Interobserver Variation among Pathologists and Refinement of Criteria in Distinguishing Separate Primary Tumors from Intrapulmonary Metastases in Lung

Multiple primary lung cancer: Updates and perspectives

Management of multiple primary lung cancer (MPLC) remains challenging, partly due to its increasing incidence, especially with the significant rise in cases of multiple lung nodules caused by low-dose computed tomography screening. Moreover, the indefinite pathogenesis, diagnostic criteria, and treatment selection add to the complexity. In recent years, there have been continuous efforts to dissect the molecular characteristics of MPLC and explore new diagnostic approaches as well as treatment modalities, which will be reviewed here, with a focus on newly emerging evidence and future perspectives, hope to provide new insights into the management of MPLC and serve as inspiration for future research related to MPLC.

Presence of focal usual interstitial pneumonia is a key prognostic factor in progressive pulmonary fibrosis

AIMS

Progressive pulmonary fibrosis (PPF) is a newly recognised clinical phenotype of interstitial lung diseases in the 2022 interstitial pulmonary fibrosis (IPF) guidelines. This category is based entirely on clinical and radiological factors, and the background histopathology is unknown. Our objective was to investigate the histopathological characteristics of PPF and to examine the correlation between usual interstitial pneumonia (UIP) and prognosis in this new disease type. We hypothesised that the presence of UIP-like fibrosis predicts patients' survival in PPF cases.

METHODS AND RESULTS

We selected 201 cases fulfilling the clinical criteria of PPF from case archives. Cases diagnosed as IPF by a multidisciplinary team were excluded. Whole slide images were evaluated by three pathologists who were blinded to clinical and radiological data. We measured areas of UIP-like fibrosis and calculated what percentage of the total lesion area they occupied. The presence of focal UIP-like fibrosis amounting to 10% or more of the lesion area was seen in 148 (73.6%), 168 (83.6%) and 165 (82.1%) cases for each pathologist, respectively. Agreement of the recognition of UIP-like fibrosis in PPF cases was above κ = 0.6 between all pairs. Survival analysis showed that the presence of focal UIP-like fibrosis correlated with worsened survival under all parameters tested (P < 0.001).

CONCLUSIONS

The presence of UIP-like fibrosis is a core pathological feature of clinical PPF, and its presence within diseased areas is associated with poorer prognosis. This study highlights the importance of considering the presence of focal UIP-like fibrosis in the evaluation and management of PPF.

Genomic Staging of Multifocal Lung Squamous Cell Carcinomas Is Independent of the Comprehensive Morphologic Assessment

INTRODUCTION

Morphologic and molecular data for staging of multifocal lung squamous cell carcinomas (LSCCs) are limited. In this study, whole exome sequencing (WES) was used as the gold standard to determine whether multifocal LSCC represented separate primary lung cancers (SPLCs) or intrapulmonary metastases (IPMs). Genomic profiles were compared with the comprehensive morphologic assessment.

METHODS

WES was performed on 20 tumor pairs of multifocal LSCC and matched normal lymph nodes using the Illumina NovaSeq6000 S4-Xp (Illumina, San Diego, CA). WES clonal and subclonal analysis data were compared with histologic assessment by 16 thoracic pathologists. In addition, the immune gene profiling of the study cases was characterized by the HTG EdgeSeq Precision Immuno-Oncology Panel.

RESULTS

By WES data, 11 cases were classified as SPLC and seven cases as IPM. Two cases were technically suboptimal. Analysis revealed marked genomic and immunogenic heterogeneity, but immune gene expression profiles highly correlated with mutation profiles. Tumors classified as IPM have a large number of shared mutations (ranging from 33.5% to 80.7%). The agreement between individual morphologic assessments for each case and WES was 58.3%. One case was unanimously interpreted morphologically as IPM and was in agreement with WES. In a further 17 cases, the number of pathologists whose morphologic interpretation was in agreement with WES ranged from two (one case) to 15 pathologists (one case) per case. Pathologists showed a fair interobserver agreement in the morphologic staging of multiple LSCCs, with an overall kappa of 0.232.

CONCLUSIONS

Staging of multifocal LSCC based on morphologic assessment is unreliable. Comprehensive genomic analyses should be adopted for the staging of multifocal LSCC.

[Recent Advances in Diagnosis and Treatment Strategies for Multiple Primary Lung Cancer]

As the utilization of computed tomography in lung cancer screening becomes more prevalent in the post-pandemic era, the incidence of multiple primary lung cancer (MPLC) has surged in various countries and regions. Despite the continued application of advanced histologic and sequencing technologies in this research field, the differentiation between MPLC and intrapulmonary metastasis (IM) remains challenging. In recent years, the specific mechanisms of genetic and environmental factors in MPLC have gradually come to light. Lobectomy still predominates in the treatment of MPLC, but the observation that tumor-specific sublobar resection has not detrimentally impacted survival appears to be a viable option. With the evolution of paradigms, the amalgamated treatment, primarily surgical, is an emerging trend. Among these, stereotactic ablative radiotherapy (SABR) and lung ablation techniques have emerged as efficacious treatments for early unresectable tumors and control of residual lesions. Furthermore, targeted therapies for driver-positive mutations and immunotherapy have demonstrated promising outcomes in the postoperative adjuvant phase. In this manuscript, we intend to provide an overview of the management of MPLC based on the latest discoveries.
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Towards the molecular era of discriminating multiple lung cancers

In the era of histopathology-based diagnosis, the discrimination between multiple lung cancers (MLCs) poses significant uncertainties and has thus become a clinical dilemma. However, recent significant advances and increased application of molecular technologies in clonal relatedness assessment have led to more precision in distinguishing between multiple primary lung cancers (MPLCs) and intrapulmonary metastasis (IPMs). This review summarizes recent advances in the molecular identification of MLCs and compares various methods based on somatic mutations, chromosome alterations, microRNAs, and tumor microenvironment markers. The paper also discusses current challenges at the forefront of genomics-based discrimination, including the selection of detection technology, application of next-generation sequencing, and intratumoral heterogeneity (ITH). In summary, this paper highlights an entrance into the primary stage of molecule-based diagnostics.

Genomic Profiling With Large-Scale Next-Generation Sequencing Panels Distinguishes Separate Primary Lung Adenocarcinomas From Intrapulmonary Metastases

The distinction between different separate primary lung cancers (SPLCs) and intrapulmonary metastases (IPMs) is a challenging but clinically significant issue. Histopathology-based classification is the current practice; however, it is subjective and affected by interobserver variability. Recently, next-generation sequencing (NGS) panels have been used in lung cancer diagnostics. This study aimed to investigate the value of large-scale NGS panels for distinguishing between SPLCs and IPMs. A total of 32 patients with 69 lung adenocarcinomas were included. Comprehensive histopathologic assessments of multiple pulmonary adenocarcinomas were performed independently by 3 pathologists. The consensus of histopathologic classification was determined by a majority vote. Genomic analysis was performed using an amplicon-based large-scale NGS panel, targeting single-nucleotide variants and short insertions and deletions in 409 genes. Tumor pairs were classified as SPLCs or IPMs according to a predefined molecular classification algorithm. Using NGS and our molecular classification algorithm, 97.6% of the tumor pairs can be unambiguously classified as SPLCs or IPMs. The molecular classification was predictive of postoperative clinical outcomes in terms of overall survival (P = .015) and recurrence-free interval (P = .0012). There was a moderate interobserver agreement regarding histopathologic classification (κ = 0.524 at the tumor pair level). The concordance between histopathologic and molecular classification was 100% in cases where pathologists reached a complete agreement but only 53.3% where they did not. This study showed that large-scale NGS panels are a powerful modality that can help distinguish SPLCs from IPMs in patients with multiple lung adenocarcinomas and objectively provide accurate risk stratification.

Reproducibility and Feasibility of Classification and National Guidelines for Histological Diagnosis of Canine Mammary Gland Tumours: A Multi-Institutional Ring Study

Simple Summary

Tumours of the mammary gland are common in humans, as in canine species. They are very heterogenous with numerous morphological variants and different biologic behaviours. In the last few decades, several efforts have been made to classify these tumours histologically and establish the level of malignancy by using histologic grading systems. However, reproducibility and diagnostic agreement of such classification and grading have been only rarely assessed. In this study, we tested the variability in diagnoses performed by 15 pathologists using the same classification and grading system. Prior to the study, pathologists agreed on guidelines regarding how to apply these systems. Pathologists worked blindly on 36 digital histologic slides of canine mammary tumours. The agreement was statistically analysed using Cohen’s kappa coefficient that, when equal to 1, indicates perfect agreement. The overall agreement in the identification of hyperplastic-dysplastic/benign/malignant lesions was substantial (kappa 0.76), while outcomes on morphological classification had only a moderate agreement (k = 0.54). Tumour grade assigned by pathologists was the least concordant and kappa could not be calculated. Although promising, the results underline that each diagnostic/grading system should be assessed and optimized for standardization and high diagnostic agreement.

Abstract

Histological diagnosis of Canine Mammary Tumours (CMTs) provides the basis for proper treatment and follow-up. Nowadays, its accuracy is poorly understood and variable interpretation of histological criteria leads to a lack of standardisation and impossibility to compare studies. This study aimed to quantify the reproducibility of histological diagnosis and grading in CMTs. A blinded ring test on 36 CMTs was performed by 15 veterinary pathologists with different levels of education, after discussion of critical points on the Davis-Thompson Foundation Classification and providing consensus guidelines. Kappa statistics were used to compare the interobserver variability. The overall concordance rate of diagnostic interpretations of WP on identification of hyperplasia-dysplasia/benign/malignant lesions showed a substantial agreement (average k ranging from 0.66 to 0.82, with a k-combined of 0.76). Instead, outcomes on ICD-O-3.2 morphological code /diagnosis of histotype had only a moderate agreement (average k ranging from 0.44 and 0.64, with a k-combined of 0.54). The results demonstrated that standardised classification and consensus guidelines can produce moderate to substantial agreement; however, further efforts are needed to increase this agreement in distinguishing benign versus malignant lesions and in histological grading.

Artificial neural network in the discrimination of lung cancer based on infrared spectroscopy

Given the increasing prevalence of lung cancer worldwide, an auxiliary diagnostic method is needed alongside the microscopic examination of biopsy samples, which is dependent on the skills and experience of pathologists. Thus, this study aimed to advance lung cancer diagnosis by developing five (5) artificial neural network (NN) models that can discriminate malignant from benign samples based on infrared spectral data of lung tumors (n = 122; 56 malignant, 66 benign). NNs were benchmarked with classical machine learning (CML) models. Stratified 10-fold cross-validation was performed to evaluate the NN models, and the performance metrics—area under the curve (AUC), accuracy (ACC) positive predictive value (PPV), negative predictive value (NPV), specificity rate (SR), and recall rate (RR)—were averaged for comparison. All NNs were able to outperform the CML models, however, support vector machine is relatively comparable to NNs. Among the NNs, CNN performed best with an AUC of 92.28% ± 7.36%, ACC of 98.45% ± 1.72%, PPV of 96.62% ± 2.30%, NPV of 90.50% ± 11.92%, SR of 96.01% ± 3.09%, and RR of 89.21% ± 12.93%. In conclusion, NNs can be potentially used as a computational tool in lung cancer diagnosis based on infrared spectroscopy of lung tissues.

Recent Advances in the Diagnosis and Management of Multiple Primary Lung Cancer

With the wide application of computed tomography in lung cancer screening, the incidence of multiple primary lung cancer (MPLC) has been increasingly reported. Despite the established criteria, the differentiation between MPLC and intrapulmonary metastasis remains challenging. Although histologic features are helpful in some circumstances, a molecular analysis is often needed. The application of next-generation sequencing could aid in distinguishing MPLCs from intrapulmonary metastasis, decreasing ambiguity. For MPLC management, surgery with lobectomy is the main operation method. Limited resection does not appear to negatively affect survival, and it is a reasonable alternative. Stereotactic ablative radiotherapy (SABR) has become a standard of care for patients refusing surgery or for those with medically inoperable early-stage lung cancer. However, the efficacy of SABR in MPLC management could only be found in retrospective series. Other local ablation techniques are an emerging alternative for the control of residual lesions. Furthermore, systemic therapies, such as targeted therapy for oncogene-addicted patients, and immunotherapy have shown promising results in MPLC management after resection. In this paper, the recent advances in the diagnosis and management of MPLC are reviewed.

Pearls and Pitfalls in Lung Cancer Imaging

Imaging plays an essential role in the diagnosis and staging of pulmonary malignancy. Familiarity of less common manifestations of lung cancer including subsolid nodule, consolidation, and cyst associated lung cancer is important to avoid delayed diagnosis and improve patient outcomes. In this article, we review the staging of multifocal lung cancer, PET negative lung cancers (carcinoid and indolent lung adenocarcinoma), and false positive lymph nodes on PET due to infectious and inflammatory etiologies. Knowledge of these potential pitfalls and pearls in lung cancer imaging and correlation with patients' clinical history are essential to prevent misinterpretation.

Integrating NGS-derived mutational profiling in the diagnosis of multiple lung adenocarcinomas

MICROABSTRACT

Integration of Next Generation Sequencing (NGS) information for use in distinguishing between Multiple Primary Lung Cancer and intrapulmonary metastasis was evaluated. We used a probabilistic model, comprehensive histologic assessment and NGS to classify patients. Integrating NGS data confirmed initial diagnosis (n = 41), revised the diagnosis (n = 12), while resulted in non-informative data (n = 8). Accuracy of diagnosis can be significantly improved with integration of NGS data.

BACKGROUND

Distinguishing between multiple primary lung cancers (MPLC) and intrapulmonary metastases (IPM) is challenging. The goal of this study was to evaluate how Next Generation Sequencing (NGS) information may be integrated in the diagnostic strategy.

PATIENTS AND METHODS

Patients with multiple lung adenocarcinomas were classified using both the comprehensive histologic assessment and NGS. We computed the joint probability of each pair having independent mutations by chance (thus being classified as MPLC). These probabilities were computed using the marginal mutation rates of each mutation, and the known negative dependencies between driver genes and different gene loci. With these NGS-driven data, cases were re-classified as MPLC or IPM.

RESULTS

We analyzed 61 patients with a total of 131 tumors. The most frequent mutation was KRAS (57.3%) which occured at a rate higher than expected (p < 0.001) in lung cancer. No mutation was detected in 25/131 tumors (19.1%). Discordant molecular findings between tumor sites were found in 46 patients (75.4%); 11 patients (18.0%) had concordant molecular findings, and 4 patients (6.6%) had concordant molecular findings at 2 of the 3 sites. After integration of the NGS data, the initial diagnosis was confirmed for 41 patients (67.2%), the diagnosis was revised for 12 patients (19.7%) or was considered as non-informative for 8 patients (13.1%).

CONCLUSION

Integrating the information of NGS data may significantly improve accuracy of diagnosis and staging.

[Multiple synchronous lung adenocarcinoma: Interest of molecular biology for staging]

INTRODUCTION

The presence of multiple synchronous lung tumors is not a rare event. Distinguishing intra-pulmonary metastases from multiple synchronous lung adenocarcinoma is a challenge for pathologists and physicians. We present observation of a patient with three lung tumors corresponding to three adenocarcinomas for which molecular analysis had a significant impact on tumor staging.

OBSERVATION

Three suspect lesions were discovered in a 61-year-old patient, a smoker, in each lobe of the right lung. Right pneumonectomy with lymph node dissection was performed. Pathological examination showed that each tumor was in fact an adenocarcinoma. In order to more precisely indicate tumor staging, molecular analysis was performed with next generation sequencing showing a different point mutation in a driver gene on each tumor. The final diagnosis is that the three tumors are distinct synchronous tumors, which must be staged separately.

CONCLUSIONS

In modern-day practice of thoracic oncology and of surgical pathology, molecular biology represents a complement for tumor staging in the event of multiple lung tumors.

Mutational landscape of multiple primary lung cancers and its correlation with non-intrinsic risk factors

Multiple primary lung cancers (MPLCs) harbour various genetic profiles among the tumours, even from individuals with same non-intrinsic risk factors. Paired mutational analyses were performed to obtain a census of mutational events in MPLC and assess their relationship with non-intrinsic risk factors. Thirty-eight surgical specimens from 17 patients diagnosed as MPLC were used. Extracted DNAs were sequenced for somatic mutations in 409 cancer-associated genes from a comprehensive cancer panel. We statistically analysed the correlation between each driver mutation frequency and non-intrinsic risk factors using Fisher's exact test, and whether genetic mutations occurred concomitantly or randomly in MPLC using an exact test. Comprehensive genetic analyses suggested different mutation profiles in tumours within the same individuals, with some exceptions. EGFR, KRAS, TP53, or PARP1 mutations were concomitantly detected in some MPLC cases. EGFR mutations were significantly more frequent in never or light smokers and females. Concomitant EGFR or KRAS mutations in MPLCs were significantly more frequent than expected by chance (P = .0023 and .0049, respectively) suggesting a more prominent role of non-intrinsic risk factors in EGFR and KRAS mutations than other mutations, which occurred more randomly. Concomitant EGFR or KRAS mutations were particularly prominent in never or light smokers and males.

Morphological and genetic heterogeneity of synchronous multifocal lung adenocarcinoma in a Chinese cohort

Background

Synchronous multifocal lung cancer (SMLC) is diagnosed with increasing frequency in clinical practice globally. Due to innate variation in clinical management and outcome, it is vital to properly distinguish between synchronous multifocal primary lung cancer (SMPLC) and intrapulmonary metastasis (IM). The pathologic features and principal classification criteria of multifocal lung cancer remain unclear. Our objective was to evaluate the diagnostic value of histological morphologic features and driver gene mutations in SMLC classification.

Methods

We collected a unique cohort of Chinese patients with SMLC, and fully explored the morphologic, immunohistochemical, and molecular features of the disease. Twenty-one SMLC patients with a total of 50 tumours were included in our study. The pathological features that were presented by these patients were analysed, including the tumours location, tumours size, pathological types, predominant pattern of adenocarcinoma, and immunohistochemical staining. We conducted molecular testing of nine driver oncogenes that are associated with lung cancer, namely, EGER, KRAS, BRAF, NRAS, ALK, ROS1, RET, HER2, and PIK3CA.

Results

According to the Martini-Melamed classification and refined standard, 8 and 17 patients, respectively, were considered to have SMPLCs. Gene mutations were identified in 18 tumours (36%). Twelve patients had different gene mutations.

Conclusions

We demonstrate that conventional morphological assessment is not sufficient to clearly establish the clonal relationship of SMPLCs. Instead, the evaluation of histological subtypes, including nonmucinous adherent components, is required. Multiplex genotypic analysis may also prove to be a useful additional tool.

A multidisciplinary approach for the differential diagnosis between multiple primary lung adenocarcinomas and intrapulmonary metastases

PURPOSE

The distinction between multiple primary lung cancers (MPLCs) and intrapulmonary metastases has a significant impact on tumor staging and therapeutic choices. Several criteria have been proposed to solve this diagnostic issue, but a definitive consensus is still missing. We tested the efficacy of a combined clinical, histopathological and molecular ("real world") approach for the correct classification of multiple lung tumors in a selected cohort of patients.

METHODS

24 multiple lung tumors with a diagnosis of adenocarcinoma from 10 patients were retrospectively reviewed. Radiological, pathological and clinical information, including follow-up, were integrated with molecular profiling via a routine multigene panel sequencing.

RESULTS

Comprehensive histologic assessment revealed readily distinguishable histologic patterns between multiple tumors suggesting unrelated lesions in 7 cases, in agreement with clinical, radiological and molecular data, thus leading to final diagnosis of MPLCs. In the remaining 3 cases, the differential diagnosis between MPLCs and intrapulmonary metastases was challenging, since the histologic features of the lesions were similar or identical. The final interpretation (2 MPLCs and 1 most likely intrapulmonary metastases) was reached thanks to the integration of all available data, and was confirmed by follow-up.

CONCLUSIONS

A multidisciplinary approach including a routinely affordable multigene panel sequencing is a useful tool to discriminate MPLCs from intrapulmonary metastases in multiple lung nodules sharing the adenocarcinoma histotype.

Mucinous Cell Clusters in Infantile Congenital Pulmonary Airway Malformations Mimic Adult Mucinous Adenocarcinoma But Are Not Associated With Poor Outcomes When Appropriately Resected

Congenital pulmonary airway malformations (CPAMs) are abnormalities of the lung arising during development. At our institution the majority of type I infantile CPAMs contain mucinous cell clusters (MCCs). The overlapping histology of MCCs and adult in situ mucinous adenocarcinomas, as well as reports of metastatic mucinous adenocarcinoma arising in CPAMs resected later in childhood raise concerns about the malignant potential of these cells. However, after adequate surgical resection, malignant recurrence has not been reported in infants with CPAMs. Despite benign behavior, MCCs often have histologic features that, in an adult, would be consistent with a diagnosis of adenocarcinoma. Therefore, to assess the spectrum of features that may be seen in these presumed precursor lesions, we characterized the histology of 671 MCCs spread across 44 infantile CPAMs and compared them to 10 adult mucinous adenocarcinomas. MCCs in CPAMS were often numerous, widespread, and located outside of the large cysts. Mucinous and nonmucinous epithelium within CPAMs showed complex architecture, making application of adult adenocarcinoma architectural patterns difficult. The MCCs within CPAMs displayed nuclear features similar to adult mucinous adenocarcinomas. The proliferative index in infantile MCCs was higher than in adult mucinous adenocarcinomas but was also higher in uninvolved infantile lung tissue. This work illustrates that histologic features typically associated with adenocarcinoma frequently occur within CPAMs; however, this does not alter their benign behavior. Therefore, extreme caution should be used if adult lung cancer terminology is applied to avoid significant potential psychological and physical harms associated with the label of adenocarcinoma.

Distinguishing multiple lung primaries from intra-pulmonary metastases and treatment implications

INTRODUCTION

The distinction between multiple primary lung cancers and intra-pulmonary metastases has been extensively investigated because of its important clinical and therapeutic implications.

AREAS COVERED

Rapidly improving imaging technology and genomic analysis has led to a finer discrimination between multiple primary lung tumors and pulmonary metastases. However, over the past few decades, standardized criteria for the identification of multiple lung tumors have been lacking. Therefore, in 2017 a multidisciplinary international committee composed of the Union for International Cancer Control (UICC), American Joint Committee on Cancer (AJCC) and International Association for the Study of Lung Cancer (IASLC) addressed this problem when drawing up the 8th edition of TMN stage classification, that now represents a specific consensus on this topic. The most advanced diagnostic strategies associated with screening allow for the detection of early stage synchronous lung cancers.

EXPERT OPINION

Although diagnostic confirmation relies on pathologic and clinical examination, new molecular analyses help in the discrimination between primary and secondary tumors. The treatment of multiple primary lung tumors remains, whenever possible, a local treatment based on surgical resection, providing the absence of distant or local (lymph node) metastases.

Pathologists should probably forget about kappa. Percent agreement, diagnostic specificity and related metrics provide more clinically applicable measures of interobserver variability

Kappa statistics have been widely used in the pathology literature to compare interobserver diagnostic variability (IOV) among different pathologists but there has been limited discussion about the clinical significance of kappa scores. Five representative and recent pathology papers were queried using clinically relevant specific questions to learn how IOV was evaluated and how the clinical applicability of results was interpreted. The papers supported our anecdotal impression that pathologists usually assess IOV using Cohen's or Fleiss' kappa statistics and interpret the results using some variation of the scale proposed by Landis and Koch. The papers did not cite or propose specific guidelines to comment on the clinical applicability of results. The solutions proposed to decrease IOV included the development of better diagnostic criteria and additional educational efforts, but the possibility that the entities themselves represented a continuum of morphologic findings rather than distinct diagnostic categories was not considered in any of the studies. A dataset from a previous study of IOV reported by Thunnissen et al. was recalculated to estimate percent agreement among 19 international lung pathologists for the diagnosis of 74 challenging lung neuroendocrine neoplasms. Kappa scores and diagnostic sensitivity, specificity, positive and negative predictive values were calculated using the majority consensus diagnosis for each case as the gold reference diagnosis for that case. Diagnostic specificity estimates among multiple pathologists were > 90%, although kappa scores were considerably more variable. We explain why kappa scores are of limited clinical applicability in pathology and propose the use of positive and negative percent agreement and diagnostic specificity against a gold reference diagnosis to evaluate IOV among two and multiple raters, respectively.

Synchronous Pulmonary Adenocarcinomas

OBJECTIVES

To determine concordance/discordance between morphology and molecular testing (MT) among synchronous pulmonary carcinomas using targeted next generation sequencing (NGS), with and without comprehensive molecular review (CMR), vs analyses of multiple singe genes (non-NGS).

METHODS

Results of morphologic and MT assessment were classified as concordant, discordant, or indeterminate. For discordant cases, comprehensive histologic assessment (CHA) was performed.

RESULTS

Forty-seven cases with 108 synchronous tumors were identified and underwent MT (NGS, n = 23 and non-NGS, n = 24). Histology and MT were concordant, discordant, and indeterminate in 53% (25/47), 21% (10/47), and 26% (12/47) of cases, respectively. CHA of the 10 discordant cases revised results of three cases.

CONCLUSIONS

There is discordance between histology and MT in a subset of cases and MT provides an objective surrogate for staging synchronous tumors. A limited gene panel is sufficient for objectively assessing a relationship if the driver mutations are distinct. Relatedness of mutations require CMR with a larger NGS panel (eg, 50 genes).

ATR-FTIR spectroscopy as adjunct method to the microscopic examination of hematoxylin and eosin-stained tissues in diagnosing lung cancer

Lung cancer remains the leading cause of cancer-related death worldwide. Since prognosis and treatment outcomes rely on fast and accurate diagnosis, there is a need for more cost-effective, sensitive, and specific method for lung cancer detection. Thus, this study aimed to determine the ability of ATR-FTIR in discriminating malignant from benign lung tissues and evaluate its concordance with H&E staining. Three (3) 5μm-thick sections were cut from formalin fixed paraffin embedded (FFPE) cell or tissue blocks from patients with lung lesions. The outer sections were H&E-stained and sent to two (2) pathologists to confirm the histopathologic diagnosis. The inner section was deparaffinized by standard xylene method and then subjected to ATR-FTIR analysis. Distinct spectral profiles that distinguished (p<0.05) one sample from another, called the "fingerprint region", were observed in five (5) peak patterns representing the amides, lipids, and nucleic acids. Principal component analysis and hierarchical cluster analysis evidently clustered the benign from malignant tissues. ATR-FTIR showed 97.73% sensitivity, 92.45% specificity, 94.85% accuracy, 91.49% positive predictive value and 98.00% negative predictive value in discriminating benign from malignant lung tissue. Further, strong agreement was observed between histopathologic readings and ATR-FTIR analysis. This study shows the potential of ATR-FTIR spectroscopy as a potential adjunct method to the gold standard, the microscopic examination of hematoxylin and eosin (H&E)-stained tissues, in diagnosing lung cancer.

Metachronous primary lung adenocarcinomas harboring distinct KRAS mutations

To distinguish whether multiple lung nodules represent multiple primary lung cancers (MPLC) or intrapulmonary metastases (IPM) is crucial for staging and subsequent therapy. We herein present the first report of a patient with two simultaneously resected metachronous lung adenocarcinomas in the right upper lobe, each with a distinct driver mutation in the KRAS gene identified by targeted next generation sequencing (NGS). The nodules appeared chronologically metachronous, with a 3.7 year interval. Histopathology showed two histologically identical adenocarcinomas, without lymph node metastases. It was hard to decide whether they should be classified as either MPLC or IPM based only on the clinicopathological criteria. Sequencing further revealed distinct KRAS mutation in each tumor, with one tumor harboring the KRAS‐G12C mutation, and the other tumor harboring the KRAS‐Q61H mutation. Incorporation of the molecular data cleared the confusion with regard to staging and spared this patient from adjuvant therapy. This case highlights that molecular profiling allows for better differentiation between MPLC and IPM than histopathology alone.

Key points

To the best of our knowledge, this is the first case of multiple primary lung cancers harboring distinct KRAS mutations.

The case highlights the importance of incorporating molecular profiling using NGS along with the clinicopathological criteria in classifying multiple lung tumors.

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.

Molecular profiling of key driver genes improves staging accuracy in multifocal non-small cell lung cancer

OBJECTIVE

Multifocal non-small cell lung cancer has historically been separated into synchronous primary lung cancers or intrapulmonary metastases with the use of histopathology. We hypothesize that using targeted next-generation sequencing of key driver mutations in multifocal non-small cell lung cancer will improve our ability to differentiate intrapulmonary metastases from synchronous primary lung cancers.

METHODS

We identified patients who underwent surgery for non-small cell lung cancer between 2013 and 2018 with multifocal tumors. Archived specimens were reviewed with a 4-gene next-generation sequencing panel identifying mutations of EGFR, KRAS, BRAF, and NRAS. Synchronous primary lung cancers were classified as lesions with different histopathologic subtypes or driver mutations. Tests of hypotheses were performed with the Fisher exact test. Calculations were performed in Stata (v13.0; StataCorp LLC, College Station, Tex).

RESULTS

A total of 18 patients had non-small cell lung cancer tumor specimens (n = 41) available from 2 or more sites. The pathologic diagnosis was predominantly adenocarcinoma (39/41 specimens). We detected a driver mutation in 68.3% (28/41) of all tumors. The most common mutations observed were in KRAS (n = 17/41) and EGFR (n = 7/41). Eleven patients had synchronous primary lung cancers, and 4 patients had intrapulmonary metastases based on combined histopathologic and molecular profiling results. Three lacked driver mutations in either lesion. Eight synchronous primary lung cancers (8/18, 44%) were downstaged when compared with their original diagnosis (P = .08). Of these, 4 patients received adjuvant chemotherapy unnecessarily in hindsight.

CONCLUSIONS

Molecular non-small cell lung cancer profiling using a 4-gene next-generation sequencing panel allows for better distinction between synchronous primary lung cancers and intrapulmonary metastases than histopathology alone. Routine use of next-generation sequencing for multifocal lesions prevents unnecessary adjuvant treatment for patients with histologically similar synchronous primary lung cancers.

Pathology in the era of "Personalized Medicine": The need to learn how to integrate multivariate immunohistochemical and "omics" data with clinicopathologic information in a clinically relevant way"

"Personalized medicine" has been proposed as a new paradigm for patient care that, based on the integration of genomics and other "omics" data with clinical and other multidisciplinary information, promises early disease detection, improved outcomes and reduced side effects to therapies. Pathologists have become important participants in this new approach as the guardians of tissues and experts in the performance of molecular and other laboratory tests. Large amounts of new laboratory data in multiple neoplasms and other entities are being reported but there has been limited discussion about how best to evaluate the clinical significance of this information and how to integrate it into currently available diagnostic and therapeutic modalities. This article introduces a variety of epistemological problems presented by the "personalized medicine" paradigm and briefly discusses various topics that will be evaluated in further detail in future articles of this new series on Evidence-Based Pathology.

A Novel Algorithm to Differentiate Between Multiple Primary Lung Cancers and Intrapulmonary Metastasis in Multiple Lung Cancers With Multiple Pulmonary Sites of Involvement

INTRODUCTION

Differentiating between multiple primary lung cancer (MPLC) and intrapulmonary metastasis (IPM) is critical for developing a therapeutic strategy to treat multiple lung cancers with multiple pulmonary sites of involvement.

METHODS

We retrospectively included 252 lesions (126 pairs) from 126 patients with surgically resected multiple lung adenocarcinomas. Each pair was classified as MPLC or IPM based on histopathologic findings as the reference standard. A novel algorithm was established with four sequential decision steps based on the combination of computed tomography (CT) lesion types (step 1), CT lesion morphology (step 2), difference of maximal standardized uptake values on positron-emission tomography/CT (step 3), and presence of N2/3 lymph node metastasis or distant metastasis (step 4). The diagnostic accuracy of the algorithm was analyzed. Performances of 11 observers were assessed without and with knowledge of algorithm.

RESULTS

Among 126 pairs, 90 (71.4%) were classified as MPLCs and 36 (28.6%) as IPMs. On applying the diagnostic algorithm, the overall accuracy for diagnosis of IPM among conclusive cases up to step 4 was 88.9%, and 65 and 44 pairs were correctly diagnosed based on step 1 and step 2, respectively. Specificity and positive predictive value for diagnosis of IPM increased significantly in all observers compared with reading rounds without the algorithm.

CONCLUSIONS

Application of the algorithm based on comprehensive information on clinical and imaging variables can allow differentiation between MPLCs and IPMs. When both of two suspected malignant lesions appear as solid predominant lesions without spiculation or air-bronchogram on CT, IPM should be considered.

Clonality analysis of pulmonary tumors by genome-wide copy number profiling

Multiple tumors in patients are frequently diagnosed, either synchronous or metachronous. The distinction between a second primary and a metastasis is important for treatment. Chromosomal DNA copy number aberrations (CNA) patterns are highly unique to specific tumors. The aim of this study was to assess genome-wide CNA-patterns as method to identify clonally related tumors in a prospective cohort of patients with synchronous or metachronous tumors, with at least one intrapulmonary tumor. In total, 139 tumor pairs from 90 patients were examined: 35 synchronous and 104 metachronous pairs. Results of CNA were compared to histological type, clinicopathological methods (Martini-Melamed-classification (MM) and ACCP-2013-criteria), and, if available, EGFR- and KRAS-mutation analysis. CNA-results were clonal in 74 pairs (53%), non-clonal in 33 pairs (24%), and inconclusive in 32 pairs (23%). Histological similarity was found in 130 pairs (94%). Concordance between histology and conclusive CNA-results was 69% (74 of 107 pairs: 72 clonal and two non-clonal). In 31 of 103 pairs with similar histology, genetics revealed non-clonality. In two out of four pairs with non-matching histology, genetics revealed clonality. The subgroups of synchronous and metachronous pairs showed similar outcome for the comparison of histological versus CNA-results. MM-classification and ACCP-2013-criteria, applicable on 34 pairs, and CNA-results were concordant in 50% and 62% respectively. Concordance between mutation matching and conclusive CNA-results was 89% (8 of 9 pairs: six clonal and two non-clonal). Interestingly, in one patient both tumors had the same KRAS mutation, but the CNA result was non-clonal. In conclusion, although some concordance between histological comparison and CNA profiling is present, arguments exist to prefer extensive molecular testing to determine whether a second tumor is a metastasis or a second primary.

Prognostic Impact of Tumor Doubling Time in Patients with Metachronous Lung Cancer

BACKGROUND

Good prognosis following surgery for metachronous lung cancer has been reported. However, prognostic factors have not been fully investigated. The purpose of this study was to identify the preoperative predictor of survival in metachronous lung cancer.

METHODS

Patients who underwent a second pulmonary resection for metachronous lung cancer at our institution between 2000 and 2014 were analyzed.

RESULTS

A retrospective chart review identified 86 eligible patients (of 6213; 1.4%). The 5-year overall survival was 77%. All 86 cancers met Martini and Melamed's criteria for second primary cancer. However, on pathological examination based on morphological concordance between the initial and metachronous cancer, 73 (85%) cases were diagnosed as second primary cancer and 13 (15%) as a possible recurrent tumor. The 5-year overall survivals were 82% for second primary cancers and 52% for possible recurrent tumors. Tumor doubling time > 180 days (p < 0.001), pathological diagnosis of second primary cancer (p = 0.013), pathological stage IA (p = 0.016), interval between resections > 2 years (p = 0.040), and consolidation/tumor diameter ratio ≤ 0.5 (p = 0.045) were associated with superior overall survival. Multivariate Cox regression analysis identified tumor doubling time > 180 days as the only independent predictor of overall survival (hazard ratio 3.600, 95% confidence interval 1.226-10.338; p = 0.0196).

CONCLUSIONS

Surgical resection for metachronous lung cancer is effective and feasible. Particularly, a tumor doubling time > 180 days is associated with superior survival in patients with metachronous lung cancer.

Chemotherapy in Combination With Immune Checkpoint Inhibitors for the First-Line Treatment of Patients With Advanced Non-small Cell Lung Cancer: A Systematic Review and Literature-Based Meta-Analysis

Background: Checkpoint inhibitors plus platinum-based chemotherapy have shown superiority compared to chemotherapy alone as first-line therapy in advanced non–small cell lung carcinoma (NSCLC). To evaluate the relative benefit in term of Overall Survival (OS) and Progression-free Survival (PFS) of checkpoint inhibitors plus chemotherapy vs. chemotherapy alone, overall and in subgroups defined by PDL1 expression we have performed a meta-analysis.

Data Sources: This meta-analysis searched PubMed and checked references of the selected English language articles to identify further eligible trials. Data collection for this study took place from October 1 to October 24, 2018.

Results: In total, 8 trials involving 4,646 patients with advanced NSCLC, 3.314 (71%) and 1.332 (29%) with a non-squamous and squamous histology, respectively, were included in this meta-analysis. Four trials used atezolizumab, 3 pembrolizumab, and 1 nivolumab, accounting for 2.985 (64%), 1.298 (28%), and 363 (8%) of patients, respectively. The patients were randomized to receive first-line chemotherapy plus a checkpoint inhibitor vs. first-line chemotherapy, 2,978 patients for the OS endpoint and first-line chemotherapy plus a checkpoint inhibitor vs. first-line chemotherapy, 1,740 patients in the PFS endpoint. Checkpoint inhibitors plus chemotherapy were associated with prolonged OS, compared with chemotherapy in the ITT population (HR, 0.74; 95% CI, 0.64–0.87; p = 0.0002, with significant heterogeneity among trials). Notably within the PDL1 low group (1–49) there was a significant heterogeneity (p = 0.06) between type of drug and efficacy: the combination of chemotherapy plus pembrolizumab showed an OS benefit (HR, 0.56; 95% CI, 0.40–0.78; P < 0.00007) unlike the atezolizumab backbone trials (HR, 0.92; 95% CI, 0.62–1.37; P < 0.69). However, checkpoint inhibitors plus chemotherapy were associated with prolonged PFS in the ITT (HR, 0.61; 95% CI, 0.56–0.66; P < 0.00001) and across PDL1 subgroups.

Conclusion and Relevance: Checkpoint inhibitors plus chemotherapy compared with chemotherapy, are associated with significantly prolonged OS and PFS in first-line therapy in NSCLC. In the low PDL1 subgroups the benefit was statistically significant only in the pembrolizumab backbone trials. The findings of this meta-analysis could assist in the design and interpretation of future trials and in economic analyses.

Progress in the Management of Early-Stage Non-Small Cell Lung Cancer in 2017

The landscape of care for early-stage non-small cell lung cancer continues to evolve. While some of the developments do not seem as dramatic as what has occurred in advanced disease in recent years, there is a continuous improvement in our ability to diagnose disease earlier and more accurately. We have an increased understanding of the diversity of early-stage disease and how to better tailor treatments to make them more tolerable without impacting efficacy. The International Association for the Study of Lung Cancer and the Journal of Thoracic Oncology publish this annual update to help readers keep pace with these important developments. Experts in the care of early-stage lung cancer patients have provided focused updates across multiple areas including screening, pathology, staging, surgical techniques and novel technologies, adjuvant therapy, radiotherapy, surveillance, disparities, and quality of life. The source for information includes large academic meetings, the published literature, or novel unpublished data from other international oncology assemblies.