior to surgery

Postoperative pathological diagnosis of invasive lung adenocarcinoma

Remote metastasis was excluded by preoperative imaging (CT, PET-CT, ultrasound, etc.)

Age ≥ 18 years

Exclusion criteria

Incomplete collection of medical records, imaging data, or hematology data

Preoperative complications of other malignant tumors

Unclear correspondence between postoperative pathological report and preoperative CT nodule location

Images do not meet analysis conditions due to pulmonary infection or large respiratory motion artifacts

Postoperative pathology revealed two or more nodules classified as infiltrating adenocarcinoma

Prior lung surgery or preoperative neoadjuvant therapy