Spread Through Air Spaces (STAS) in Non−Small Cell Lung Carcinoma

Abstract

Tumor spread through air spaces (STAS) is associated with locoregional recurrence in patients undergoing limited resection (LR) for non−small cell lung carcinoma (NSCLC). We hypothesized that the observation of STAS in both the initial LR specimen and the additional resection specimen from the same patient, processed using different knives, would provide evidence that STAS is an in vivo phenomenon contributing to locoregional recurrence. We retrospectively identified patients with NSCLC (9 adenocarcinoma, 1 squamous cell carcinoma) who underwent LR, had STAS in the LR specimen, and underwent additional resection (lobectomy or LR). The LR and additional resection specimens from each patient were processed at different times using different tissue-processing knives. All specimens were analyzed for STAS. All 10 patients underwent LR with negative margins (R0). All additional resection specimens had STAS: 8 patients had STAS clusters in their completion lobectomy specimens, and 2 had STAS in their additional LR specimens. In 2 patients, STAS was found in the completion lobectomy specimen only after extensive sampling (>10 sections) from the staple line adjacent to the initial LR. The presence of STAS in both the LR and the additional resection specimen processed using different knives supports the concept that STAS is an in vivo phenomenon, rather than an artifact from tissue processing. This observation indicates that occult STAS tumor cells can be present in the lung tissue of the remaining unresected lobe after LR and supports the concept that STAS is a contributing factor for locoregional recurrence following LR.

Impact of preoperative biopsy on tumor spread through air spaces in stage I non-small cell lung cancer: a propensity score-matched study

“…However, some scholars have questioned STAS, arguing that it is only the spread of tumor cell clusters caused by knife cutting during specimen processing, and called it "Spread Through a Knife Surface" [ 12 ]. Recently, more and more studies have shown that STAS is an in vivo phenomenon rather than an artifact caused by specimen handling procedures [ 13 , 23 , 24 ]. However, could this in vivo phenomenon be another manipulation artifacts, caused by preoperative invasive biopsy?…”

“…Among them, STAS is an important risk factor for tumor recurrence after surgery for stage I NSCLC [9][10][11]. However, the existence of STAS has also been questioned by many scholars, who believe that STAS may be an artifact of human manipulation due to spreading caused by knife cuts during specimen processing [12], although some studies have been conducted on the specimen retrieval process and confirmed that STAS is an in vivo phenomenon that exists preoperatively and is not a result of spreading caused by specimen processing [13]. Whether STAS is associated with preoperative invasive manipulation has not been reported.…”

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

“…In addition, in specimens of lung adenocarcinoma with STAS as the main histological pattern, it was observed that the area of floating tumor mass of STAS was not the area while the knife cutting through the main tumor. After Gross et al (34) found STAS in the first surgical resection (R0 resection), several tumor cell clusters could still be found in the air cavity of the normal lung tissue resected in the subsequent second surgery. Metovic et al (35) confirmed through a prospective study that there was no significant difference in the incidence of STAS between fresh tissues and formalin-fixed tissues, and there was no obvious dominant distribution of STAS in the air cavity of the lung parenchyma before and after the knife cut through the tumor.…”

Pretreatment prediction of tumour spread through air spaces in clinical stage I non-small-cell lung cancer

“…The incidence of STAS in stage I NSCLC reported in previous studies ranged from 14.8% to 55.4% [ 4 , 11 ]. As the understanding of STAS has improved, many studies have shown that STAS is an in vivo phenomenon rather than an artefact of specimen handling procedures [ 12 , 13 ]. Therefore, there is a growing interest in the diagnosis of STAS.…”