ES 01.02 New Histological Classification

Objective: The present study is to investigate the expression of CD34, β-Tubulin-III and Collagen IV-Laminin in adenocarcinoma in situ (AIS), the AIS component of minimally invasive adenocarcinoma (MIA), and early invasive foci, in order to find a valuable immunohistochemical marker for discriminating AIS and its early invasive foci. Methods: A total of 51 AIS patients and 88 MIA patients were included in the present study. In addition, 40 atypical adenomatous hyperplasia (AAH) patients and 54 invasive adenocarcinoma (IA) patients were included as control. Immunohisto-chemical staining of β-Tubulin-III, CD34, CD31, F8 and Collagen IV-Laminin was performed by serial sectioning. β-Tubulin-III was used to show invasive adenocarcinoma foci, CD34 was used to indicate interstitial cells in AIS, CD31 and F8 were used to identify capillary endothelial cells in tumor tissues, and Collagen IV-Laminin was used to visualize the basement membrane component of AIS. Results: The basement membranes and interstitial cells of AAH, AIS and the AIS component of MIA had positive expression of CD34, while mucinous AIS and various invasive adenocarcinomas had no CD34-positive basement membranes or interstitial cells. Invasive cancers such as alveolar adenocarcinoma, papillary adenocarcinoma, micropapillary adenocarcinoma and solid adenocarcinoma had strong positive expression of β-Tubulin-III, while AAH, AIS and the AIS component of MIA, and invasive mucinous adenocarcinoma had negative expression of β-Tubulin-III. AAH, AIS and the AIS component of MIA were surrounded by basement membranes with positive expression of Collagen IV-Laminin, AIS and the AIS component of MIA had significantly thickened basement membranes, and none of invasive adenocarcinomas was surrounded by basement membranes. Conclusions: The present study demonstrates that immunohistochemical staining of CD34, β-Tubulin-III, and Collagen IV-Laminin discriminates AIS component of lung adenocarcinoma from early invasive foci, with the efficacy of β-Tubulin-III being the best. Staining of β-Tubulin-III precisely identifies the early invasive foci of MIA, and can be used as a marker for the identification of the early invasive foci of nonmucinous lung adenocarcinoma.

Pulmonary adenocarcinoma (ADC) is a very diverse disease, both genetically and histologically, which displays extensive intratumor heterogeneity with numerous acquired mutations. ADC is the most common type of lung cancer and is believed to arise from adenocarcinoma in situ (AIS) which then progresses to minimally invasive adenocarcinoma (MIA). In patients of European ethnicity, we analyzed genetic mutations in AIS (n = 10) and MIA (n = 18) and compared the number of genetic mutations with advanced ADC (n = 2419). Using next-generation sequencing, the number of different mutations detected in both AIS (87.5%) and MIA (94.5%) were higher (p < 0.001) than in advanced ADC (53.7%). In contrast to the high number of mutations in Kirsten rat sarcoma virus gene (KRAS) in advanced ADC (34.6%), there was only one case of AIS with KRAS G12C mutation (3.5%; p < 0.001) and no cases of MIA with KRAS mutation (p < 0.001). In contrast to the modest prevalence of epidermal growth factor receptor (EGFR) mutations in advanced ADC (15.0%), the fraction of EGFR mutant cases was higher in both in AIS (22.2%) and MIA (59.5%; p < 0.001). The EGFR exon 19 deletion mutation was more common in both MIA (50%; n = 6/12) and ADC (41%; n = 149/363), whereas p.L858R was more prevalent in AIS (75%; n = 3/4). In contrast to pulmonary advanced ADC, KRAS driver mutations are less common, whereas mutations in EGFR are more common, in detectable AIS and MIA.

Microenvironmental changes in the progression from adenocarcinoma in situ to minimally invasive adenocarcinoma and invasive lepidic predominant adenocarcinoma of the lung

BackgroundAccording to the WHO classification for lung cancer, adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) have a better prognosis than invasive adenocarcinoma (IAD). However, detecting the foci of invasion in lung adenocarcinomas radiologically remains difficult. The present study examined whether or not differences in the cytological characteristics between IAD and AIS or MIA (noninvasive or minimally invasive adenocarcinomas [NMIAD]) plays a role in the differential diagnosis.MethodsSeventy surgical resection specimens of primary lung adenocarcinoma with preoperative cytology, in which several parameters were evaluated and assessed.ResultsThe histopathological diagnoses of surgical resection specimens were AIS in 8, MIA in 31, IAD in 31 including lepidic adenocarcinoma in 9, and papillary adenocarcinoma in 22. NMIAD had a 100% 5‐year recurrence‐free survival (RFS), while IAD had an 82.8% 5‐year RFS. The numbers of tumor cells (at ×10 magnification in 10 fields) were 60.3 ± 40.5 in IAD and 39.8 ± 28.7 in NMIAD (P = 0.0017). A univariate analysis of cytological parameters revealed significant differences in large tumor cell clusters, three‐dimensional (3D) tumor cell clusters, and irregular nuclear contours between the two groups. The frequency of irregular nuclear contours continued to be significantly different according to a multivariate analysis.ConclusionLarge or 3D tumor cell clusters and irregular nuclear contours may be important cytological factors for distinguishing IAD from NMIAD, with the latter being potentially more important for distinguishing between the two groups.

Stepwise progression from adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) to lepidic predominant adenocarcinoma (LPA) was proposed by various scholars. Interstitial tumor-associated macrophages (TAMs) and various potential chemokines involved in the progression from AIS/MIA to LPA were hypothesized. In the present study, immunohistochemistry or immunofluorescent double staining was used to detect the expression of the TAMs marker cluster of differentiation (CD) 68, tumor-derived colony-stimulating factor (CSF)-1, interleukin (IL)-6, matrix metalloproteinase (MMP)-2, E-cadherin and Snail in lung adenocarcinoma specimens, including AIS/MIA, LPA and other types. It was observed that infiltrating TAMs were negatively associated with the prognosis of patients, and that the infiltration degree of interstitial TAMs was higher in LPA than that in AIS/MIA. In addition, E-cadherin, Snail and MMP-2 expression were significantly correlated with the infiltration degree of TAMs. Survival analysis revealed that co-expression of CD68, CSF-1 and IL-6 was an independent prognostic factor. Stratified analysis demonstrated that, in AIS/MIA patients, there was a statistically significant difference between the number of TAMs (TAMs ≤25 and TAMs >25) in the CD68+CSF-1+IL-6+ group compared with other groups (including CD68+CSF-1-IL-6-, CD68+CSF-1+IL-6-, CD68+CSF-1-IL-6+ and CD68- groups). By contrast, in patients with TAMs >25 and in patients with positive CD68, CSF-1 and IL-6 expression, the survival rates were not significantly different between AIS/MIA and LPA. These results suggested that co-expression of TAMs marker CD68, CSF-1 and IL-6 may be a valuable independent prognostic predictor in lung adenocarcinoma. TAMs may facilitate AIS/MIA progression to LPA, which may be closely associated with the induction of the epithelial-mesenchymal transition.

Purpose: This study aimed to investigate the potential of computed tomography (CT) imaging features and texture analysis to distinguish bronchiolar adenoma (BA) from adenocarcinoma in situ (AIS)/minimally invasive adenocarcinoma (MIA).Materials and Methods: Fifteen patients with BA, 38 patients with AIS, and 36 patients with MIA were included in this study. Clinical data and CT imaging features of the three lesions were evaluated. Texture features were extracted from the thin-section unenhanced CT images using Artificial Intelligence Kit software. Then, multivariate logistic regression analysis based on selected texture features was employed to distinguish BA from AIS/MIA. Receiver operating characteristics curves were performed to determine the diagnostic performance of the features.Results: By comparison with AIS/MIA, significantly different CT imaging features of BA included nodule type, tumor size, and pseudo-cavitation sign. Among them, pseudo-cavitation sign had a moderate diagnostic value for distinguishing BA and AIS/MIA (AUC: 0.741 and 0.708, respectively). Further, a total of 396 quantitative texture features were extracted. After comparation, the top six texture features showing the most significant difference between BA and AIS or MIA were chosen. The ROC results showed that these key texture features had a high diagnostic value for differentiating BA from AIS or MIA, among which the value of a comprehensive model with six selected texture features was the highest (AUC: 0.977 or 0.976, respectively) for BA and AIS or MIA. These results indicated that texture analyses can effectively improve the efficacy of thin-section unenhanced CT for discriminating BA from AIS/MIA.Conclusion: CT texture analysis can effectively improve the efficacy of thin-section unenhanced CT for discriminating BA from AIS/MIA, which has a potential clinical value and helps pathologist and clinicians to make diagnostic and therapeutic strategies.

Early Stage Non–Small-Cell Lung Cancer: Surgical Implications of the New Adenocarcinoma Classification

Introduction: The widespread of implementation of computed tomography (CT) has resulted in a drastic increase in the detection of small pulmonary nodules presenting as ground glass opacities (GGOs). Many of these GGOs are atypical adenomatous hyperplasia (AAH), adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and sometimes invasive adenocarcinoma (IAC). The concept of a continuum between the precursor lesions AAH and AIS to MIA and frankly invasive IAC is backed by a wealth of recent data showing a gradual decrease in overall survival from 100% for AAH, AIS and MIA to moderately lower rates for IAC. A growing body of evidence suggests that the immune response is a significant determinant of cancer progression. However, little is known about the immune microenvironment features in the early stages of lung carcinogenesis. Methods: A total of 40 tumor tissue samples including 10 AAH, 10 AIS, 10 MIA and 10 early IAC from 40 patients who underwent surgical resection of pulmonary nodules at Yancheng No.1 People's Hospital, China were included. Immunohistochemistry (IHC) staining for the expression of CD3, CD4, CD8 and programmed death ligand 1 (PD-L1) to assess the role of T-cell immune surveillance in these pre- and early lung cancers were performed. Results: We observed CD3, CD4, CD8 and PD-L1 positivity in AAH, AIS, MIA and IAC, suggesting that immunoediting has started before the invasion. Higher expressions of CD3, CD4, CD8 and PD-L1 in IAC implying tumor invasion. Conclusions: Our preliminary results of the immune subgroups provide evidence for immune recognition in pulmonary premalignancy and are critical for understanding tumorigenesis and the development of effective preventive and interception strategies. Associations with genomic landscape is underway. Citation Format: Liting Guo, Weiwei Shao. Immune microenvironment features of lung adenomatous premalignancy in a Chinese cohort [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1002.

This review gives a comprehensive overview on recent developments in the classification of neoplastic lung lesions with lepidic growth patterns, comprising the adenocarcinoma (ADC) precursor lesions atypical adenomatous hyperplasia (AAH), adenocarcinoma in situ (AIS), and minimally invasive adenocarcinoma (MIA) as well as lepidic predominant adenocarcinoma (LPA). The concept of a continuum between the precursor lesions AAH and AIS to MIA and frankly invasive ADC is backed by a wealth of recent data showing a gradual decrease in overall survival from 100% for AAH, AIS, and MIA to moderately lower rates for LPA. Further, it has been shown that the morphologic categorization of these tumors can be done with reasonable reliability and that nonmucinous lepidic tumors show distinct molecular alterations with high rates of epidermal growth factor receptor mutations. Importantly, lepidic tumor growth is also mirrored by specific characteristics in computed tomography images, arguing for a combined assessment of histomorphology and imaging data for an optimized classification of lepidic neoplasms. The validity and clinical importance of the novel concept of ADC precursor lesions and LPA have been confirmed by clinical, radiological, morphological, and molecular data. Thereby, it has evolved into a valuable tool to aid in clinical decision-making.

Prognostic Patterns in the Histopathology of Pulmonary Adenocarcinoma

PurposeThe goal of current study was to introduce noninvasive and reproducible MRI methods for in vivo functional assessment of lung adenocarcinoma (LUAD).MethodsForty-four patients with pathologically confirmed LUAD were included in this study. All the lesions were classified as adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), or invasive adenocarcinoma (IA). The IA lesions were further divided into five subtype patterns, including acinar, lepidic, papillary, micropapillary and solid. Tumors were grouped depending on predominant subtype: low grade (AIS, MIA or lepidic predominant), intermediate grade (papillary or acinar predominant) and high grade (micropapillary, or solid predominant). Spirometry was performed according to American Thoracic Society guidelines. For each patient, Intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI) analysis and oxygen-enhanced MRI (OE-MRI) analysis were performed. Spearman’s test was used to assess the relationship between a) whole lung mean percent signal enhancement (PSE) and pulmonary function tests (PFTs) parameters; b) IVIM-derived parameters and PFTs parameters; c) tumor mean PSE and IVIM-derived parameters. Kruskal -Wallis tests were applied to test the difference of tumor mean PSE and IVIM-derived parameters between different histological tumor grades. Receiver operating characteristics (ROC) analysis was used to evaluate the diagnostic performance.ResultsWhole lung mean PSE was significantly positively correlated with PFTs parameters (r = 0.40 ~ 0.44, P < 0.05). f value derived from IVIM-DWI was significantly negatively correlated with PFTs parameters (r = -0.38 ~ -0.47, P < 0.05). Both tumor mean PSE (P = 0.030 < 0.05) and f (P = 0.022 < 0.05) could differentiate different histological grades. f was negatively correlated with tumor mean PSE (r = -0.61, P < 0.001). For the diagnostic performance, the combination of tumor mean PSE and f outperformed than using tumor mean PSE or f alone in both sensitivity and area under the ROC curve.ConclusionsThe combined measurement of OE-MRI and IVIM-DWI may serve as a promising method for the noninvasive and non-radiation evaluation of pulmonary function. Quantitative analyses achieved by OE-MRI and IVIM-DWI offer an approach of the classification of LUAD subtypes.

This study investigated the accuracy of intraoperative frozen section (FS) diagnosis for predicting the final pathology (FP) of peripheral small-sized lung adenocarcinoma and evaluated its usefulness in sublobar resection. The records of 803 patients with clinical stage I peripheral lung adenocarcinoma who underwent sublobar resection for FS diagnosis to guide surgical strategy were reviewed. The surgical extension was mainly based on FS. The FS were stratified into atypical adenomatous hyperplasia, adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and invasive adenocarcinoma. The diagnostic accuracy of FS, the reasons for the discrepancy between FS and FP, and the clinical influence of the FS errors were evaluated. To assess the survival of patients with different subtypes after surgery, 301 patients were identified for prognosis evaluation. The total concordance rate between FS and FP was 84.4%. When atypical adenomatous hyperplasia, AIS, and MIA were classified together as a low-risk group, the concordance rate was 95.9%. Most discrepant cases were the underestimation of AIS and MIA. The diagnostic accuracy of FS for tumors ≤ 1 cm and larger than 1 cm in diameter was 79.6% and 90.8%, respectively (P < .01). The FS errors had significant clinical impact on 0.9% of the 803 patients due to insufficient resection. The 5-year recurrence-free survival rate (100%) was significantly better for the patients with AIS/MIA than for patients with invasive adenocarcinoma (74.1%, P < .01). Frozen pathology has a high concordance rate with FP. Precise diagnosis by intraoperative FS is an effective method to guide resection strategy for peripheral small-sized lung adenocarcinoma.

MS 03.03 Limited vs. Standard Surgical Resection: European Experience

This study aims to develop a CT-based radiomic features analysis approach for diagnosis of ground-glass opacity (GGO) pulmonary nodules, and also assess whether computer-aided diagnosis (CADx) performance changes in classifying between benign and malignant nodules associated with histopathological subtypes namely, adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and invasive adenocarcinoma (IAC), respectively.The study involves 182 histopathology-confirmed GGO nodules collected from two cancer centers. Among them, 59 are benign, 50 are AIS, 32 are MIA, and 41 are IAC nodules. Four training/testing data sets—(1) all nodules, (2) benign and AIS nodules, (3) benign and MIA nodules, (4) benign and IAC nodules—are assembled based on their histopathological subtypes. We first segment pulmonary nodules depicted in CT images by using a 3D region growing and geodesic active contour level set algorithm. Then, we computed and extracted 1117 quantitative imaging features based on the 3D segmented nodules. After conducting radiomic features normalization process, we apply a leave-one-out cross-validation (LOOCV) method to build models by embedding with a Relief feature selection, synthetic minority oversampling technique (SMOTE) and three machine-learning classifiers namely, support vector machine classifier, logistic regression classifier and Gaussian Naïve Bayes classifier.When separately using four data sets to train and test three classifiers, the average areas under receiver operating characteristic curves (AUC) are 0.75, 0.55, 0.77 and 0.93, respectively. When testing on an independent data set, our scheme yields higher accuracy than two radiologists (61.3% versus radiologist 1: 53.1% and radiologist 2: 56.3%).This study demonstrates that: (1) the feasibility of using CT-based radiomic features analysis approach to distinguish between benign and malignant GGO nodules, (2) higher performance of CADx scheme in diagnosing GGO nodules comparing with radiologist, and (3) a consistently positive trend between classification performance and invasive grade of GGO nodules. Thus, to improve the CADx performance in diagnosing of GGO nodules, one should assemble an optimal training data set dominated with more nodules associated with non-invasive lung adenocarcinoma (i.e. AIS and MIA).

Objective To evaluate volume doubling time (VDT) and net mass doubling time of tumor (nMDT) of pulmonary pure ground glass nodules (PGGN) of different pathological types and to investigate whether VDT and nMDT can help to differentiate invasive pulmonary adenocarcinomas from minimally invasive adenocarcinomas and preinvasive lesions. Methods Fifty-one pathologically confirmed pGGNs in 46 patients were retrospectively evaluated, in whom at least two HRCT scans were obtained preoperatively (median scan times, 3 times; range, 2—6 times) with 1-month or longer follow-up interval(median follow-up interval, 251 days; range, 30-1 552 days). According to the rechecked results of the postoperative pathological section, 51 pGGNs were divided into two groups: group A, invasive adenocarcinoma (IAC), 30 pGGNs (58.8%); group B, 21 pGGNs (41.2%), including 8 minimally invasive adenocarcinoma (MIA), 7 adenocarcinomas in situ (AIS) and 6 atypical adenomatous hyperplasia (AAH). The volume, cumulative percentage of volume growth and VDTs of pGGNs were automatically acquired by Lung VCAR (advantage windows 4.6, GE HealthCare). Subsequently, the mass, cumulative percentage of mass growth and nMDTs of pGGNs were calculated. The count data and measurement data between two groups were compared using Fisher exact probability and Mann-Whitney U test, respectively. A pairwise comparision were performed by using Wilcoxon signed-rank test. Subsequently, the receiver operating characteristic (ROC) curve was used to determine the optimal cut-off values of VDT and nMDT for the differential diagnosis of IAC and MIA/AIS/AAH, and calculated the area under the curve (AUC). Results The median VDT and nMDT of 51 pGGNs were 1 854.11 days (range, 165.22—+∞ days) and 1 138.45 days (range, 95.92—+∞ days), respectively. The median nMDT was shorter than the median VDT, and the difference was significant (Z=-2.444, P=0.015). The median VDTs of IAC and MIA/AIS/AAH were 847.07 days (165.22—+∞ days) and 4 460.09 days (691.14—+∞ days), respectively. The median nMDTs of IAC, MIA/AIS/AAH were 769.93 days (95.92—+∞ days) and 3814.77 days (611.56—+∞ days), respectively. The median VDT and nMDT of IAC were significantly shorter than those of MIA/AIS/AAH (Z=-3.443,-3.860, P<0.01, respectively). Differentiating IAC from MIA/AIS/AAH, the optimal cutoff value of VDT was 2095.86 days (sensitivity, 71.4%; specificity, 80.0%), the optimal cutoff value of nMDT was 1 169.77 days (sensitivity, 81.0%; specificity, 76.7%). Conclusions In pulmonary pGGNs, IAC showed significantly shorter VDT and nMDT than MIA/AIS/AAH. When VDT is shorter than 2 095.86 days or nMDT is shorter than 1 169.77 days, IAC is suggested. Key words: Lung neoplasms; Tomography, X-ray computed; Ground glass nodule; Volume doubling time; Mass doubling time