Histopathological and molecular study for synchronous lung adenocarcinoma staging

Multidisciplinary expert consensus on diagnosis and treatment of multiple lung cancers

The rising incidence of multiple lung cancers (MLCs), encompassing multiple primary lung cancers (MPLCs) and intrapulmonary metastasis (IPM), poses two significant clinical challenges. First, distinguishing between MPLC and IPM remains difficult due to insufficiently accurate criteria and ambiguous integration of genetic testing. Second, standardized therapeutic protocols are still lacking. To address these issues, the Lung Cancer Expert Committee of China Anti-Cancer Association (CACA) assembled a multidisciplinary expert panel spanning thoracic surgery, pulmonary medicine, oncology, radiology, and pathology. Following a comprehensive literature review ending on October 23, 2024, the panel engaged in iterative discussions and conducted two rounds of expert voting, culminating in 25 evidence-based recommendations across five key domains: epidemiology, pre-treatment evaluation, definitive diagnostics, surgical treatment, and non-surgical treatment. This consensus provides clinicians with practical guidance to enhance diagnostic precision and therapeutic decision-making in MLC management while highlighting unmet needs to inform future guideline development.

Differentiating Separate Primary Lung Adenocarcinomas From Intrapulmonary Metastases With Emphasis on Pathological and Molecular Considerations: Recommendations From the International Association for the Study of Lung Cancer Pathology Committee

INTRODUCTION

With the implementation of low-dose computed tomography screening, multiple pulmonary tumor nodules are diagnosed with increasing frequency and the selection of surgical treatments versus systemic therapies has become challenging on a daily basis in clinical practice. In the presence of multiple carcinomas, especially adenocarcinomas, pathologically determined to be of pulmonary origin, the distinction between separate primary lung carcinomas (SPLCs) and intrapulmonary metastases (IPMs) is important for staging, management, and prognostication.

METHODS

We systemically reviewed various means that aid in the differentiation between SPLCs and IPMs explored by histopathologic evaluation and molecular profiling, the latter includes DNA microsatellite analysis, array comparative genomic hybridization, TP53 and oncogenic driver mutation testing and, more recently, with promising effectiveness, next-generation sequencing comprising small- or large-scale multi-gene panels.

RESULTS

Comprehensive histologic evaluation may suffice to differentiate between SPLCs and IPMs. Nevertheless, molecular profiling using larger-scale next-generation sequencing typically provides superior discriminatory power, allowing for more accurate classification. On the basis of the literature review and expert opinions, we proposed a combined four-step histologic and molecular classification algorithm for addressing multiple pulmonary tumor nodules of adenocarcinoma histology that encourages a multidisciplinary approach. It is also noteworthy that new technologies combining machine learning and digital pathology may develop into valuable diagnostic tools for distinguishing SPLCs from IPMs in the future.

CONCLUSIONS

Although histopathologic evaluation is often adequate to differentiate SPLCs from IPMs, molecular profiling should be performed when possible, especially in cases with tumors exhibiting similar morphology. This manuscript summarized the previous efforts in resolving the current challenges and highlighted the recent progress in the differentiation methods and algorithms used in categorizing multiple lung adenocarcinomas into SPLCs or IPMs, which are becoming more and more critical in precision lung cancer management.

Next-Generation Sequencing vs. Clinical-Pathological Assessment in Diagnosis of Multiple Lung Cancers: A Systematic Review and Meta-Analysis

Accurately distinguishing between multiple primary lung cancers (MPLC) and intrapulmonary metastasis (IPM) is crucial for tailoring treatment strategies and improving patient outcomes. While molecular methods offer significant advantages over traditional clinical-pathological evaluations, they lack standardized diagnostic protocols and validated prognostic value. This study systematically compared the diagnostic and prognostic performance of molecular methods versus clinical-pathological evaluations in diagnosing multiple lung cancers (MLCs), specifically focusing on the impact of next-generation sequencing (NGS) parameters on diagnostic accuracy. A review of 41 studies encompassing 1266 patients revealed that two molecular methods, Mole1 (manually counting shared mutations) and Mole2 (bioinformatics-assisted clonal probability calculation), both demonstrated superior diagnostic accuracy and prognostic discrimination capabilities. Molecular assessment, particularly Mole1, effectively stratified prognosis for MPLC and IPM, leading to significantly improved disease-free survival (DFS: HR = 0.24, 95% CI: 0.15-0.39) and overall survival (OS: HR = 0.33, 95% CI: 0.18-0.58). Further analysis suggests that a minimal panel of 30-50 genes may be sufficient to effectively differentiate prognoses. Compared to Mole1, Mole2 demonstrated greater specificity and stability across various panels, achieving AUC values from 0.962 to 0.979. Clinical-pathological evaluations proved unreliable, not only failing to distinguish prognosis effectively but also exhibiting a potential misdiagnosis rate of 35.5% and 33.6% compared to the reference diagnosis. To improve both cost-effectiveness and diagnostic accuracy, bioinformatics-assisted molecular diagnostics should be integrated into multidisciplinary assessments, especially for high-risk cases where diagnostic errors are common.

Optimizing the NGS-based discrimination of multiple lung cancers from the perspective of evolution

Next-generation sequencing (NGS) offers a promising approach for differentiating multiple primary lung cancers (MPLC) from intrapulmonary metastasis (IPM), though panel selection and clonal interpretation remain challenging. Whole-exome sequencing (WES) data from 80 lung cancer samples were utilized to simulate MPLC and IPM, with various sequenced panels constructed through gene subsampling. Two clonal interpretation approaches primarily applied in clinical practice, MoleA (based on shared mutation comparison) and MoleB (based on probability calculation), were subsequently evaluated. ROC analysis highlighted MoleB's superior performance, especially with the NCCNplus panel (AUC = 0.950 ± 0.002) and pancancer MoleA (AUC = 0.792 ± 0.004). In two independent cohorts (WES cohort, N = 42 and non-WES cohort, N = 94), NGS-based methodologies effectively stratified disease-free survival, with NCCNplus MoleB further predicting prognosis. Phylogenetic analysis further revealed evolutionary distinctions between MPLC and IPM, establishing an optimized NGS-based framework for differentiating multiple lung cancers.

Pathologic Assessment and Staging of Multiple Non-Small Cell Lung Carcinomas: A Paradigm Shift with the Emerging Role of Molecular Methods

Non-small cell lung carcinomas (NSCLCs) commonly present as 2 or more separate tumors. Biologically, this encompasses 2 distinct processes: separate primary lung carcinomas (SPLCs), representing independently arising tumors, and intrapulmonary metastases (IPMs), representing intrapulmonary spread of a single tumor. The advent of computed tomography imaging has substantially increased the detection of multifocal NSCLCs. The strategies and approaches for distinguishing between SPLCs and IPMs have evolved significantly over the years. Recently, genomic sequencing of somatic mutations has been widely adopted to identify targetable alterations in NSCLC. These molecular techniques have enabled pathologists to reliably discern clonal relationships among multiple NSCLCs in clinical practice. However, a standardized approach to evaluating and staging multiple NSCLCs using molecular methods is still lacking. Here, we reviewed the historical context and provided an update on the growing applications of genomic testing as a clinically relevant benchmark for determining clonal relationships in multiple NSCLCs, a practice we have designated "comparative molecular profiling." We examined the strengths and limitations of the morphology-based distinction of SPLCs vs IPMs and highlighted pivotal clinical and pathologic insights that have emerged from studying multiple NSCLCs using genomic approaches as a gold standard. Lastly, we suggest a practical approach for evaluating multiple NSCLCs in the clinical setting, considering the varying availability of molecular techniques.

Using molecular characteristics to distinguish multiple primary lung cancers and intrapulmonary metastases

Objectives

Multiple lung cancers may present as multiple primary lung cancers (MPLC) or intrapulmonary metastasis (IPM) with variations in clinical stage, treatment, and prognosis. However, the existing differentiation criteria based on histology do not fully meet the clinical needs. Next-generation sequencing (NGS) may play an important role in assisting the identification of different pathologies. Here, we extended the relevant data by combining histology and NGS to develop detailed identification criteria for MPLC and IPM.

Materials and Methods

Patients with lung cancer (each patient had ≥2 tumors) were enrolled in the training (n = 22) and validation (n = 13) cohorts. Genomic profiles obtained from 450-gene-targeted NGS were analyzed, and the new criteria were developed based on our findings and pre-existing Martini & Melamed criteria and molecular benchmarks.

Results

The analysis of the training cohort indicated that patients identified with MPLC had no (or <2) trunk or shared mutations. However, 98.02% of mutations were branch mutations, and 69.23% of MPLC had no common mutations. In contrast, a higher percentage of trunk (33.08%) or shared (9.02%) mutations were identified in IPM, suggesting significant differences among mutated components. Subsequently, eight MPLC and five IPM cases were identified in the validation cohort, aligning with the independent imaging and pathologic distinction. Overall, the percentage of trunk and shared mutations was higher in patients with IPM than in patients with MPLC. Based on these results and the establishment of new determination criteria for MPLC and IPM, we emphasize that the type and number of shared variants based on histologic consistency assist in identification.

Conclusion

Determining genetic alterations may be an effective method for differentiating MPLC and IPM, and NGS can be used as a valuable assisting tool.

Progress in genome-inspired treatment decisions for multifocal lung adenocarcinoma

INTRODUCTION

Multifocal lung adenocarcinoma (MFLA) is becoming increasingly recognized as a distinct subset of lung cancer, with unique biology, disease course, and treatment outcomes. While definitions remain controversial, MFLA is characterized by the development and concurrent presence of multiple independent (non-metastatic) lesions on the lung adenocarcinoma spectrum. Disease progression typically follows an indolent course measured in years, with a lower propensity for nodal and distant metastases than other more common forms of non-small cell lung cancer.

AREAS COVERED

Traditional imaging and histopathological analyses of tumor biopsies are frequently unable to fully characterize the disease, prompting interest in molecular diagnosis. We highlight some of the key questions in the field, including accurate definitions to identify and stage MLFA, molecular tests to stratify patients and treatment decisions, and the lack of clinical trial data to delineate best management for this poorly understood subset of lung cancer patients. We review the existing literature and progress toward a genomic diagnosis for this unique disease entity.

EXPERT OPINION

Multifocal lung adenocarcinoma behaves differently than other forms of non-small cell lung cancer. Progress in molecular diagnosis may enhance potential for accurate definition, diagnosis, and optimizing treatment approach.

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.

Differential Diagnostic Value of Histology in MPLC and IPM: A Systematic Review and Meta-Analysis

Background

The paramount issue regarding multiple lung cancer (MLC) is whether it represents multiple primary lung cancer (MPLC) or intrapulmonary metastasis (IPM), as this directly affects both accurate staging and subsequent clinical management. As a classic method, histology has been widely utilized in clinical practice. However, studies examining the clinical value of histology in MLC have yielded inconsistent results; thus, this remains to be evaluated. Here, we performed a meta-analysis to assess the differential diagnostic value of histology in MPLC and IPM and to provide evidence-based medicine for clinical work.

Methods

PubMed, Embase, and Web of Science databases were searched to collect relevant literature according to PRISMA, and inclusion and exclusion criteria were set up to screen and assess the literature. The data required for reconstructing a 2 × 2 contingency table were extracted directly or calculated indirectly from the included studies, and statistical analysis was carried out by using Stata 15, Meta-DiSc 1.4, and Review Manager 5.4 software.

Results

A total of 34 studies including 1,075 pairs of tumors were included in this meta-analysis. Among these studies, 11 were about the M-M standard and the pooled sensitivity and specificity were 0.78 (95% CI: 0.71–0.84) and 0.47 (95% CI: 0.38–0.55), respectively; 20 studies were about CHA and the pooled sensitivity and specificity were 0.76 (95% CI: 0.72–0.80) and 0.74 (95% CI: 0.68–0.79), respectively; and 3 studies were about the “CHA & Lepidic” criteria and the pooled sensitivity and specificity were 0.96 (95% CI: 0.85–0.99) and 0.47 (95% CI: 0.21–0.73), respectively. The combined pooled sensitivity, specificity, PLR, NLR, DOR, and the area under the SROC curve of the 34 studies were 0.80 (95% CI: 0.73–0.86), 0.64 (95% CI: 0.51–0.76), 2.25 (95% CI: 1.59–3.17), 0.31 (95% CI: 0.23–0.43), 7.22 (95% CI: 4.06–12.81), and 0.81 (95% CI: 0.77–0.84), respectively.

Conclusion

The current evidence indicated that histology had a moderate differential diagnostic value between MPLC and IPM. Among the three subgroups, the “CHA & Lepidic” criteria showed the highest sensitivity and CHA showed the highest specificity. Further research is necessary to validate these findings and to improve clinical credibility.

Systematic Review Registration

PROSPERO, identifier CRD42022298180.

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.

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.

Multiple Primary Lung Cancers: A New Challenge in the Era of Precision Medicine

With the widespread implementation of lung cancer screening, more and more patients are being diagnosed with multiple primary lung cancers (MPLCs). In the era of precision medicine, many controversies remain in differentiating MPLCs from intrapulmonary metastasis and the optimum treatment choice, especially in patients exhibiting similar histology. In this review, we summarize common diagnostic criteria and novel discrimination methods with a special emphasis on the emerging value of broad panel next-generation sequencing (NGS) for the diagnosis of MPLCs. We then discuss current advances regarding therapeutic approaches for MPLCs. Radical surgery is the main treatment modality, while stereotactic body radiotherapy (SBRT) is safe and feasible for early-stage MPLC patients with inoperable tumors. In addition, immunotherapy and targeted therapy, particularly epidermal growth factor receptor-tyrosine kinase inhibitors, are emerging therapeutic strategies that are still in their infancy. Characteristics of both genomic profiles and tumor microenvironment are currently being evaluated but warrant further exploration to facilitate the application of targeted systematic therapies in MPLC patients.

Genetic features and application value of next generation sequencing in the diagnosis of synchronous multifocal lung adenocarcinoma

The present study aimed to elucidate the genetic features of multiple lung cancer (MLC) and identify effective molecular markers for diagnosis using next generation sequencing (NGS). The present data may also inform patient treatment and prognosis. A total of 35 lesions were obtained from 17 patients with MLC. Based on lesion histology and NGS, 13 cases of multiple primary lung cancer (MPLC) were identified and 4 cases were classified as intrapulmonary metastasis (IPM). All 4 patients with IPM exhibited an epidermal growth factor receptor (EGFR) mutation and synchronous mutation of at least one tumor suppressor gene. The frequency and percentage of EGFR mutations, accompanied with tumor suppressor genes, were significantly higher in patients with IPM compared with MPLC. Furthermore, a high EGFR-heterogeneity score and male sex were risk factors of IPM occurrence. There were significant differences in mean EGFR mutation abundance alone, mutations of tumor suppressor genes and mutations of EGFR combined with tumor suppressor genes between patients with adenocarcinoma (ADC) and adenocarcinoma in situ (AIS). In conclusion, histological characteristics combined with genetic alterations may be an effective method for the diagnosis of MPLC and IPM, and NGS may serve as a useful diagnostic tool. MLC exhibited unique molecular characteristics, including higher rates of EGFR mutations, EGFR driver mutations accompanied with tumor suppressor gene mutations and the absence of anaplastic lymphoma kinase mutations, which may help distinguish between patients with MPLC or IPM. The present study hypothesized that the mean frequency of EGFR mutations, mutations of tumor suppressor genes and mutations of both EGFR and tumor suppressor genes may serve an important role in the development of AIS to ADC. The results of the present study highlight the potential underlying mechanisms of lung ADC development, which may assist with future elucidation of effective treatments to prevent the progression of lung cancer.