Frequent aerogenous spread with decreased E-cadherin expression of ROS1- rearranged lung cancer predicts poor disease-free survival

Prognosis of spread through air spaces in invasive mucinous lung adenocarcinoma after curative surgery

INTRODUCTION

The purpose of this study is to investigate the prognostic impact of spread through air spaces (STAS) in invasive mucinous adenocarcinoma (IMA).

MATERIALS AND METHODS

From 2015 to 2019, patients who underwent complete resection of IMA were extracted from the prospective database. Multivariable Cox-regression analysis and inverse probability of treatment weight (IPTW) - adjusted log-rank test for 5-year recurrence-free survival (RFS) were performed.

RESULTS

STAS was observed in 39.1% (53 out of 133). The STAS (+) group shows larger tumor size (2.9 ± 2.4 cm vs 3.8 ± 2.4 cm, p = 0.031) and higher incidence of lympho-vascular invasion (6 [7.5%] vs 18 [34.0%], p < 00.001) compared to the STAS (-) group. The 5-year RFS was 66.1% in the STAS (+) group and 91.8% in the STAS (-) group (p < 00.001), and the incidence of locoregional recurrence was significantly higher in the STAS (+) group than the STAS (-) group (1 [1.2%] vs 12 [22.6%], p < 00.001). Multivariable analysis revealed that STAS was associated with poor prognosis for all-recurrence (hazard ratio 2.81, 95% confidence interval 1.01-7.81, p = 0.048). After IPTW adjustment, 5-year RFS was 66.3% in the STAS (+) group and 92.9% in the STAS (-) group (p = 0.007), and risk for locoregional recurrence was greater in the STAS (+) group than the STAS (-) group (1.1 [0.9%] vs 20.8 [16.6%], p < 00.001).

CONCLUSIONS

STAS showed negative prognostic impact on all-recurrence, especially due to locoregional recurrence, after curative resection of IMA.

The effect of spread through air spaces on postoperative recurrence-free survival in patients with multiple primary lung cancers

PURPOSE

The purpose of the study was to investigate the effect of spread through air spaces (STAS) on the postoperative prognosis of patients with multiple primary lung cancers staged from IA to IB based on tumor size.

METHODS

Clinicopathological and follow-up data of 122 patients with multiple primary lung cancers diagnosed at stages IA-IB and surgically treated at the Department of Thoracic Surgery, Shenzhen people's Hospital from January 2019 to December 2021 were retrospectively analyzed. The study involved 42 males and 80 females. STAS status was used to divide them into two groups (87 cases in STAS (-) and 35 cases in STAS (+)). A logistic regression analysis, univariate and multivariate Cox regression analysis, and Kaplan-Meier curves (K-M) were used to determine how STAS affected recurrence-free survival (RFS) in patients.

RESULTS

STAS (+) had a significantly higher recurrence rate than STAS (-). STAS was predicted by smoking history (P = 0.044), main tumor diameter (P = 0.02), and solid nodules on chest CT (P = 0.02). STAS incidence was not significantly different between lobectomy and sublobar resection groups (P = 0.17). Solid nodules on CT, tumor diameter, vascular invasion, pleural invasion, and STAS were significant predictors of recurrence in the univariate Cox regression analysis. Tumor diameter, pleural invasion and STAS were significant prognostic factors for recurrence in the multivariate Cox regression analysis. Furthermore, STAS (+) group was at greater risk of recurrence than STAS (-) group (34% vs. 0%, P < 0.05)。.

CONCLUSION

Stage IA-IB multiple primary lung cancer patients with STAS (+) had a higher recurrence rate and a shorter overall survival rate.

Overexpression of VEGFA mediated by HIF-1 is associated with higher rate of spread through air spaces in resected lung adenocarcinomas

BACKGROUND

Spread through air spaces (STAS), a newly identified pattern of invasion in lung adenocarcinomas (LACs), is an unfavorable prognostic factor for patients with LAC, but the molecular characteristics and mechanisms underlying STAS have not been adequately explored.

METHODS

In total, 650 pathologically confirmed invasive LAC patients who underwent curative resection between December 2019 and April 2020 were reviewed. Disease-free survival (DFS) and overall survival (OS) were analyzed using the log-rank test and the Cox proportional hazards model. A comparative deep sequencing analysis was conducted to explore the molecular characteristics underlying STAS. Vascular endothelial growth factor A (VEGFA) expression was evaluated by immunoblotting and immunohistochemical analysis using fresh tumor tissue and tissue microarray.

RESULTS

STAS was more prevalent in patients with a smoking history (p < 0.001), high pathological TNM stage (p < 0.001), lymphovascular invasion (p < 0.001), visceral pleural invasion (p < 0.001) and micropapillary/solid histological subtypes (p < 0.001). STAS-negative patients had better DFS (p < 0.001) and OS (p = 0.003) compared to STAS-positive patients with invasive LACs, especially in the lymph node-negative population (p < 0.001). After RNA-sequencing analysis, hypoxia-inducible factor-1 (HIF-1) signaling was enriched and appeared to be strongly correlated with STAS, and more STAS-positive individuals were detected in the higher VEGFA-expressing group (p = 0.042).

CONCLUSIONS

We demonstrated that STAS was an independent prognostic marker of poor clinical outcome, especially in lymph node-negative patients, and that higher VEGFA expression mediated by HIF-1 signaling was associated with an increased STAS rate.

EGFR co-mutation is associated with the risk of recurrence in invasive lung adenocarcinoma with the micropapillary component

BACKGROUND

Invasive lung adenocarcinoma (LUAD) patients with the micropapillary (MPP) component tend to have extremely poor prognosis. To optimize clinical outcomes, a better understanding of specific concurrent gene alterations and their impact on the prognosis of patients with the MPP component is necessary.

METHOD

A total of 621 Chinese patients with surgically resected invasive LUAD who underwent genetic testing for lung cancer were enrolled in this retrospective study. The genomic profiling of major lung cancer-related genes based on next-generation sequencing (NGS) was carried out on formalin-fixed paraffin-embedded tumor samples.

RESULT

Among 621 patients with invasive LUAD, 154 (24.8%, 154/621) had the MPP component. We found that PIK3CA (4.5% vs 1.3%), KRAS (9.1% vs 4.7%), and ROS1 (2.6% vs 0.4%) were more frequent in patients with the MPP component than those without the MPP component (P < 0.05). The co-mutation occurred in 66 patients (10.6%, 66/621), of which 19 patients with the MPP component. Most of them were EGFR co-mutations (89.5%, 17/19), including EGFR and PIK3CA, EGFR and ERBB2, and other types. Patients with the MPP component who harbored EGFR co-mutations showed significantly worse recurrence-free survival (RFS) than single EGFR mutation (median RFS 20.1 vs 30.5 months; hazard ratio [HR]: 8.008; 95% confidence interval [CI]: 1.322-48.508).

CONCLUSIONS

Patients with the MPP component harbored the co-mutation of driver genes had a higher risk of recurrence after surgery, especially in patients with EGFR co-mutation. EGFR co-mutation was a significant prognostic factor for RFS in patients with the MPP component.

[Consensus on Postoperative Recurrence Prediction of Non-small Cell Lung Cancer Based on Molecular Markers]

Significant progress has been made in lung cancer screening, surgery, chemoradiation, targeted therapy, and immunotherapy recently. Surgical resection is the most important treatment for localized non-small cell lung cancer (NSCLC) so far, but there are still many patients who develop local recurrence or distant metastases within 5 years of surgery. Currently, the risk factors of recurrence in patients with NSCLC are mainly based on clinical and pathological features, which hardly identify patients at high risk of recurrence accurately. With the development of new detection technologies, a number of molecular markers that may have a predictive risk of recurrence in NSCLC have been discovered over the years. In order to summarize the molecular markers related to postoperative recurrence in NSCLC patients, we have formulated a consensus on the prediction of postoperative recurrence of NSCLC based on molecular markers. This consensus mainly focuses on the early stage NSCLC patients, discusses and summarizes the risk factors of disease recurrence from the molecular level. It is hoped that more and more valuable information can be provided for the management of patients, so as to provide more guidance for the perioperative management of the patients with early stage NSCLC in the future.
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Prognostic Value of Selected Histologic Features for Lung Squamous Cell Carcinoma

The recent histologic subtyping of lung adenocarcinoma has demonstrated the prognostic values of histologic patterns in this malignancy. However, the histological features of lung squamous cell carcinoma (SCC) are much less established. This short review discusses several promising histological prognostic markers for SCC, including tumor budding, tumor cell nesting, and the spreading of tumors through air spaces. Wherever appropriate, the biological significance of these morphological features was also discussed. The investigators consider that histological prognostic markers are highly valuable in understanding the cancer biology of SCC, and in guiding clinical treatment. However, larger clinical cohorts are needed to better establish the prognostic values of the aforementioned histological markers. The application of modern technologies, including machine-learning, would make the histological analysis accurate and reproducible.

An individual nomogram can reliably predict tumor spread through air spaces in non-small-cell lung cancer

Background

Tumor spread through air spaces (STAS) has been shown to adversely affect the prognosis of lung cancer. The correlation between clinicopathological and genetic features and STAS remains unclear.

Method

We retrospectively reviewed 3075 NSCLC patients between2017-2019. We evaluated the relationship between STAS and patients’ clinicopathological and molecular features. The chi-square test was performed to compare categorical variables. Univariate analysis and multivariate logistic regression analysis were performed to investigate the association of clinical factors with STAS. A nomogram was formulated to predict the presence of STAS.

Results

STAS was identified in 617 of 3075 patients (20.07%). STAS was significantly related to sex (p < 0.001), smoking (p < 0.001), CEA (p < 0.001), differentiation (p < 0.001), histopathological type (p < 0.001), lymphatic vessel invasion (p < 0.001), pleural invasion (p < 0.001), T stage (p < 0.001), N stage (p < 0.001), M stage (p < 0.001), and TNM stage (p < 0.001). STAS was frequently found in tumors with wild-type EGFR (p < 0.001), KRAS mutations (p < 0.001), ALK rearrangements (p < 0.001) or ROS1 rearrangements (p < 0.001). For programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1), STAS was associated with PD-L1 expression level in tumor cells (p < 0.001) or stromal cells (p < 0.001), while PD-1 only in stromal cells (p < 0.001). Multivariable analyses demonstrated significant correlations between STAS and CEA level (p < 0.001), pathological grade (p < 0.001), lymphatic vessel invasion (p < 0.001), pleural invasion (p = 0.001), and TNM stage (p = 0.002). A nomogram was formulated based on the results of the multivariable analysis.

Conclusions

Tumor STAS was associated with several invasive clinicopathological features. A nomogram was established to predict the presence of STAS in patients with NSCLC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02002-1.

Histologic and Molecular Characterization of Non-Small Cell Lung Carcinoma With Discordant ROS1 Immunohistochemistry and Fluorescence In Situ Hybridization

INTRODUCTION

ROS1 immunohistochemical (IHC) positivity requires follow-up with confirmatory testing such as fluorescence in situ hybridization (FISH). Identifying predictive characteristics of false positive ROS1 IHC cases could aid in optimizing testing algorithms, decrease testing costs and preserve tissue.

MATERIALS AND METHODS

Retrospective results were retrieved for 2054 patients with non-small cell lung carcinoma submitted to our laboratory for molecular testing. Reflex ROS1 FISH was done on all ROS1 immunoreactive cases using ROS1 D4D6 antibody. Staining intensity and histo-score was recorded for all ROS1 immunoreactive cases. Results of any additional molecular testing (KRAS, BRAF, EGFR, ALK FISH, RET FISH, MET FISH) were also tabulated.

RESULTS

ROS1 immunoreactivity was seen in 305/2054 (14.8%) cases. Immunoreactivity was weak in majority of the cases with only 4.6% cases having an histo-score >100 and 5.9% of cases had moderate staining intensity. FISH was negative in 99% (302/305) cases with any degree of IHC expression (discordant cases) while 3 cases were positive by FISH. Diffuse strong IHC staining in greater than 90% of the tumor was noted in 6 cases, 3 (0.98%) of which were confirmed to have ROS1 rearrangement by FISH. The discordant cases had significantly higher rates of EGFR mutations (P<0.0005) in comparison to ROS1 IHC negative cases, were seen more often in adenocarcinoma and adenosquamous cell carcinoma (P<0.0005) with lepidic and acinar patterns, and more likely to occur in primary lung carcinomas (P<0.0005).

CONCLUSIONS

False positive ROS1 immunoreactivity was very frequent, occurred more commonly in primary NSCLC cases with acinar and/or lepidic histologies and was more likely in EGFR mutated cases. Using higher positivity thresholds for ROS1 IHC and incorporating the histologic and molecular correlates into algorithmic strategies could result in increased specificity and clinical utility of ROS1 IHC assay.

Tumor-associated macrophage infiltration is associated with a higher rate of tumor spread through air spaces in resected lung adenocarcinomas

OBJECTIVE

Lung cancer can spread in numerous ways, one of which has been suggested to be spread through air spaces (STAS). The tumor immune microenvironment appears to play a significant role in this spread. Particularly, tumor-associated macrophages (TAMs) can create a favorable microenvironment for tumor progression. In this study, we analyzed data from 709 patients with stage 0-IIIA lung adenocarcinoma, resected between 1999 and 2016, and investigated whether immune cell infiltration was associated with the occurrence of STAS and clinical outcome of the disease.

MATERIALS AND METHODS

Tissue microarrays were constructed, and immunohistochemical analysis was performed for CD3, CD4, CD8, CD45RO, CD25, CD20, and CD68. The three tumor areas with the highest density of immune cells were photographed, and the immune cells were quantified. Associations between variables were analyzed using chi-square tests and Mann-Whitney U tests. Recurrence-free probability and overall survival were analyzed using log-rank tests and Cox proportional hazards models.

RESULTS

After analyzing the associations between STAS and each type of immune cell infiltration, high density of CD68 + TAMs was identified as an independent predictor of a high STAS rate (p =  0.014) and was found to be associated with a high risk of recurrence, using univariate analysis (p =  0.008). After adjusting for CD68+ TAMs, pathological stage, and lymphovascular invasion, STAS remained significantly associated with a high risk of recurrence (HR = 3.50, p < 0.001).

CONCLUSION

We demonstrated that a high density of CD68 + TAMs is an independent predictor of an increased STAS rate. Additionally, STAS is correlated with aggressive tumor behavior characteristics.

Current status and perspectives of spread through air spaces in lung cancer

According to the World Health Organization classification of 2015, spread through air spaces (STAS) is a newly recognized pattern of invasion in lung adenocarcinoma. Many researchers have reported that STAS is recognized in all histological subtypes, and there is a strong association between STAS and prognosis in lung cancer. However, there are several technical issues associated with STAS, such as distinction between the actual in vivo phenomenon and an artifact, difficulty in assessing STAS in frozen specimens, and establishing the relationship between morphological and molecular properties of STAS. This review focuses on the current state of knowledge and the outlook of the STAS phenomenon from the perspective of surgeons, pathologists, and radiologists.

The epithelial-mesenchymal transition phenotype is associated with the frequency of tumor spread through air spaces (STAS) and a High risk of recurrence after resection of lung carcinoma

OBJECTIVES

The prognostic value of spread through air spaces (STAS) in lung carcinoma has been validated in independent cohorts. Epithelial-mesenchymal transition (EMT) is a biological process that promotes the migration and invasiveness of tumor cells. To investigate the role of the EMT phenotype in the occurrence of STAS, we analyzed patients with therapy-naive lung adenocarcinoma and squamous cell carcinoma undergoing lobectomy (n = 635).

MATERIALS AND METHODS

STAS was defined by the presence of tumor cells within air spaces in the lung parenchyma beyond the edge of the main tumor. The expression of E-cadherin, vimentin, and ®-catenin was evaluated by immunohistochemistry using tissue microarray. Tumors were classified into three EMT phenotypes (epithelial, intermediate, and mesenchymal). Recurrence-free probability and overall survival were analyzed using the log-rank test and the Cox proportional hazards model.

RESULTS

STAS was less frequently observed in tumors with epithelial phenotype than in those with non-epithelial phenotype (p = 0.034), and more frequent in patients with nuclear β-catenin-positive tumors (p < 0.001). The EMT phenotype was an independent prognostic factor of recurrence (mesenchymal vs. epithelial: hazard ratio [HR] = 2.27, p = 0.014; mesenchymal vs. intermediate: HR = 2.13, p = 0.019).

CONCLUSION

We have demonstrated that in patients with resected lung carcinoma, STAS was less frequent in tumors with an epithelial phenotype than in those with non-epithelial phenotype, and that the nuclear translocation of β-catenin was associated with a higher rate of STAS. The mesenchymal state was an independent predictor of high risk of recurrence in patients with STAS.

The differential prognostic impact of spread through air spaces in early-stage lung adenocarcinoma after lobectomy according to the pT descriptor

OBJECTIVES

We evaluated the differential prognostic impact of spread through air spaces (STAS) in early-stage lung adenocarcinoma after lobectomy according to the pT descriptor.

METHODS

The study population included 506 patients who underwent lobectomy with mediastinal lymph node dissection for pT1b, pT1c, and pT2a adenocarcinoma between 2011 and 2016. We divided the study population into 2 groups according to STAS status, ie, STAS (+) versus STAS (-), and stratified them according to the pT descriptor. A Cox proportional hazard model and inverse probability of treatment weight-adjusted Kaplan-Meier curves were used to evaluate the prognostic impact of STAS on recurrence-free survival (RFS) and its independency in each stratum.

RESULTS

Multivariable Cox proportional hazard regression analysis demonstrated that in pT1b and pT1c strata, STAS (+) patients had a 7.02-fold and 2.89-fold greater risk of recurrence than STAS (-) patients, respectively. However, in the pT2a stratum, STAS did not affect RFS. And the RFS of the STAS (+) pT1b/c strata was similar to that of the pT2a stratum. In the pT1b/c strata, inverse probability of treatment weighting-adjusted Kaplan-Meier curves also showed that RFS was significantly worse when STAS was present. Furthermore, the risks for locoregional and distant recurrence were both greater when STAS was present.

CONCLUSIONS

The presence of STAS increased the risk of recurrence independently from other poor prognostic factors in patients with pT1b/cN0M0 adenocarcinoma who underwent lobectomy, but not in pT2a patients. The presence of STAS in pT1b/cN0M0 adenocarcinoma was associated with a similar risk of recurrence to that of pT2aN0M0 adenocarcinoma.

Novel imprint cytological classification is correlated with tumor spread through air spaces in lung adenocarcinoma

OBJECTIVES

Spread through air spaces (STAS) is a risk factor for local recurrence after sublobar resection in lung cancer patients. We recently proposed the novel Nakayama-Higashiyama imprint cytological classification (N-H classification) based on small-sized lung adenocarcinoma surgical specimens, which correlated with histological patterns and nodal involvement. This study aimed to evaluate the correlation between STAS and the N-H classification and to validate the N-H classification as an intraoperative predictor of the presence of STAS.

MATERIALS AND METHODS

We retrospectively analyzed 164 intraoperative imprint cytologies and their paired histologic specimens from patients undergoing surgical resection for lung adenocarcinoma in our institute in 2017-2019. Using the NH classification, imprint cytological findings were classified into 5 groups (Groups I to V) based on cell cluster shape, cell and nucleus size, and the existence of necrosis. We examined the characteristics of imprint cytology and STAS in the resected tissues and analyzed the relationship between them.

RESULTS

Tumor STAS was observed in 29 (17.7 %) cases. The presence of STAS was significantly associated with the NH classification (P < 0.0001). STAS was present in 6 of 57 cases (10.5 %) in NH classification Group II, 11 of 42 cases (26.2 %) in Group III, and 12 of 28 cases (42.9 %) in Group IV/V; STAS was not observed in any case in Group I. Logistic regression analysis revealed that tumors with a ground glass opacity rate of <50 % on computed tomography (P = 0.00867) and Groups III-V of the NH classification (P = 0.00201) were significant independent predictors for STAS.

CONCLUSION

Intraoperative imprint cytology with the N-H classification for lung adenocarcinoma is well correlated with the STAS status of the tumor and might have applications as an intraoperative predictive marker of STAS. This classification may be useful for intraoperative detection of STAS and in the decision-making process for the surgical procedure.

Comprehensive analysis of spread through air spaces in lung adenocarcinoma and squamous cell carcinoma using the 8th edition AJCC/UICC staging system

BACKGROUND

This study aimed to comprehensively investigate the effect of spread through air spaces (STAS) on clinicopathologic features, molecular characteristics, immunohistochemical expression, and prognosis in lung adenocarcinomas (ADC) and squamous cell carcinomas (SQCC) based on the 8th edition AJCC/UICC staging system.

METHODS

In total, 303 ADC and 121 SQCC cases were assessed retrospectively. Immunohistochemical staining was performed for E-cadherin, vimentin, Ki67, survivin, Bcl-2, and Bim. Correlations between STAS and other parameters were analyzed statistically.

RESULTS

STAS was observed in 183 (60.4%) ADC and 39 (32.2%) SQCC cases. In ADC, the presence of STAS was associated with wild-type EGFR, ALK and ROS1 rearrangements, low E-cadherin expression, and high vimentin and Ki67 expression. In SQCC, STAS was associated with low E-cadherin expression and high vimentin and survivin expression. Based on univariate analysis, STAS was associated with significantly shorter disease-free survival (DFS) and overall survival (OS) in ADC. In SQCC, STAS tended to be associated with shorter OS. By multivariate analysis, STAS was an independent poor prognostic factor in ADC for DFS but not OS. Stratified analysis showed that STAS was correlated with shorter DFS for stage I, II, IA, IB, and IIA ADC based on univariate analysis and was an independent risk factor for DFS in stage I ADC cases based on multivariate analysis.

CONCLUSIONS

Our findings revealed that STAS is an independent negative prognostic factor for stage I ADC using the new 8th edition AJCC/UICC staging system. Stage I patients with STAS should be followed up more closely and might need different treatment strategies.

A comprehensive study on the oncogenic mutation and molecular pathology in Chinese lung adenocarcinoma patients

BACKGROUND

Several genetic driver alterations have been identified in micropapillary lung adenocarcinoma (MPA). However, the frequency of co-alteration of ROS1, EGFR, and EML4-ALK is yet unclear. Herein, we investigated the relationship between clinicopathologic characteristics and well-identified driver mutations of MPA compared with non-micropapillary lung adenocarcinoma (LA).

METHODS

Formalin-fixed paraffin-embedded (FFPE) sections derived from lung adenocarcinoma patients who never received adjuvant chemotherapy or radiation therapy prior to surgical resection were collected from October 2016 to June 2019. EGFR mutations, ROS1 rearrangements, and EML4-ALK fusion were identified in a set of 131 MPA and LA cases by using the amplification refractory mutation system (ARMS). The response rate and duration of response were assessed using Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1).

RESULTS

EGFR mutations had occurred in 42 (76.4%) MPA patients and 42 (55.3%) LA patients. Interestingly, ROS1 rearrangements were highly enriched only in the MPA cases (6/55, 10.9%) but rarely in the LA cases (1/76, 1.3%). Furthermore, 7.3% (4/55) MPA samples had double gene mutations, while only 1.3% (1/76) LA cases had double gene alterations. Of 5 patients with harboring two driver oncogene mutations, four patients (80%) obtained partial response, and one patient (20%) suffered recurrence.

CONCLUSIONS

A higher prevalence of ROS1 rearrangement or combined mutations of ROS1, EGFR, and EML4-ALK may play a critical role in the tumorigenesis of MPA. These findings provide a novel therapeutic strategy for patients with malignant MPA through combining TKIs than one TKI.

Significance of tumor spread through air spaces (STAS) in lung cancer from the pathologist perspective

Airspace invasion in lung cancer has been known over the last 30 years, but it was only recently that WHO 2015 formally recognized it as a mechanism of invasion with the terminology of tumor spread through air spaces (STAS). Multiple studies have shown the association of STAS with lower survival and suggest that STAS is an independent prognostic factor across lung adenocarcinoma of all stages and in other histologic subtypes of lung cancer as well. Consequently, STAS is designated as an exclusion criterion of adenocarcinoma in situ and minimally invasive adenocarcinoma; thus, the presence of STAS impacts the diagnosis and staging of lung adenocarcinoma. Further, wedge resection and segmentectomy have been increasingly applied for small node negative tumors and the presence of STAS in those specimens may indicate the requirement of completion lobectomy. Given these significant clinical implications, we, pathologists, need to recognize and appropriately report STAS (possibly including at the time of intraoperative consultation). However, emerging data suggests that more work should be done to improve consensus and identification of STAS, including at frozen section. In this review, the evolution of our understanding of airspace invasion over the past decade, the clinical significance of STAS, and controversies and practical issues associated with the diagnosis of STAS are discussed.

The role of spread through air spaces (STAS) in lung adenocarcinoma prognosis and therapeutic decision making

Spread through air spaces (STAS) was included as a novel pattern of invasion in lung adenocarcinoma by the World Health Organization in 2015. Since then, multiple studies have investigated the association of STAS with clinicopathological and molecular features and its implication in the prognosis of early stage lung cancer patients undergoing different surgery types. The aim of this comprehensive review is to present current data on the role of STAS and its perspective in lung adenocarcinoma management.

Spread Through Air Spaces (STAS) in Lung Cancer: A Multiple-Perspective and Update Review

BACKGROUND

Spread through air spaces (STAS) is a spreading phenomenon of lung cancers, which is defined as tumor cells within air spaces in the lung parenchyma beyond the edge of the main tumor. To date, several articles have reviewed the studies concerning the significance of STAS; however, most articles focused on the prognosis without summarizing the significance of STAS on other aspects. In this review, we comprehensively summarized the current literature related to STAS, so as to explore the clinical significance of STAS from multiple perspectives.

MAIN BODY

This section provided a comprehensive overview of the significance of STAS from multiple perspectives and summarized current controversies and challenges in the diagnosis and clinical application.

CONCLUSION

STAS is a conspicuous spreading phenomenon of lung cancers indicating worse prognosis; nevertheless, the treatment strategy for patients with STAS remains to be discussed. Further studies are needed to elaborate whether a STAS-positive patient who underwent limited resection needs a second operation or postoperative adjuvant treatment. Meanwhile, the internal mechanism of STAS formation is largely undiscovered. Whether the capability of detachment-migration-reattachment in STAS tumor cells is achieved at the time of primary tumorigenesis or in the progress of tumor development needs to be studied, and the related signal pathways or genetic alterations need to be explored. With this information, it may be possible to improve the prognosis of patients with STAS-positive lung cancers.

Relevance and prognostic ability of Twist, Slug and tumor spread through air spaces in lung adenocarcinoma

BACKGROUND

Tumor spread through air spaces (STAS) is a novel pathologic characteristic in lung adenocarcinomas that indicates invasive tumor behavior. We aimed to explore the relationship between Twist, Slug and STAS in lung adenocarcinoma and to investigate the potential relationship between epithelial-mesenchymal transition (EMT) and STAS.

MATERIALS AND METHODS

Our study retrospectively analyzed 115 patients with resected lung adenocarcinomas to evaluate the relationship between Twist, Slug and STAS. STAS was diagnosed using hematoxylin-eosin (H&E) staining. Immunohistochemistry was used to evaluate the expression levels of Slug and Twist.

RESULTS

In this study, 56 (48.7%) patients had STAS, 40 (34.8%) patients had Slug overexpression, and 28 (24.3%) patients had Twist overexpression. Patients with either STAS or Slug and Twist overexpression experienced poor recurrence-free survival (RFS) and overall survival (OS). There were significant associations between Twist overexpression, Slug overexpression and the presence of STAS. The logistic model further revealed that pathological stage, Twist overexpression and Slug overexpression were independent risk factors for STAS. A multivariate analysis that contained Twist, Slug, pathologic stage and STAS, showed that pathologic stage and STAS were independent prognostic factors for poor RFS and OS. Another multivariate model that contained Twist, Slug and pathologic stage, showed that pathologic stage, Twist overexpression and Slug overexpression were independent risk factors for poor RFS and OS. In the cohort with STAS, the multivariate analysis showed that pathologic stage and Twist overexpression were independent risk factors for poor survival. The subgroup analysis showed that patients with both Slug overexpression and Twist overexpression with STAS received a poor prognosis.

CONCLUSIONS

STAS, Slug and Twist were correlated with poor RFS and OS in resected lung adenocarcinomas. Additionally, STAS was correlated with the overexpression of Twist and Slug, which could potentially provide information on the mechanism of STAS.

Clinicopathologic Features and Genetic Alterations in Adenocarcinoma In Situ and Minimally Invasive Adenocarcinoma of the Lung: Long-Term Follow-Up Study of 121 Asian Patients

BACKGROUND

Adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) are both small tumors with good prognosis after surgical resection, and most of them present as ground glass opacities (GGOs) on computed tomography (CT) screening. However, the differences in clinicopathologic features and genetic alterations between AIS and MIA are poorly elaborated, and few studies have evaluated the prognosis of MIA with different invasive components. Meanwhile, the histological features of lung lesions presenting as unchanged pure GGOs are barely understood.

METHODS

Clinicopathologic features and genetic alterations of AIS (n = 59) and MIA (n = 62) presenting as GGOs were analyzed. Long-term preoperative observation (ranging from 2 to 1967 days) and postoperative follow-up (ranging from 0 to 92 months) was conducted.

RESULTS

The tumor size and consolidation/tumor ratio were significantly larger in the MIA cohort than those in the AIS cohort both on CT and microscopy images. Immunohistochemically, the expression of p53, Ki67, and cyclin D1 was higher in MIA than in AIS. The EGFR mutation rate was significantly higher in MIA, while other genetic alterations showed no differences. Six MIA cases showed recurrence or metachronous adenocarcinoma and all the cases with a predominant micropapillary invasive pattern demonstrated this feature.

CONCLUSIONS

The current CT measurements may be helpful in distinguishing AIS from MIA, but show limited utility in predicting the histology of unchanged pure GGOs. The invasive pattern may have an influence on the postoperative process of MIA; therefore, further studies are needed to evaluate the current diagnostic criteria and treatment strategy for MIA.

Advances In Research Of Spreading Through Air Spaces And The Effects On The Prognosis Of Lung Cancer

The concept of spread through air spaces (STAS) has been described as a new form of invasion in the lung in the 2015 WHO classification of Lung Tumors, namely invasion through alveolar spaces. STAS is a prognostic factor independent of growth pattern and tumor stage, and it is also an independent risk factor for unfavorable prognosis of stage I lung adenocarcinoma (ADC) and stage I lung squamous cell carcinoma (SCC). The pathological characteristics are different between ADC and SCC. STAS is not reported as routine, so setting a unified pathological reading standard, and hunting for STAS as a regular reading process is urgently advocated. We write this review to investigate the research progress of STAS and its effects on the prognosis of lung cancer.

Lymphadenectomy during pulmonary metastasectomy: Impact on survival and recurrence

Background and Objectives: Lymphadenectomy during pulmonary metastasectomy (PM) is widely carried out. We assessed the potential benefit on patient survival and tumor recurrence of this practice.

Methods: One hundred eighty‐one patients undergoing a first PM were studied. Eighty‐six patients (47.5%) underwent lymphadenectomy (L+ group) whereas 95 (52.5%) did not undergo nodal harvesting (L−group). Main outcomes were overall survival (OS) and disease‐free survival (DFS). Median follow‐up was 25 months (interquartile range [IQR], 13‐49).

Results: At follow‐up 84 patients (46.4%) died, whereas 97 (53.6%) were still alive with recurrence in 78 patients (43%). There was no difference in 5‐year survival (L+ 30.0% vs L− 43.2%; P = .87) or in the 5‐year cumulative incidence of recurrence (L + 63.2% vs L−80%; P = .07) between the two groups. Multivariable analysis indicated that disease‐free interval (DFI) less than 29 months (P < .001) and lung comorbidities (P = .003) were significant predictors of death. Metastases from non‐small–cell lung cancer increased the risk of lung comorbidities by a factor of 19.8, whereas the risk of DFI less than 29 months was increased nearly 11‐fold. Competing risk regression identified multiple metastases (P = .004), head/neck primary tumor (P = .009), and age less than 67 years (P = .024) as independent risk factors for recurrence.

Conclusion: Associated lymphadenectomy showed not to give any additional advantage in terms of survival and recurrence after PM.

Tumor Spread Through Air Spaces Is a Survival Predictor in Non-Small-Cell Lung Cancer

BACKGROUND

Tumor spread through air spaces (STAS) is a newly recognized invasion pattern in non-small-cell lung cancer (NSCLC). However, the clinical application value of STAS in NSCLC remains to be clarified. We aimed to comprehensively explore the potential role of STAS as a prognostic indicator in NSCLC.

PATIENTS AND METHODS

A systematic search was performed in PubMed, Embase, Cochrane Library, and Web of Science until April 15, 2018. A quantitative meta-analysis was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

A total of 3231 patients from 8 studies were included. STAS was observed in 1204 cases (37.3%). A significant association was found between STAS and poor progression-free survival (PFS) (hazard ratio [HR], 1.789; P < .001) and overall survival (OS; HR, 1.488; P < .001). STAS was also an independent prognostic factor for PFS (HR, 1.632; P < .001) and OS (HR, 1.475; P < .001) without obvious heterogeneity. Subgroup analyses and meta-regression showed histology type, tumor, node, metastases (TNM) stage, publication year, sample size, region, and quality score did not alter prognostic value of STAS. Tumor STAS was associated with male sex (P < .001), history of smoking (P < .001), tumor budding (P = .038), vascular invasion (P < .001), lymphatic invasion (P < .001), pleural invasion (P < .001), T stage (P < .001), N stage (P < .001), and TNM stage (P < .001). The publication bias was observed. After adjustment using a nonparametric "trim-and-fill" method, corrected HRs had no significant change.

CONCLUSION

Tumor STAS is associated with clinicopathologically aggressive features and could be exploited as a novel prognostic predictor in NSCLC.

Prevalence of ROS1 fusion in Chinese patients with non-small cell lung cancer

BACKGROUND

The study was conducted to investigate the clinicopathological features and prevalence of ROS1 gene fusion in Chinese patients with non-small cell lung cancer (NSCLC).

METHODS

The presence of ROS1 fusion was assessed by quantitative real-time PCR. Associations between ROS1 fusion and clinical characteristics were analyzed.

RESULTS

In total, 6066 patients with pathologically confirmed NSCLC and ROS1 fusion test results were enrolled. The average age was 60.89 ± 10.60 years and fusion was detected in 157 (2.59%) patients. Fusion frequency was significantly correlated with age, gender, smoking status (all P < 0.001), pathology type (P = 0.017), and lymph node metastasis stage (P = 0.027). ROS1 fusion-positive patients were significantly younger (55.68 ± 11.34 vs. negative 61.02 ± 10.44 years; P < 0.01). Fusion frequency was higher in women (3.71% vs. men 1.81%), never-smokers (3.33% vs. smokers 1.21%), and patients with adenocarcinoma (2.77% vs. squamous lung cancer 0.93%) and at advanced node stages (1.31%, 1.40%, 2.07%, and 3.23% for N0, N1, N2, and N3, respectively). No significant correlation between ROS1 fusion status and pathological stage was found in subgroups classified by pathological, tumor, or metastasis stage (P > 0.05). Age, smoking status, and lymph node stage were statistically significantly correlated with ROS1 fusion frequency (all P < 0.05); gender and pathology type were not significantly correlated with ROS1 fusion status after adjusting for smoking status.

CONCLUSION

An overall ROS1 fusion frequency of 2.59% was confirmed in this study. ROS1 fusion was more prevalent among younger patients, never-smokers, and those at advanced node stages.

Updates on Selected Topics in Lung Cancers: Air Space Invasion in Adenocarcinoma and Ki-67 Staining in Carcinoid Tumors

Context.—

Air space invasion or aerogenous spread of lung adenocarcinoma is a relatively new concept and has been implicated as a potential prognostic factor as well as has been added as an exclusion point in the diagnosis of minimally invasive adenocarcinoma. Potential role for Ki-67 immunostaining as a diagnostic and prognostic marker in pulmonary carcinoid tumors has been suggested in the literature, given the significant interobserver variability and the difficulty in predicting their clinical behavior.

Objective.—

To review the concept of air space invasion in lung adenocarcinoma and the current controversies regarding the role of Ki-67 immunostaining on pulmonary carcinoid tumors

Data Sources.—

PubMed search of English literature.

Conclusions.—

Pathologists need to recognize air space invasion with a critical evaluation to differentiate it from artifacts that are commonly seen in sections. Currently, Ki-67 immunostaining is not recommended for routine use in the diagnosis of pulmonary carcinoid tumors or for predicting their prognosis, except for the differential diagnosis from small cell carcinomas or large cell neuroendocrine carcinomas in small biopsy specimens with crush artifacts.

Tumor Spread Through Air Spaces Is an Independent Predictor of Recurrence-free Survival in Patients With Resected Lung Squamous Cell Carcinoma

Tumor spread through air spaces (STAS) is a newly recognized pattern of invasion in lung adenocarcinoma. However, clinical significance of STAS has not yet been characterized in lung squamous cell carcinoma. In this study, we investigated whether STAS could determine clinical outcome in Japanese patients with lung squamous cell carcinoma. We reviewed tumor slides from surgically resected lung squamous cell carcinomas (n=216). STAS was defined as tumor cells within air spaces in the lung parenchyma beyond the edge of the main tumor. Tumors were evaluated for histologic subtypes, tumor budding, and nuclear diameter. Recurrence-free survival (RFS) was analyzed using the log-rank test and the Cox proportional hazards model. Tumor STAS was observed in 87 patients (40%), increasing incidence with lymph node metastasis (P=0.037), higher pathologic stage (P=0.026), and lymphatic invasion (P=0.033). All cases with STAS showed a solid nest pattern. The 5-year RFS for patients with STAS was significantly lower than it was for patients without STAS in all patients (P=0.001) and in stage I patients (n=134; P=0.041). On multivariate analysis, STAS was an independent prognostic factor of a worse RFS (hazard ratio=1.61; P=0.023). Patients with STAS had a significantly increased risk of developing locoregional and distant recurrences (P=0.012 and 0.001, respectively). We found that tumor STAS was an independent predictor of RFS in patients with resected lung squamous cell carcinoma, and it was associated with aggressive tumor behavior.

Spread through Air Spaces (STAS) Is an Independent Predictor of Recurrence and Lung Cancer-Specific Death in Squamous Cell Carcinoma

INTRODUCTION

Spread through air spaces (STAS) is a recently recognized pattern of invasion in lung adenocarcinoma; however, it has not yet been characterized in squamous cell carcinoma (SCC).

METHODS

We reviewed 445 resected stage I to III lung SCCs and investigated the clinical significance of STAS. Cumulative incidence of recurrence and lung cancer-specific death were evaluated by competing risks analyses and overall survival by Cox models.

RESULTS

Of the total 445 patients, 336 (76%) were older than 65 years. Among the 273 patients who died, 91 (33%) died of lung cancer whereas the remaining ones died of competing events or unknown cause. STAS was observed in 132 patients (30%) and the frequency increased with stage. The cumulative incidences of any, distant, and locoregional recurrence as well as lung cancer-specific death were significantly higher in patients with STAS compared with in those without STAS, whereas there was no statistically significant difference in overall survival. In multivariable models for any recurrence and lung cancer-specific death, STAS was an independent predictor for both outcomes (p = 0.034 and 0.016, respectively).

CONCLUSION

STAS was present in one-third of resected lung SCCs. In competing risks analysis in a cohort in which three-fourths of the patients were elderly, STAS was associated with lung cancer-specific outcomes. Our findings suggest that STAS is one of the most prognostically significant histologic findings in lung SCC.

Correlation of Histologic Subtypes and Molecular Alterations in Pulmonary Adenocarcinoma: Therapeutic and Prognostic Implications

Major driver mutations of pulmonary adenocarcinomas have been identified and highlighted as actionable targets for precision cancer medicine. As phenotype is largely determined by genotype, genetic changes associated with morphologic features have recently received more attention from both pathologists and clinicians. The morphologic features of adenocarcinomas with mutations in EGFR or KRAS, or translocated ALK, have rarely been described. Pulmonary adenocarcinomas with EGFR mutations, the most common driver mutation encountered in Asian patients with pulmonary adenocarcinoma, show lepidic or papillary organotypic growth patterns. KRAS-mutated adenocarcinomas demonstrate nonorganotypic growth patterns, especially mucin-containing cells. P53 mutations are associated with aggressiveness rather than growth patterns. HER2 mutations are observed in mucinous adenocarcinoma and adenocarcinoma with micropapillary features. The histologic features of BRAF-mutated adenocarcinomas have not yet been established, but papillary, lepidic, solid, and acinar patterns have been observed. Adenocarcinomas with rearrangement of ALK, ROS1, and RET genes share similar histologic features, such as solid signet-ring cells and cribriform formation. However, adenocarcinomas with NRG1 rearrangements frequently show mucinous morphology. The histologic features and related mutations of adenocarcinomas with expression of programmed cell death-1 and programmed cell death ligands-1 may be helpful in guiding immunotherapeutic treatment. This review describes histopathologic features of adenocarcinomas and their correlation with molecular alterations.