Procedure-Specific Risk Prediction for Recurrence in Patients Undergoing Lobectomy or Sublobar Resection for Small (≤2 cm) Lung Adenocarcinoma: An International Cohort Analysis

Prognostic impact of mitosis and necrosis in non-mucinous lung adenocarcinomas and correlation with IASLC grading system

BACKGROUND

In 2020, the International Lung Cancer Study Group (IASLC) Pathology Committee established a grading system for non-mucinous primary lung adenocarcinomas. This grading system is based on whether areas of high-grade patterns are present in more than 20% of the tumor. Parameters, such as necrosis, mitotic activity, lymphovascular invasion (LVI) and spread through air spaces (STAS), are excluded from evaluating the grading system.

METHODS

A total of 217 patients' lung resection materials for primary lung adenocarcinoma were re-reviewed using the IASLC grading system. Necrosis, mitotic activity, LVI status and STAS were also evaluated in the resection materials, aiming to demonstrate the relationship between these histopathological features and clinical outcome data.

RESULTS

At all stages, overall survival (OS) and recurrence-free survival (RFS) were related to grade (p=0.011 and 0.024, respectively). Additionally, patients with necrosis were associated with worse OS and RFS (p=0.002 and 0.048, respectively). When grade 2 and 3 tumors were analyzed individually, a significant relationship was found between necrosis and OS in grade 3 tumors (p=0.002). Patients with a high mitotic count (≥10/10 high-power fields) had significantly worse OS (p=0.046). The prevalence of LVI and STAS increased with grade; however, their prognostic significance has not been demonstrated.

CONCLUSIONS

The new grading system provides a highly efficient prognostic classification for survival. Necrosis and high mitotic count are important prognostic parameters for survival. Additionally, necrosis is a stage-independent prognostic factor for OS in grade 3 tumors, although no effect on prognosis can be demonstrated in grade 2 tumors.

Mean computed tomography value to predict spread through air spaces in clinical N0 lung adenocarcinoma

BACKGROUND

The aim of this study was to assess the ability of radiologic factors such as mean computed tomography (mCT) value, consolidation/tumor ratio (C/T ratio), solid tumor size, and the maximum standardized uptake (SUVmax) value by F-18 fluorodeoxyglucose positron emission tomography to predict the presence of spread through air spaces (STAS) of lung adenocarcinoma.

METHODS

A retrospective study was conducted on 118 patients those diagnosed with clinically without lymph node metastasis and having a pathological diagnosis of adenocarcinoma after undergoing surgery. Receiver operating characteristics (ROC) analysis was used to assess the ability to use mCT value, C/T ratio, tumor size, and SUVmax value to predict STAS. Univariate and multiple logistic regression analyses were performed to determine the independent variables for the prediction of STAS.

RESULTS

Forty-one lesions (34.7%) were positive for STAS and 77 lesions were negative for STAS. The STAS positive group was strongly associated with a high mCT value, high C/T ratio, large solid tumor size, large tumor size and high SUVmax value. The mCT values were - 324.9 ± 19.3 HU for STAS negative group and - 173.0 ± 26.3 HU for STAS positive group (p < 0.0001). The ROC area under the curve of the mCT value was the highest (0.738), followed by SUVmax value (0.720), C/T ratio (0.665), solid tumor size (0.649). Multiple logistic regression analyses using the preoperatively determined variables revealed that mCT value (p = 0.015) was independent predictive factors of predicting STAS. The maximum sensitivity and specificity were obtained at a cutoff value of - 251.8 HU.

CONCLUSIONS

The evaluation of mCT value has a possibility to predict STAS and may potentially contribute to the selection of suitable treatment strategies.

Preoperative nomogram for predicting spread through air spaces in clinical-stage IA non-small cell lung cancer using 18F-fluorodeoxyglucose positron emission tomography/computed tomography

PURPOSE

This study aims to assess the predictive value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) radiological features and the maximum standardized uptake value (SUVmax) in determining the presence of spread through air spaces (STAS) in clinical-stage IA non-small cell lung cancer (NSCLC).

METHODS

A retrospective analysis was conducted on 180 cases of NSCLC with postoperative pathological assessment of STAS status, spanning from September 2019 to September 2023. Of these, 116 cases from hospital one comprised the training set, while 64 cases from hospital two formed the testing set. The clinical information, tumor SUVmax, and 13 related CT features were analyzed. Subgroup analysis was carried out based on tumor density type. In the training set, univariable and multivariable logistic regression analyses were employed to identify the most significant variables. A multivariable logistic regression model was constructed and the corresponding nomogram was developed to predict STAS in NSCLC, and its diagnostic efficacy was evaluated in the testing set.

RESULTS

SUVmax, consolidation-to-tumor ratio (CTR), and lobulation sign emerged as the best combination of variables for predicting STAS in NSCLC. Among these, SUVmax and CTR were identified as independent predictors for STAS prediction. The constructed prediction model demonstrated area under the curve (AUC) values of 0.796 and 0.821 in the training and testing sets, respectively. Subgroup analysis revealed a 2.69 times higher STAS-positive rate in solid nodules compared to part-solid nodules. SUVmax was an independent predictor for predicting STAS in solid nodular NSCLC, while CTR and an emphysema background were independent predictors for STAS in part-solid nodular NSCLC.

CONCLUSION

Our nomogram based on preoperative 18F-FDG PET/CT radiological features and SUVmax effectively predicts STAS status in clinical-stage IA NSCLC. Furthermore, our study highlights that metabolic parameters and CT variables associated with STAS differ between solid and part-solid nodular NSCLC.

The value of high-risk clinicopathologic features for chemotherapy in stage I non-small cell lung cancer: a propensity score-matched study

Background

Surgical resection is the main treatment for early-stage non-small cell lung cancer (NSCLC), but recurrence remains a concern. Adjuvant chemotherapy has been shown to have survival benefits for resected stage II and III NSCLC, but debate continues regarding its use in stage I NSCLC. High-risk features, such as tumor size and stage, are considered in deciding whether to administer adjuvant chemotherapy.

Methods

The data of 666,689 patients diagnosed with lung cancer from 2004 to 2016 were collected from the Surveillance, Epidemiology, and End Results database. Ultimately, 26,160 patients diagnosed with stage I NSCLC were included in the study based on a screening procedure.

Results

After matching, 4,285 patients were identified, of whom 1,440 (33.6%) received chemotherapy. High-risk clinicopathologic features, including a high histologic grade, visceral pleural invasion (VPI), the examination of an insufficient number of lymph nodes (LNs), and limited resection, were independent risk factors for a poor prognosis. Chemotherapy significantly improved lung cancer-specific survival (LCSS) and overall survival (OS) in stage I patients with VPI [LCSS: hazard ratio (HR): 0.839, 95% confidence interval (CI): 0.706-0.998, P=0.047; OS: HR: 0.711, 95% CI: 0.612-0.826, P<0.001], regardless of whether or not the patient had fewer than 11 LNs (LCSS: HR: 0.809, 95% CI: 0.664-0.986, P=0.04; OS: HR: 0.677, 95% CI: 0.570-0.803, P<0.001). Chemotherapy was only observed to improve OS for stage IB patients with a high histologic grade when combined with either or both of the following high-risk factors: the presence of VPI and fewer than 11 LNs examined.

Conclusions

The presence of VPI was the dominant predictor and the examination of an insufficient number of LNs was the secondary indicator, and a high histologic grade was a potential indicator of the need to administer chemotherapy in the treatment of stage I NSCLC.

The International Association for the Study of Lung Cancer (IASLC) Staging Project for Lung Cancer: Recommendation to Introduce Spread Through Air Spaces as a Histologic Descriptor in the Ninth Edition of the TNM Classification of Lung Cancer. Analysis of 4061 Pathologic Stage I NSCLC

INTRODUCTION

Spread through air spaces (STAS) consists of lung cancer tumor cells that are identified beyond the edge of the main tumor in the surrounding alveolar parenchyma. It has been reported by meta-analyses to be an independent prognostic factor in the major histologic types of lung cancer, but its role in lung cancer staging is not established.

METHODS

To assess the clinical importance of STAS in lung cancer staging, we evaluated 4061 surgically resected pathologic stage I R0 NSCLC collected from around the world in the International Association for the Study of Lung Cancer database. We focused on whether STAS could be a useful additional histologic descriptor to supplement the existing ones of visceral pleural invasion (VPI) and lymphovascular invasion (LVI).

RESULTS

STAS was found in 930 of 4061 of the pathologic stage I NSCLC (22.9%). Patients with tumors exhibiting STAS had a significantly worse recurrence-free and overall survival in both univariate and multivariable analyses involving cohorts consisting of all NSCLC, specific histologic types (adenocarcinoma and other NSCLC), and extent of resection (lobar and sublobar). Interestingly, STAS was independent of VPI in all of these analyses.

CONCLUSIONS

These data support our recommendation to include STAS as a histologic descriptor for the Ninth Edition of the TNM Classification of Lung Cancer. Hopefully, gathering these data in the coming years will facilitate a thorough analysis to better understand the relative impact of STAS, LVI, and VPI on lung cancer staging for the Tenth Edition TNM Stage Classification.

Vascular invasion predicts the subgroup of lung adenocarcinomas ≤2.0 cm at risk of poor outcome treated by wedge resection compared to lobectomy

Background

Recent randomized control trials (JCOG0802 and CALGB140503) have shown sublobar resection to be noninferior to lobectomy for non-small cell lung cancer (NSCLC) ≤2.0 cm. We have previously proposed histologic criteria stratifying lung adenocarcinoma into indolent low malignant potential (LMP) and aggressive angioinvasive adenocarcinomas, resulting in better prognostication than provided by World Health Organization grade. Here we determine whether pathologic classification is reproducible and whether subsets of adenocarcinomas predict worse outcomes when treated by wedge resection compared to lobectomy.

Methods

A retrospective cohort of 108 recipients of wedge resection and 187 recipients of lobectomy for stage I/0 lung adenocarcinomas ≤2.0 cm was assembled from 2 institutions. All tumors were classified by a single pathologist, and interobserver reproducibility was assessed in a subset (n = 92) by 5 pathologists.

Results

Angioinvasive adenocarcinoma (21%-27% of cases) was associated with worse outcomes when treated with wedge resection compared to lobectomy (5-year recurrence-free survival, 57% vs 85% [P = .007]; 5-year disease-free survival [DSS], 70% vs 90% [P = .043]; 7-year overall survival, 37% vs 58% [P = .143]). Adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and LMP exhibited 100% 5-year DSS regardless of the surgical approach. Multivariable analysis showed that angioinvasion, tumor size, margin status, and extent of nodal sampling were significantly associated with recurrence but not with surgical procedure. There was substantial interobserver reproducibility among the pathologists for the diagnosis of angioinvasive adenocarcinoma (κ = 0.71) and the combined indolent AIS/MIA/LMP group (κ = 0.74).

Conclusions

The majority (∼75%) of lung adenocarcinomas ≤2 cm are adequately managed with wedge resection; however, angioinvasive adenocarcinomas (∼25%) treated by wedge resection with suboptimal nodal sampling exhibit poor outcomes, with a 40% to 45% rate of recurrence within 5 years and 60% to 65% overall mortality at 7 years.

Preoperative 18F-FDG PET/CT and CT radiomics for identifying aggressive histopathological subtypes in early stage lung adenocarcinoma

Lung adenocarcinoma (ADC) is the most common non-small cell lung cancer. Surgical resection is the primary treatment for early-stage lung ADC while lung-sparing surgery is an alternative for non-aggressive cases. Identifying histopathologic subtypes before surgery helps determine the optimal surgical approach. Predominantly solid or micropapillary (MIP) subtypes are aggressive and associated with a higher likelihood of recurrence and metastasis and lower survival rates. This study aims to non-invasively identify these aggressive subtypes using preoperative 18F-FDG PET/CT and diagnostic CT radiomics analysis. We retrospectively studied 119 patients with stage I lung ADC and tumors ≤ 2 cm, where 23 had aggressive subtypes (18 solid and 5 MIPs). Out of 214 radiomic features from the PET/CT and CT scans and 14 clinical parameters, 78 significant features (3 CT and 75 PET features) were identified through univariate analysis and hierarchical clustering with minimized feature collinearity. A combination of Support Vector Machine classifier and Least Absolute Shrinkage and Selection Operator built predictive models. Ten iterations of 10-fold cross-validation (10 ×10-fold CV) evaluated the model. A pair of texture feature (PET GLCM Correlation) and shape feature (CT Sphericity) emerged as the best predictor. The radiomics model significantly outperformed the conventional predictor SUVmax (accuracy: 83.5% vs. 74.7%, p = 9e-9) and identified aggressive subtypes by evaluating FDG uptake in the tumor and tumor shape. It also demonstrated a high negative predictive value of 95.6% compared to SUVmax (88.2%, p = 2e-10). The proposed radiomics approach could reduce unnecessary extensive surgeries for non-aggressive subtype patients, improving surgical decision-making for early-stage lung ADC patients.

The Value of Micro-CT in the Diagnosis of Lung Carcinoma: A Radio-Histopathological Perspective

Micro-computed tomography (micro-CT) is a relatively new imaging modality and the three-dimensional (3D) images obtained via micro-CT allow researchers to collect both quantitative and qualitative information on various types of samples. Micro-CT could potentially be used to examine human diseases and several studies have been published on this topic in the last decade. In this study, the potential uses of micro-CT in understanding and evaluating lung carcinoma and the relevant studies conducted on lung and other tumors are summarized. Currently, the resolution of benchtop laboratory micro-CT units has not reached the levels that can be obtained with light microscopy, and it is not possible to detect the histopathological features (e.g., tumor type, adenocarcinoma pattern, spread through air spaces) required for lung cancer management. However, its ability to provide 3D images in any plane of section, without disturbing the integrity of the specimen, suggests that it can be used as an auxiliary technique, especially in surgical margin examination, the evaluation of tumor invasion in the entire specimen, and calculation of primary and metastatic tumor volume. Along with future developments in micro-CT technology, it can be expected that the image resolution will gradually improve, the examination time will decrease, and the relevant software will be more user friendly. As a result of these developments, micro-CT may enter pathology laboratories as an auxiliary method in the pathological evaluation of lung tumors. However, the safety, performance, and cost effectiveness of micro-CT in the areas of possible clinical application should be investigated. If micro-CT passes all these tests, it may lead to the convergence of radiology and pathology applications performed independently in separate units today, and the birth of a new type of diagnostician who has equal knowledge of the histological and radiological features of tumors.

A CT-Based Radiomics Nomogram Combined with Clinic-Radiological Characteristics for Preoperative Prediction of the Novel IASLC Grading of Invasive Pulmonary Adenocarcinoma

RATIONALE AND OBJECTIVES

The novel International Association for the Study of Lung Cancer (IASLC) grading system of invasive lung adenocarcinoma (ADC) demonstrated a remarkable prognostic effect and enabled numerous patients to benefit from adjuvant chemotherapy. We sought to build a CT-based nomogram for preoperative prediction of the IASLC grading.

MATERIALS AND METHODS

This work retrospectively analyzed the CT images and clinical data of 303 patients with pathologically confirmed invasive ADC. The histological subtypes and radiological characteristics of the patients were re-evaluated. Radiomics features were extracted, and the optimal subset of features was established by ANOVA, spearman correlation analysis, and the least absolute shrinkage and selection operator (LASSO). Univariate and multivariate analyses identified the independent clinical and radiological variables. Finally, multivariate logistic regression analysis incorporated clinical, radiological, and optimal radiomics features into the nomogram. Receiver operating characteristic (ROC) curve, and accuracy were applied to assess the model's performance. Decision curve analysis (DCA), and calibration curve were applied to assess the clinical usefulness.

RESULTS

Nine selected CT image features were used to develop the radiomics model. The accuracy, precision, sensitivity, and specificity of the radiomics model outperformed the clinic-radiological model in the training and testing sets. Integrating Radscore with independent radiological characteristics showed higher prediction performance than clinic-radiological characteristics alone in the training (AUC, 0.915 vs. 0.882; DeLong, p < 0.05) and testing (AUC, 0.838 vs. 0.782; DeLong, p < 0.05) sets. Good calibration and decision curve analysis demonstrated the clinical usefulness of the nomogram.

CONCLUSION

Radiomics features effectively predict high-grade ADC. The combined nomogram may facilitate selecting patients who benefit from adjuvant treatment.

Evolutionary characterization of lung adenocarcinoma morphology in TRACERx

Lung adenocarcinomas (LUADs) display a broad histological spectrum from low-grade lepidic tumors through to mid-grade acinar and papillary and high-grade solid, cribriform and micropapillary tumors. How morphology reflects tumor evolution and disease progression is poorly understood. Whole-exome sequencing data generated from 805 primary tumor regions and 121 paired metastatic samples across 248 LUADs from the TRACERx 421 cohort, together with RNA-sequencing data from 463 primary tumor regions, were integrated with detailed whole-tumor and regional histopathological analysis. Tumors with predominantly high-grade patterns showed increased chromosomal complexity, with higher burden of loss of heterozygosity and subclonal somatic copy number alterations. Individual regions in predominantly high-grade pattern tumors exhibited higher proliferation and lower clonal diversity, potentially reflecting large recent subclonal expansions. Co-occurrence of truncal loss of chromosomes 3p and 3q was enriched in predominantly low-/mid-grade tumors, while purely undifferentiated solid-pattern tumors had a higher frequency of truncal arm or focal 3q gains and SMARCA4 gene alterations compared with mixed-pattern tumors with a solid component, suggesting distinct evolutionary trajectories. Clonal evolution analysis revealed that tumors tend to evolve toward higher-grade patterns. The presence of micropapillary pattern and 'tumor spread through air spaces' were associated with intrathoracic recurrence, in contrast to the presence of solid/cribriform patterns, necrosis and preoperative circulating tumor DNA detection, which were associated with extra-thoracic recurrence. These data provide insights into the relationship between LUAD morphology, the underlying evolutionary genomic landscape, and clinical and anatomical relapse risk.

Clinicopathological features and prognostic impact of dirty necrosis in metastatic lung cancers from the colon and rectum

Dirty necrosis (DN) is a form of tumor necrosis (TN) with prominent neutrophil infiltration and cell detritus in the necrotic foci. This study aimed to characterize the clinicopathological features of DN in metastatic lung cancers of the colon and rectum (MLCRs). A total of 227 patients who underwent pulmonary metastasectomy and complete resection for MLCR were included in this study. TN was evaluated using digitally scanned resection specimens. These slides were immunostained for biomarkers of NETosis (citrullinated histone H3 [citH3] and myeloperoxidase [MPO]), and the area positive for citH3 and MPO was further quantified. TN was observed in 216 cases (95.2%), and 54 (25.0%) of these cases had DN. The presence of TN was not associated with a worse prognosis; however, patients with DN had a significantly shorter overall survival than those without DN (p < 0.01). Furthermore, the presence of DN was a poor prognostic factor in both the univariate and multivariate analyses. Immunohistochemical analysis revealed that the percentage of citH3-positive and MPO-positive areas in the DN-positive cases was significantly higher than that in the DN-negative cases (p < 0.01 and p < 0.01, respectively). In surgically resected MLCR, DN is the characteristic TN subtype associated with poor prognosis and neutrophil extracellular traps (NETs).

Identification of Grb2-associated binding protein 3 expression to predict clinical outcomes and immunotherapeutic responses in lung adenocarcinoma

With the deepening research on tumor microenvironment (TME), immunotherapy has been deemed to be one of the major breakthroughs for cancer therapy. Nevertheless, only some patients respond well to this treatment. It is vital to explore predictive biomarkers for clinical benefit of immunotherapy. Grb2-associated binding protein 3 (GAB3) exerts essential biological functions in ovarian cancer and colorectal cancer. The potential role of GAB3 in lung adenocarcinoma (LUAD) has not been fully elucidated. RNA-sequencing data, genetic mutation data, and matched clinical data were obtained from the cancer genome atlas (TCGA) databases, then underwent gene expression, prognosis, enrichment, TME, immune checkpoint blockade (ICB) response analyses utilizing R packages. The mRNA expression level of GAB3 was dramatically decreased in LUAD, and the prognostic analysis indicated that the patients with low GAB3 expression performed unsatisfactory clinical outcomes. In addition, differentially expressed genes (DEGs) and subsequent functional enrichment analysis demonstrated that GAB3 was primarily connected with T cell activation and immune response. Finally, GAB3 expression positively correlated with immune infiltrates and immune checkpoint genes, and therapeutic effect of ICB. In summary, our study comprehensively uncovers that GAB3 may function as a promising biomarker to predict clinical outcomes and immunotherapeutic responses in LUAD patients.

Clinicopathological Impact of the Spread through Air Space in Non-Small Cell Lung Cancer: A Meta-Analysis

This study aimed to elucidate the clinicopathological significance of spread through air space (STAS) in non-small cell lung cancer (NSCLC) through a meta-analysis. Using 47 eligible studies, we obtained the estimated rates of STAS in various histological subtypes of NSCLC and compared the clinicopathological characteristics and prognosis between NSCLC with and without STAS. The estimated STAS rate was 0.368 (95% confidence interval [CI], 0.336–0.0.401) in patients with NSCLC. Furthermore, the STAS rates for squamous cell carcinoma and adenocarcinoma were 0.338 (95% CI, 0.273–0.411) and 0.374 (95% CI, 0.340–0.409), respectively. Among the histological subtypes of adenocarcinoma, micropapillary-predominant tumors had the highest rate of STAS (0.719; 95% CI, 0.652–0.778). The STAS rates of solid- and papillary-predominant adenocarcinoma were 0.567 (95% CI, 0.478–0.652) and 0.446 (95% CI, 0.392–0.501), respectively. NSCLCs with STAS showed a higher visceral pleural, venous, and lymphatic invasion than those without STAS. In addition, anaplastic lymphoma kinase mutations and ROS1 rearrangements were significantly more frequent in NSCLCs with STAS than in those without STAS. The presence of STAS was significantly correlated with worse overall and recurrence-free survival (hazard ratio, 2.119; 95% CI, 1.811–2.480 and 2.372; 95% CI, 2.018–2.788, respectively). Taken together, the presence of STAS is useful in predicting the clinicopathological significance and prognosis of patients with NSCLC.

Recurrence dynamics after curative surgery in patients with invasive mucinous adenocarcinoma of the lung

Background

We investigated the patterns and timing of recurrence and death as well as prognostic factors based on clinicopathological and radiological factors in patients who underwent surgical treatment for invasive mucinous adenocarcinoma (IMA).

Methods

We reviewed clinicopathological findings including spread through air spaces (STAS) and CT findings of IMA such as morphology, solidity, margin, well-defined heterogeneous ground-glass opacity, CT angiogram, and air bronchogram signs from 121 consecutive patients who underwent surgical resection. Prognostic factors for disease-free survival (DFS) and overall survival (OS) were identified. Hazard rate analyses were performed for the survival dynamics.

Results

T stage (hazard ratio [HR] = 4.102, p = 0.03), N stage (N2 vs. N0, HR = 7.653, p < 0.001), and consolidative CT morphology (HR = 3.556, p = 0.008) remained independent predictors for DFS. Age (HR = 1.110, p = 0.002), smoking (HR = 12.893, p < 0.001), T stage (HR = 13.005, p = 0.006), N stage (N2 vs. N0, HR = 7.653, p = 0.004), STAS (HR = 7.463, p = 0.008), and consolidative CT morphology (HR = 6.779, p = 0.007) remained independent predictors for OS. Consolidative morphology, higher T and N stage, and presence of STAS revealed initial sharp peaks after steep decline of the hazard rate curves for recurrence or death in follow-up period.

Conclusions

Consolidative morphology, higher T and N stage, smoking, and STAS were indicators of significantly greater risk of early recurrence or death in patients with IMA. Thus, these findings could be incorporated into future surveillance strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13244-022-01208-5.

The prognostic significance of tumor spread through air space in stage I lung adenocarcinoma

Aim

There are still patients of stage I lung adenocarcinoma (ADC) suffering from local or distant recurrence. Herein we conducted a meta‐analysis to investigate the prognostic value of tumor spread through air space (STAS), a new form of invasion pattern, in patients with pathologically confirmed stage I lung ADC.

Methods

Related literature was searched using PubMed, Embase, Cochrane Library, and Web of Science databases from the inception dates to September 4, 2021. Recurrence‐free survival (RFS) and overall survival (OS) were set as primary outcome endpoints. In addition, subgroup analyses on operation mode, edition of the American Joint Committee on Cancer TNM staging, sample size, and research regions were also investigated.

Results

A total of 17 studies involving 9785 patients were included. The presence of STAS was detected in 31.2% of patients and was associated with poor RFS (adjusted hazard ratio [HR] = 1.93, p < 0.001) and OS (HR = 2.02, p < 0.001). In subgroup analysis on operation mode, the prognostic value of STAS was prominently shown in patients who underwent limited resection (RFS: HR = 3.58, p < 0.001; OS: HR = 3.37, p < 0.001), while for patients who underwent lobectomy, adverse impact of STAS on RFS was observed (HR = 1.60, p = 0.019), but no significant difference was observed on OS (HR = 1.56, p = 0.061). The results fluctuated in different regions while other factors did not alter the independent predictive value of STAS.

Conclusion

Tumor STAS should be considered as an adverse prognostic indicator for patients with stage I lung ADC, especially for those under limited resection. More intensive medical care for those patients needs to be investigated in further studies.

Bibliometric Analysis of 50 Most Cited Articles Comparing Lobectomy with Sublobar Resection

BACKGROUND

 Recent years have seen an increase in the number of studies of the sublobar resection approach in non-small cell lung cancer (NSCLC) surgery. The purpose of this bibliometric analysis is to assess the significance and impact of articles comparing sublobar resection and lobectomy in NSCLC surgery.

MATERIAL AND METHODS

 The Web of Science database was searched to identify studies comparing sublobar resection and lobectomy in NSCLC surgery published between 2005 and 2020 (accessed: September 11, 2020). The 50 most cited articles were analyzed by years, countries, authors, authors' affiliations, journals, journals' addresses, and impact factors.

RESULTS

 The bibliometric analysis revealed that the most cited article had 443 citations, while the total number of citations of all articles was 2,820. The mean number of citations, in turn, was 56.4 ± 75.62 (1-443) times. The highest number of publications over the past 15 years was in 2016, with eight articles. The Annals of Thoracic Surgery (n = 10; 20%) had the highest number of publications on the list. The articles included in the present study were mostly (n = 35, 70%) published in U.S. journals. While multiple subject matters and analyses were presented by many studies, survival was the topic of greatest interest, with 37 (74%) studies.

CONCLUSION

 This study revealed that interest in studies comparing sublobar resection with lobectomy has increased in recent years. It also presents both quantitative and qualitative analyses of the most cited articles in the literature on this topic. Therefore, it can serve as a guide for researchers.

Spread through air spaces positivity and extent of resection in patients with Stage I non-small cell lung cancer: A contemporary review

The concept of spread through air spaces is a type of cancer spread that is unique to lung and may be established as a criterion for invasion. It is a potential risk factor for recurrence and poor prognosis in patients with early-stage non-small cell lung cancer. This review provides a contemporary overview on recent data in this field and aim to help surgeons to decide the extent of resection according to patients" spread through air spaces status.

The 2021 WHO Classification of Lung Tumors: Impact of advances since 2015

The 2021 World Health Organisation (WHO) Classification of Thoracic Tumours was published earlier this year, with classification of lung tumors being one of the chapters. The principles remain those of using morphology first, supported by immunohistochemistry and then molecular techniques. In 2015, there was particular emphasis on using immunohistochemistry to make classification more accurate. In 2021, there is greater emphasis throughout the book on advances in molecular pathology across all tumor types. Major features within this edition are 1) broader emphasis on genetic testing than in the 2015 WHO Classification, 2) a chapter entirely dedicated to the classification of small diagnostic samples, 3) continued recommendation to document percentages of histological patterns in invasive non-mucinous adenocarcinomas, with utilization of these features to apply a formal grading system, as well as using only invasive size for T-factor size determination in part lepidic non-mucinous lung adenocarcinomas as recommended by the 8^th Edition TNM Classification, 4) recognition of spread through airspaces (STAS) as a histological feature with prognostic significance, 5) moving lymphoepithelial carcinoma to squamous cell carcinomas, 6) update on evolving concepts in lung neuroendocrine neoplasm classification, 7) recognition of bronchiolar adenoma/ciliated muconodular papillary tumor (BA/CMPT) as a new entity within the adenoma subgroup, 8) recognition of thoracic SMARCA4-deficient undifferentiated tumor, and 9) inclusion of essential and desirable diagnostic criteria for each tumor.

Spread Through Air Spaces (STAS) in Non-Small Cell Lung Carcinoma: Evidence Supportive of an In Vivo Phenomenon

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.

Meta-analysis of Lobectomy and Sublobar Resection for Stage I Non-small Cell Lung Cancer With Spread Through Air Spaces

Surgery is the preferred treatment for early-stage non-small cell lung cancer (NSCLC). Numerous studies have shown that spread through air spaces (STAS) can predict the survival of patients with stage I NSCLC. However, for stage I NSCLC, it is not known whether sublobar resection or lobectomy should be performed if STAS is present. In the present study, we compared the survival outcomes of patients with STAS who underwent lobectomy versus those who underwent sublobar resection. A search was performed on the PubMed, Cochrane Library and EMBASE on March 6, 2021 to identify relevant studies. Predetermined criteria were utilized to screen studies. A meta-analysis was performed using hazard ratio (HR). In total, 13 studies involving 5947 patients were included in the meta-analysis. It was found that STAS was significantly correlated with worse RFS (HR = 2.58, 95% CI: 2.16-3.07) and OS (HR = 2.41, 95% CI: 1.97-2.95) in patients with stage I NSCLC. Lobectomy resulted in a longer RFS (HR = 2.59, 95% CI: 1.99-3.37) and OS (HR = 2.78, 95% CI: 1.92-4.02) than sublobar resection in stage I NSCLC patients with STAS. STAS is an independent prognostic factor in NSCLC. Lobectomy may be more effective for stage I NSCLC patients who underwent sublobar resection previously if STAS is present.

Radiomic values from high-grade subtypes to predict spread through air spaces in lung adenocarcinoma

BACKGROUND

We aimed to establish a radiomic prediction model for tumor spread through air spaces (STAS) in lung adenocarcinoma using radiomic values from high-grade subtypes (solid and micropapillary).

METHODS

We retrospectively reviewed 327 patients with lung adenocarcinoma from two institutes (Cohort 1: 227 patients; Cohort 2: 100 patients) between March 2017 and March 2019. STAS was identified in 113 (34.6%) patients. A high-grade likelihood prediction model was constructed based on a historical cohort of 82 patients with "near-pure" pathological subtype. The STAS prediction model based on the patch-wise mechanism identified the high-grade likelihood area for each voxel within the internal border of the tumor. STAS presence was indirectly predicted by a volume percentage threshold of the high-grade likelihood area. Performance was evaluated by receiver operating curve analysis with 10-repetition, 3-fold cross-validation in Cohort 1, and was individually tested in Cohort 2.

RESULTS

Overall, 227 patients (STAS-positive: 77 [33.9%]) were enrolled for cross-validation (Cohort 1) while 100 (STAS-positive: 36 [36.0%]) underwent individual testing (Cohort 2). The gray level co-occurrence matrix (variance) and histogram (75^th percentile) features were selected to construct the high-grade likelihood prediction model, which was used as the STAS prediction model. The proposed model achieved good performance in Cohort 1 with an area under the curve, sensitivity, and specificity, of 81.44%, 86.75%, and 62.60%, respectively, and correspondingly, in Cohort 2, they were 83.16%, 83.33%, and 63.90%, respectively.

CONCLUSIONS

The proposed computed tomography-based radiomic prediction model could help guide preoperative prediction of STAS in early-stage lung adenocarcinoma and relevant surgeries.

Histopathologic features from preoperative biopsies to predict spread through air spaces in early-stage lung adenocarcinoma: a retrospective study

Background

Although spread through air spaces (STAS) is a robust biomarker in surgically resected lung cancer, its application to biopsies is challenging. Moreover, limited resection is not an effective treatment for STAS-positive lung adenocarcinoma. This study aimed to identify histologic features from preoperative percutaneous transthoracic needle biopsies (PTNBs) to predict STAS status in the subsequently resected specimens, and thus help in selecting the surgical extent.

Methods

Between January 2014 and December 2015, 111 PTNB specimens and subsequent resection specimens from consecutive lung adenocarcinoma patients were retrospectively examined. Histopathologic features of PTNB specimens and presence of STAS in subsequent resection specimens were evaluated and correlations between them were analyzed statistically.

Results

The study participants had a mean age of 59 years (range, 35–81) and included 50 men and 61 women. Thirty-six patients were positive for STAS whereas 75 were negative. The micropapillary/solid histologic subtypes of lung adenocarcinoma (26 of 39; 66.7%; P <  0.001), necrotic/tumor debris (31 of 42; 73.8%; P <  0.001), intratumoral budding (ITB) (20 of 33; 60.6%; P <  0.001), desmoplasia (35 of 41; 85.4%; P <  0.001), and grade 3 nuclei (12 of 14; 85.7%; P <  0.001) were more common in STAS-positive tumors. Micropapillary/solid histologic subtype (OR, 1.35; 95% CI: 1.06, 1.67), ITB (OR, 1.64; 95% CI: 1.09, 2.83), desmoplasia (OR, 1.83; 95% CI: 1.36, 3.12), and N stage (N1 stage: OR, 1.37; 95% CI: 1.19, 1.87) (N2 stage: OR, 1.29; 95% CI: 1.07, 1.73) were independent predictors of STAS.

Conclusions

Micropapillary/solid histologic subtype, ITB, and desmoplasia in preoperative PTNB specimens were independently associated with STAS in the subsequent resection specimens. Therefore, these can predict STAS and may help to optimize therapeutic planning.

Clinicopathological, gene expression and genetic features of stage I lung adenocarcinoma with necrosis

OBJECTIVES

The purpose of this study was to investigate the clinicopathological, gene expression and genetic features of stage I lung adenocarcinoma with necrosis.

METHODS

We retrospectively reviewed 521 cases with pathologic stage I lung adenocarcinoma resected by lobectomy and lymph node dissection. We calculated the ratio of tumor necrotic area by digital image analysis and investigated the relationship between tumor necrosis and prognosis. Furthermore, we analyzed the differentially expressed genes between cases with and without necrosis using The Cancer Genome Atlas Lung Adenocarcinoma (TCGA-LUAD) dataset. Using whole exon sequencing data (n = 97), we examined whether tumor necrosis correlates with single nucleotide variants (SNVs) and driver mutations.

RESULTS

Eighty four (16%) cases of the study cohort had tumor necrosis. The presence of necrosis significantly correlated with poorer prognosis (5-year overall survival: 91.9% vs. 75.4%, p < 0.001; 5-year recurrence-free survival: 86.0% vs. 59.0%, p < 0.001); however, the ratio of necrotic area did not correlate with prognosis. In multivariable analysis, invasive component size, vascular invasion, and tumor necrosis were independently associated with a higher risk of recurrence (hazard ratio, 1.652; 95% confidence interval, 1.033-2.641; p = 0.036). Gene expression analysis of TCGA stage I lung adenocarcinoma revealed enrichment of biological processes, such as cell cycle and response to hypoxia, in cases with necrosis. The cases with tumor necrosis had more SNVs than those without tumor necrosis (p = 0.027), especially in smokers.

CONCLUSION

Stage I lung adenocarcinoma with tumor necrosis has worse prognosis than that without, and has distinctclinicopathological features in terms of gene expression and genetic features.

Is There a Role for Percutaneous Ablation for Early Stage Lung Cancer? What Is the Evidence?

PURPOSE OF REVIEW

For patients with early stage non-small-cell lung cancer (NSCLC), thermal ablation (TA) has become in the least two decades an option of treatment used worldwide for patients with comorbidities who are not surgical candidates. Here, we review data published with different TA techniques: radiofrequency ablation (RFA), microwave ablation (MWA) and cryoablation. This paper reviews also the comparison that has been made between TA and stereotactic radiotherapy (SBRT).

RECENT FINDINGS

A majority of retrospective studies, the absence of comparative studies, and the variety of techniques make difficult to get evident data. Nevertheless, these stand-alone techniques have demonstrated local efficacy for tumors less than 3 cm and good tolerance on fragile patients. Many recent reviews and database analyses show that outcomes after TA (mainly RFA and MWA) are comparable to SBRT in terms of survival rates. For patients who are unfit for surgery, TA has demonstrated interesting results for safety, benefits in overall survival, and acceptable local control.

Tumor Margin Contains Prognostic Information: Radiomic Margin Characteristics Analysis in Lung Adenocarcinoma Patients

Simple Summary

The tumor microenvironment is a dynamic area, with continuous interaction between tumor cells and their surrounding environment. We aimed to investigate the relationship between tumor radiomic margin characteristics and prognosis in patients with lung cancer. When compared to the model with clinical variables only (C-index = 0.738), the model incorporating clinical variables and radiomic margin characteristics (C-index = 0.753) demonstrated a higher C-index for predicting overall survival. In the model integrating both clinical variables and radiomic margin characteristics, convexity, Laplace of Gaussian (LoG) kurtosis 3, and roundness factor were independent predictive factors of overall survival. Our study showed that radiomic margin characteristics helped predict overall survival in patients with lung adenocarcinomas, thus implying that the tumor margin contains prognostic information.

Abstract

We aimed to investigate the relationship between tumor radiomic margin characteristics and prognosis in patients with lung cancer. We enrolled 334 patients who underwent complete resection for lung adenocarcinoma. A quantitative computed tomography analysis was performed, and 76 radiomic margin characteristics were extracted. The radiomic margin characteristics were correlated with overall survival. The selected clinical variables and radiomic margin characteristics were used to calculate a prognostic model with subsequent internal and external validation. Nearly all of the radiomic margin characteristics showed excellent reproducibility. The least absolute shrinkage and selection operator (LASSO) method was used to select eight radiomic margin characteristics. When compared to the model with clinical variables only (C-index = 0.738), the model incorporating clinical variables and radiomic margin characteristics (C-index = 0.753) demonstrated a higher C-index for predicting overall survival. In the model integrating both clinical variables and radiomic margin characteristics, convexity, a Laplace of Gaussian (LoG) kurtosis of 3, and the roundness factor were each independently predictive of overall survival. In addition, radiomic margin characteristics were also correlated with the micropapillary subtype, and the sphericity value was able to predict the presence of the micropapillary subtype. In conclusion, our study showed that radiomic margin characteristics helped predict overall survival in patients with lung adenocarcinomas, thus implying that the tumor margin contains prognostic information.

Optimised architecture-based grading system as an independent prognostic factor in resected lung adenocarcinoma

AIMS

Considering morphological heterogeneity of lung adenocarcinoma (LUAD) and no objective prognostic grading system existing currently, we aim to establish an 'optimised architecture-based grading system' (OAGS) to predict prognosis for resected LUAD.

METHODS

A multicentral study involving three independent cohorts of LUAD was conducted. Predictive ability of the OAGS for recurrence-free probability (RFP) and overall survival (OS) was assessed in training cohort (n=228) by the area under the receiver operating characteristic curve (AUC), Harrell's concordance index (C-index) and Kaplan-Meier survival analyses, which was validated in testing (n=135) and validation (n=226) cohorts.

RESULTS

The OAGS consists of: grade 1 for lepidic, papillary or acinar predominant tumour with no or less than 5% of high-grade patterns (cribriform, solid and or micropapillary), grade 2 for lepidic, papillary or acinar predominant tumour with 5% or more of high-grade patterns, and grade 3 for cribriform, solid or micropapillary predominant tumour. In all stages, the OAGS outperformed the pattern-dominant grading system and IASLC grading system for predicting RFP (C-index, 0.649; AUC, 0.742) and OS (C-index, 0.685; AUC, 0.754). Multivariate analysis identified it as an independent predictor of both (RFP, p<0.001; OS, p<0.001). Furthermore, in pT1-2aN0M0 subgroup, the OAGS maintained its ability to predict recurrence (C-index, 0.699; AUC, 0.769) and stratified patients into different risk groups of RFP (p<0.001). These results were confirmed in testing and validation cohorts.

CONCLUSIONS

The OAGS is an independent prognostic factor and shows a robust ability to predict prognosis for resected LUAD.

Spread through air spaces (STAS) in invasive mucinous adenocarcinoma of the lung: Incidence, prognostic impact, and prediction based on clinicoradiologic factors

Background

Spread through air spaces (STAS) has recently been demonstrated to exhibit a negative impact on lung adenocarcinoma prognosis. However, most of these studies investigated STAS in nonmucinous adenocarcinoma. Here, we investigated the incidence of STAS in invasive mucinous adenocarcinoma (IMA) of the lung and evaluated whether tumor STAS was a risk factor of disease recurrence in IMA. We also examined clinicoradiologic factors in patients with IMA harboring STAS.

Methods

We reviewed pathologic specimens and imaging characteristics of primary tumors from 132 consecutive patients who underwent surgical resection for IMA to evaluate STAS. Patients with and without STAS were compared with respect to clinical characteristics as well as computed tomography (CT) imaging using logistic regression. The relationships between all variables including STAS and survival were analyzed.

Results

Among a total of 132 patients, full pathologic specimens were available for 119 patients, and STAS was observed in 86 (72.3%). IMA patients with STAS were significantly associated with older age, presence of lobulated and spiculated margins on CT scan (P = 0.009, P = 0.006, and P = 0.027). In multivariate analysis for overall survival (OS), STAS was a borderline independent poor prognostic predictor (P = 0.028). Older age, history of smoking, higher T stage, presence of lymph node metastasis, and consolidative morphologic type remained independent predictors for OS.

Conclusions

STAS was associated with reduced OS and was a borderline independent poor prognostic factor in IMA. IMA with STAS was associated with older age and presence of lobulated and spiculated margins on CT scan.

Key points

Significant findings of the study

Compared with other subtypes, IMA shows a higher incidence of STAS, which is an independent poor prognostic predictor even in IMA. Lobulated and spiculated margins on CT are associated with STAS.

What this study adds

Considering that STAS can carry the potential for aerogenous metastasis, predicting STAS using preoperative surrogate CT imaging is desirable to avoid limited resection.

Solid Nodule Appearance as a Predictor of Tumor Spread Through Air Spaces in Patients with Lung Adenocarcinoma: A Propensity Score Matching Study

OBJECTIVE

Spread through air spaces (STAS) has been reported to be an invasive histological pattern with poor prognosis in lung cancer; however, little is known about its intrinsic risk factors. This work analyzed the correlation between pathological and radiological features and STAS in resected lung adenocarcinomas.

PATIENTS AND METHODS

We retrospectively reviewed 1821 consecutive surgically treated patients with histologically diagnosed lung adenocarcinoma (174 positive for STAS and 1647 negative for STAS) from December 2017 to November 2018 at our institution. Propensity score matching identified 170 well-balanced pairs of patients. The correlations between pathological and radiological features and the presence of STAS were analyzed.

RESULTS

Before propensity matching, the incidence rate of STAS was 9.6% in all patients. In matched cohorts, multivariate analysis showed that the presence of STAS was significantly correlated with pure solid nodules (SNs) (p = 0.001) and solid/micropapillary patterns (SMPs) (p = 0.002). The odds ratio for STAS in SN-positive and SMP-positive adenocarcinoma against that in SN-negative and SMP-negative adenocarcinoma was 10.922 (95% confidence interval, 5.826-20.475; p < 0.001). Tumor differentiation, visceral pleural invasion (VPI), lymphovascular invasion (LVI), invasive adenocarcinoma, and non-lepidic subtype were significantly associated with STAS in the univariate analysis (p < 0.05); however, the differences failed to reach a significant level in the multivariate analysis.

CONCLUSION

We found that STAS was significantly correlated with several invasive clinicopathological patterns. The presence of SNs and SMPs were revealed as independent predictors for STAS, which could offer clinicians clues to identify STAS-positive adenocarcinoma.

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 Grading System for Invasive Pulmonary Adenocarcinoma: A Proposal From the International Association for the Study of Lung Cancer Pathology Committee

INTRODUCTION

A grading system for pulmonary adenocarcinoma has not been established. The International Association for the Study of Lung Cancer pathology panel evaluated a set of histologic criteria associated with prognosis aimed at establishing a grading system for invasive pulmonary adenocarcinoma.

METHODS

A multi-institutional study involving multiple cohorts of invasive pulmonary adenocarcinomas was conducted. A cohort of 284 stage I pulmonary adenocarcinomas was used as a training set to identify histologic features associated with patient outcomes (recurrence-free survival [RFS] and overall survival [OS]). Receiver operating characteristic curve analysis was used to select the best model, which was validated (n = 212) and tested (n = 300, including stage I-III) in independent cohorts. Reproducibility of the model was assessed using kappa statistics.

RESULTS

The best model (area under the receiver operating characteristic curve [AUC] = 0.749 for RFS and 0.787 for OS) was composed of a combination of predominant plus high-grade histologic pattern with a cutoff of 20% for the latter. The model consists of the following: grade 1, lepidic predominant tumor; grade 2, acinar or papillary predominant tumor, both with no or less than 20% of high-grade patterns; and grade 3, any tumor with 20% or more of high-grade patterns (solid, micropapillary, or complex gland). Similar results were seen in the validation (AUC = 0.732 for RFS and 0.787 for OS) and test cohorts (AUC = 0.690 for RFS and 0.743 for OS), confirming the predictive value of the model. Interobserver reproducibility revealed good agreement (k = 0.617).

CONCLUSIONS

A grading system based on the predominant and high-grade patterns is practical and prognostic for invasive pulmonary adenocarcinoma.

CT-Guided Core Biopsy for Peripheral Sub-solid Pulmonary Nodules to Predict Predominant Histological and Aggressive Subtypes of Lung Adenocarcinoma

BACKGROUND

Adenocarcinoma is the most common type of lung cancer, and pre-operative biopsy plays an important role to determine its major subtypes. As proposed by the International Association for the Study of Lung Cancer (IASLC), American Thoracic Society (ATS), and European Respiratory Society (ERS) in 2011, the predominant histological subtype of adenocarcinoma is an indicator of outcomes and recurrence rate. However, the value of CT-guided core biopsy in predicting the predominant subtype and detecting the presence of an aggressive subtype of adenocarcinoma, peripheral sub-solid nodule, has less been discussed.

METHODS

We retrospectively reviewed 318 consecutive peripheral sub-solid nodules that underwent percutaneous CT-guided lung biopsy and surgical resection, between October 2015 and December 2018 and were diagnosed as adenocarcinoma with histological subtype. The subtyping results from biopsy and surgical pathology were compared to evaluate the concordance rate.

RESULTS

The overall concordance rate between biopsy and surgical pathology in determining the predominant histological subtype was 64%. Better concordance was found in small tumors (≤ 2 cm), in predicting either predominant histology (χ² = 7.091, P = 0.008) or high grade adenocarcinoma, micropapillary and/or solid subtype, MIP-SOL (χ² = 22.301, P < 0.001). The analysis of ground glass opacity (GGO) component (C/T ratio) obtained significantly higher accuracy in the pure GGO group than in the other two groups in predicting predominant histology or high grade adenocarcinoma (χ² = 17.560, P < 0.001 and χ² = 61.938, P < 0.001, respectively).

CONCLUSIONS

CT-guided core biopsies provide additional value in predicting the histological subtype of lung adenocarcinoma after surgical resection, especially in small tumors (≤ 2 cm) or an initially pure GGO group.

Spread through air spaces affects survival and recurrence of patients with clinical stage IA non-small cell lung cancer after wedge resection

Background

Spread through air spaces (STAS) is reportedly a significant risk factor for recurrence and a prognostic factor in patients with non-small cell lung cancer (NSCLC), especially after sublobar resection. Because wedge resection (WR) is associated with insufficient margins, we hypothesized that STAS has a greater prognostic impact in patients who undergo WR compared with segmentectomy. We aimed to clarify the value of STAS as a prognostic factor in patients with NSCLC after WR.

Methods

We evaluated 217 patients with clinical stage IA NSCLC who underwent sublobar resection. The prognostic impact of STAS in these patients was compared between the WR (n=100) and segmentectomy (n=117) cases.

Results

STAS was present in 15.7% of the 217 patients. STAS was a significant prognostic factor for overall survival in univariate (P<0.001) and multivariate (P=0.003) analyses for the WR cases, but not the segmentectomy cases (P=0.399). STAS was also a significant prognostic factor for freedom from recurrence in univariate (P=0.010) and multivariate (P=0.024) analyses for the WR cases, but was only marginally significant for the segmentectomy cases (P=0.050, univariate analysis). The solid tumor size on chest computed tomography was significantly related to STAS. A cut-off solid tumor size of 1.7 cm for predicting the presence of STAS was determined by receiver operating characteristic analysis.

Conclusions

STAS was a significant prognostic factor for patients with clinical stage IA NSCLC who underwent WR, but not those who underwent segmentectomy.

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.

Three-Dimensional Histologic, Immunohistochemical, and Multiplex Immunofluorescence Analyses of Dynamic Vessel Co-Option of Spread Through Air Spaces in Lung Adenocarcinoma

INTRODUCTION

Spread through air spaces (STAS) is a method of invasion in lung adenocarcinoma and is associated with tumor recurrence and poor survival. The spatial orientation of STAS cells in the lung alveolar parenchyma is not known. The aim of this study was to use high-resolution and high-quality three-dimensional (3D) reconstruction of images from immunohistochemical (IHC) and multiplex immunofluorescence (IF) experiments to understand the spatial architecture of tumor cell clusters by STAS in the lung parenchyma.

METHODS

Four lung adenocarcinomas, three micropapillary-predominant and one solid predominant adenocarcinoma subtypes, were investigated. A 3D reconstruction image was created from formalin-fixed, paraffin-embedded blocks. A total of 350 serial sections were obtained and subjected to hematoxylin and eosin (100 slides), IHC (200 slides), and multiplex IF staining (50 slides) with the following antibodies: cluster of differentiation 31, collagen type IV, thyroid transcription factor-1, and E-cadherin. Whole slide images were reconstructed into 3D images for evaluation.

RESULTS

Serial 3D image analysis by hematoxylin and eosin, IHC, and IF staining revealed that the micropapillary clusters and solid nests of STAS are focally attached to the alveolar walls, away from the main tumor.

CONCLUSIONS

Our 3D reconstructions found that STAS tumor cells can attach to the alveolar walls rather than appearing free floating, as seen on the two-dimensional sections. This suggests that the tumor cells detach from the main tumor, migrate through air spaces, and reattach to the alveolar walls through vessel co-option, allowing them to survive and grow. This may explain the higher recurrence rate and worse survival of patients with STAS-positive tumors who undergo limited resection than those who undergo lobectomy.

Tumor Spread Through Air Spaces Is a Predictor of Occult Lymph Node Metastasis in Clinical Stage IA Lung Adenocarcinoma

INTRODUCTION

In patients with stage IA lung adenocarcinoma (ADC), sublobar resection and tumor spread through air spaces (STAS) are associated with high rates of locoregional recurrence, half of which occur within the regional lymph nodes (LNs). Our objectives were to investigate the association between occult LN metastasis (ONM) and STAS and to assess their prognostic value in patients with clinical stage IA lung ADC.

METHODS

The association between STAS and ONM was analyzed in patients who underwent lobectomy and LN dissection for clinical stage IA lung ADC (n = 809). Multivariable logistic regression analysis was carried out to identify predictors of ONM. Site-specific recurrence by surgical procedure was investigated in patients with pathologic node-negative disease (n = 1055) using a competing risk approach.

RESULTS

ONM was identified in 129 patients (16%)-one-third of ONMs were located only in intrapulmonary nodes. STAS was more common in patients with ONM than in those without ONM (67% versus 39%; p < 0.001) and in patients with multiple ONMs than in those with a single ONM (86%-89% versus 60%-67%). STAS was a significant predictor of ONM (p = 0.004) on multivariable analysis, independent of tumor size, maximum standardized uptake value, and lymphovascular invasion. In patients with STAS-positive ADC (high ONM risk), the risk of recurrence in the treated lobe and regional LNs increased as the extent of resection decreased (recurrence risk: lobectomy < segmentectomy < wedge resection). In patients with STAS-negative ADC, the risk of locoregional recurrence did not differ by procedure type.

CONCLUSIONS

Presence of STAS predicts ONM in patients with clinical stage IA lung ADC and can help stratify risk of recurrence by extent and type of resection.

Lung Cancer Pathology: Current Concepts

Lung cancer can be diagnosed based on histologic biopsy or cytologic specimens. The 2015 World Health Organization Classification of Lung Tumors addressed the diagnosis of lung cancer in resection specimens and in small biopsies and cytology specimens. For these small specimens, diagnostic terms and criteria are recommended. Targetable mutations such as EGFR and ALK rearrangements emphasize the importance of managing these small specimens for molecular testing.

Expansion of the Concept of Micropapillary Adenocarcinoma to Include a Newly Recognized Filigree Pattern as Well as the Classical Pattern Based on 1468 Stage I Lung Adenocarcinomas

INTRODUCTION

The classical micropapillary (MIP) pattern is defined in the 2015 WHO classification as tumor cells growing in papillary tufts forming florets that lack fibrovascular cores, and it is associated with poor prognosis. We observed a novel pattern that we termed a filigree MIP pattern and investigated its relationship with the classical MIP pattern.

METHODS

Filigree pattern was defined as tumor cells growing in delicate, lace-like, narrow stacks of cells without fibrovascular cores. We required at least three piled-up nuclei from the alveolar wall basal layer, with a breadth of up to three cells across. To assess the relationship of the filigree pattern with the classical MIP pattern, we documented their frequencies in the context of the clinical and pathologic characteristics of 1468 stage I invasive adenocarcinomas, including survival analysis using cumulative incidence of recurrence by competing risks.

RESULTS

We observed the filigree MIP pattern in 35% of cases. By including the filigree pattern as an MIP pattern, we identified 57 more MIP predominant cases in addition to the previously diagnosed 87 MIP predominant adenocarcinomas. These 57 cases were reclassified from papillary (n = 37), acinar (n = 16), and solid (n = 4) predominant adenocarcinoma, respectively. Of the 144 MIP predominant adenocarcinomas, the filigree predominant MIP pattern (n = 78) showed a poor prognosis like the classical predominant MIP pattern (n = 66) (p = 0.464). In addition, like the classical MIP pattern (p = 0.010), even a small amount (≥5%) of filigree MIP pattern was significantly associated with worse cumulative incidence of recurrence (p = 0.001) in multivariable analysis.

CONCLUSION

The frequent association with the classical MIP pattern and the similar poor prognosis supports inclusion of the filigree pattern in the MIP pattern subtype.

Spread Through Air Spaces (STAS) Is Prognostic in Atypical Carcinoid, Large Cell Neuroendocrine Carcinoma, and Small Cell Carcinoma of the Lung

INTRODUCTION

Tumor spread through air spaces (STAS) has prognostic significance in lung adenocarcinoma and squamous cell carcinoma. We sought to investigate the prognostic importance of STAS in lung neuroendocrine tumors (NETs).

METHODS

All tumor slides from patients with resected pathologic stage I to III lung NETs (N = 487) (299 with typical carcinoid [TC], 38 with atypical carcinoid [AC], 93 with large cell neuroendocrine carcinoma [LCNEC], and 57 with SCLC) treated between 1992 and 2012 were evaluated for presence of STAS. Cumulative incidence of recurrence (CIR) and lung cancer-specific cumulative incidence of death (LC-CID) were analyzed by using a competing-risks approach.

RESULTS

STAS was identified in 26% of NETs (16% of TCs, 37% of ACs, 43% of LCNECs, and 46% of SCLCs). STAS was associated with distant metastasis, as well as with higher CIR and LC-CID in the overall cohort and in the AC, LCNEC, and SCLC cohorts (owing to a small number of recurrences and deaths [<5], prognostic analysis was not performed in the TC cohort). In multivariable analysis stratified by stage, STAS was significantly associated with higher CIR (subhazard ratio = 2.85, 95% confidence interval: 1.73-4.68, p < 0.001) and LC-CID (subhazard ratio = 2.72, 95% confidence interval: 1.57-4.70, p < 0.001), independent of histologic subtype. STAS was independently associated with CIR and LC-CID in the LCNEC cohort and LC-CID in the SCLC cohort.

CONCLUSIONS

In patients with lung NETs, STAS is associated with early distant metastasis and worse LC-CID. In patients with LCNEC or SCLC, STAS is an independent poor prognostic factor.

Challenges for real-time intraoperative diagnosis of high risk histology in lung adenocarcinoma: A necessity for sublobar resection

Recently, the incidence of small, peripheral lung adenocarcinoma has been increasing as lung cancer screening with radiologic examination is more widely performed. Tumor size is one of the determinants of the prognostic outcome in clinically node-negative lung adenocarcinoma. Sublobar resection has been proposed as one of the minimally invasive surgical options for small-sized adenocarcinomas. Despite the lack of robust clinical trial evidence, sublobar resection has become more popular, especially in developed countries where less extensive surgery may be of benefit in a population where the age of the elderly is growing. However, high risk histologic features such as micropapillary subtype and tumor spread through air space (STAS) have been associated with a significantly higher risk of local recurrence after sublobar resection, but not after lobectomy. Surgical decision-making based on frozen section diagnosis of high risk histologic features may be useful to prevent local control failure after sublobar resection. At the present time, there is little evidence to demonstrate the diagnostic accuracy of identifying high risk histologic features on frozen section. One study has so far demonstrated that diagnostic accuracy of identifying STAS is higher than that of identifying the micropapillary subtype. Additionally, the presence of STAS has been found to be more strongly associated with local recurrence in patients who had undergone sublobar resection. Although further investigation is required for validation of this finding, STAS diagnosis on frozen section may shed further light on intraoperative surgical decision-making during sublobar resection. To this end, we review the recently published data on the intraoperative identification of high risk features.