Patterns of allelic loss of synchronous adenocarcinomas of the lung

From Morphology to Molecules: Advances in the Distinction of Multiple Primary Lung Cancers From Intrapulmonary Metastases in Non-Small Cell Lung Cancer

The increasing incidence of multiple lung nodules underscores the need for precise differentiation between multiple primary lung cancers (MPLCs) and intrapulmonary metastases (IPMs). This distinction impacts patient prognosis and treatment strategies. The prevalence of multiple lung nodules, ranging from 19.7% to 55.5%, highlights the clinical significance of this challenge. Historically, the role of histopathology, particularly comprehensive histology assessment (CHA), has been pivotal in differentiating MPLCs and IPMs. However, CHA has significant limitations, resulting in a constant search for a better way to distinguish those lesions. The best strategy for delineating MPLCs from IPMs is a multidisciplinary approach combining clinical data, radiology, histology, and molecular methods. Histology provides architectural and cellular characteristics, radiology contributes anatomic context and lesion characterization, and molecular methods reveal molecular features critical for accurate differentiation. Incorporating clinical data further enhances diagnostic precision. This review presents current knowledge and current approaches to multiple lung tumors. It is clear that even with a combination of pathology, radiology, and molecular data, definitive classification of multifocal lung tumors is not always possible.

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.

Multiple primary lung cancer: Updates of clinical management and genomic features

In recent decades, multiple primary lung cancer (MPLC) has been increasingly prevalent in clinical practice. However, many details about MPLC have not been completely settled, such as understanding the driving force, clinical management, pathological mechanisms, and genomic architectures of this disease. From the perspective of diagnosis and treatment, distinguishing MPLC from lung cancer intrapulmonary metastasis (IPM) has been a clinical hotpot for years. Besides, compared to patients with single lung lesion, the treatment for MPLC patients is more individualized, and non-operative therapies, such as ablation and stereotactic ablative radiotherapy (SABR), are prevailing. The emergence of next-generation sequencing has fueled a wave of research about the molecular features of MPLC and advanced the NCCN guidelines. In this review, we generalized the latest updates on MPLC from definition, etiology and epidemiology, clinical management, and genomic updates. We summarized the different perspectives and aimed to offer novel insights into the management of MPLC.

Two different patterns of lung adenocarcinoma with concomitant EGFR mutation and ALK rearrangement

Epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements are considered mutually exclusive in non-small cell lung cancer (NSCLC), especially in lung adenocarcinoma (LUAC). However, sporadic cases harboring concomitant EGFR and ALK alterations have been increasingly reported. There is no consensus opinion regarding the treatment of patients positive for both molecular alterations. NSCLC with EGFR/ALK coalterations should be separated into two subtypes: unifocal and multifocal LUAC. Here, we present an overview of the available literature regarding this rare group of patients to provide useful suggestions for therapeutic strategies.

A comprehensive algorithm to distinguish between MPLC and IPM in multiple lung tumors patients

Background

Diagnosis of multiple lung nodules has become convenient and frequent due to the improvement of computed tomography (CT) scans. However, to distinguish intrapulmonary metastasis (IPM) from multiple primary lung cancer (MPLC) remains challenging. Herein, for the accurate optimization of therapeutic options, we propose a comprehensive algorithm for multiple lung carcinomas based on a multidisciplinary approach, and investigate the prognosis of patients who underwent surgical resection.

Methods

Patients with multiple lung carcinomas who were treated at West China Hospital of Sichuan University from April, 2009 to December, 2017, were retrospectively identified. A comprehensive algorithm combining histologic assessment, molecular analysis, and imaging information was used to classify nodules as IPM or MPLC. The Kaplan-Meier method was used to estimate survival rates, and the relevant factors were evaluated using the log-rank test or Cox proportional hazards model.

Results

The study included 576 patients with 1,295 lung tumors in total. Significant differences were observed between the clinical features of 171 patients with IPM and 405 patients with MPLC. The final classification consistency was 0.65 and 0.72 compared with the criteria of Martini and Melamed (MM) and the American College of Chest Physicians (ACCP), respectively. Patients with independent primary tumors had better overall survival (OS) than patients with intra-pulmonary metastasis (HR =3.99, 95% CI: 2.86–5.57; P<0.001). Nodal involvement and radiotherapy were independent prognostic factors.

Conclusions

The comprehensive algorithm was a relevant tool for classifying multifocal lung tumors as MPLC or IPM, and could help doctors with precise decision-making in routine clinical practice. Patients with multiple lesions without lymph node metastasis or without radiotherapy tended to have a better prognosis.

Pathology Issues in Thoracic Oncology: Histologic Characterization and Tissue/Plasma Genotyping May Resolve Diagnostic Dilemmas

Lung cancer is a heterogeneous diagnosis that encompasses a spectrum of histologic and molecular subgroups. A paradigm shift favoring selection of treatment based on histologic and molecular makeup has positively affected prognosis for patients with metastatic lung cancer, with select patients experiencing durable responses to treatment. However, prognosis remains poor for the majority of patients. Furthermore, oncologists are increasingly faced with challenging dilemmas related to histopathologic and molecular characterization of tumors, both at diagnosis and during treatment. In this review, we focus on three particular challenges: (1) management of mixed histology tumors, a particularly aggressive group of lung cancers, (2) distinguishing multiple primary lung tumors from intrapulmonary metastases, and (3) incorporation of liquid biopsies into the diagnostic algorithm and subsequent follow-up of patients with advanced lung cancer. This review will summarize the existing literature and highlight the potential for molecular genotyping to help refine approaches to each of these challenges.

Histopathologic and molecular approach to staging of multiple lung nodules

Distinguishing multiple primary lung cancers from intrapulmonary metastases in patients with synchronous multifocal lung adenocarcinomas can be challenging. The most recent 8th edition American Joint Committee on Cancer staging manual (AJCC staging manual) distinguishes four disease patterns in patients with multiple lung nodules: (I) two or more distinct and histologically different masses (considered unrelated and staged as individual cancers); (II) multiple ground-glass or part-solid nodules, histologically of with lepidic growth pattern (considered separate tumors, T staged based on highest T stage lesion); (III) patchy areas of ground-glass and consolidations, histologically often invasive mucinous adenocarcinomas (considered single tumor with diffuse "pneumonic-type" involvement); and (IV) separate nodules with the same histologic features based on comprehensive histologic subtyping (considered intrapulmonary metastases). Histologic and molecular features, in conjunction with clinical and radiological information, can all be tools to assist with staging of multiple nodules. Histologic features of adenocarcinomas are best characterized using comprehensive histologic subtyping (percentage of lepidic, acinar, solid, papillary and micropapillary pattern). Genomic alterations are commonly assessed using fluorescence in-situ hybridization and next generation sequencing (NGS). The AJCC considers exactly matching breakpoints by comparative genomic hybridization (CGH) as the only evidence for intrapulmonary metastases, and clearly different histologic types or subtypes as the only evidence for separate primary tumors. Similar histologic subtypes or the same biomarker pattern are considered merely relative arguments in favor of a single tumor source. When assessing multifocal lung cancer, pathologists should consider, and carefully weigh the importance of, molecular testing results in addition to the tumor's histologic features. For many cases encountered in routine clinical practice, absolute certainty cannot be reached as to whether they represent multiple primary cancers or intrapulmonary metastases. Classification of difficult cases often benefits from multidisciplinary discussion.

Utility of Genomic Analysis in Differentiating Synchronous and Metachronous Lung Adenocarcinomas from Primary Adenocarcinomas with Intrapulmonary Metastasis

Distinguishing synchronous and metachronous primary lung adenocarcinomas from adenocarcinomas with intrapulmonary metastasis is essential for optimal patient management. In this study, multiple lung adenocarcinomas occurring in the same patient were evaluated using comprehensive histopathologic evaluation supplemented with molecular analysis. The cohort included 18 patients with a total of 52 lung adenocarcinomas. Eleven patients had a new diagnosis of multiple adenocarcinomas in the same lobe (n = 5) or different lobe (n = 6). Seven patients had a history of lung cancer and developed multiple new tumors. The final diagnosis was made in resection specimens (n = 49), fine needle aspiration (n = 2), and biopsy (n = 1). Adenocarcinomas were non‐mucinous, and histopathologic comparison of tumors was performed. All tumors save for one were subjected to ALK gene rearrangement testing and targeted Next Generation Sequencing (NGS). Using clinical, radiologic, and morphologic features, a confident conclusion favoring synchronous/metachronous or metastatic disease was made in 65% of patients. Cases that proved challenging included ones with more than three tumors showing overlapping growth patterns and lacking a predominant lepidic component. Genomic signatures unique to each tumor were helpful in determining the relationship of multiple carcinomas in 72% of patients. Collectively, morphologic and genomic data proved to be of greater value and achieved a conclusive diagnosis in 94% of patients. Assessment of the genomic profiles of multiple lung adenocarcinomas complements the histological findings, enabling a more comprehensive assessment of synchronous, metachronous, and metastatic lesions in most patients, thereby improving staging accuracy. Targeted NGS can identify genetic alterations with therapeutic implications.

Morphological and molecular approach to synchronous non-small cell lung carcinomas: impact on staging

Distinction between multiple primary cancers and intrapulmonary metastases in patients with synchronous multifocal lung cancer can be challenging. Histological and genotypic assessment of multifocal lung tumors have been suggested to influence the staging. The aim of this study was to determine the role of morphology and genotype in staging of surgically treated multifocal non-small cell lung carcinoma. Synchronous lung cancers from 60 patients (42 with adenocarcinoma and 18 with squamous cell carcinoma), clinically considered to represent intrapulmonary metastases, were histologically subtyped according to the 2015 World Health Organization classification of lung tumors and subjected to genotypic analysis (KRAS, EGFR, BRAF, PIK3CA, ALK, MET and ROS1 in adenocarcinoma and PIK3CA and p16 in squamous cell carcinoma). Concordance between clinical criteria and histological subtyping was identified in about 50% of cases (P<0.0001). Genotypically, 44% of adenocarcinomas and 60% of squamous cell carcinomas with identified molecular alterations were considered to be intrapulmonary metastases. Concordance between histological and molecular staging was observed in 89% of adenocarcinomas and 56% of squamous cell carcinomas. Univariate survival analyses failed to demonstrate significant differences in overall or cancer-specific survival in patients with adenocarcinoma and squamous cell carcinomas restaged according to histology and/or molecular profile. Lymph node metastases (N1/N2 vs N0) (P=0.03) and age >65 years (P=0.05) were associated with shorter overall survival. In addition, squamous cell carcinomas with p16 deletion showed shorter overall survival when compared with squamous cell carcinomas without p16 deletion (P=0.05). No correlation between other molecular alterations, clinico-pathological characteristics and prognosis was found. Our study demonstrates that a comprehensive genotypic and morphological assessment of surgically treated multifocal lung cancers is feasible but not sufficient to establish their clonal relationship and prognosis.

USING SOMATIC MUTATION DATA TO TEST TUMORS FOR CLONAL RELATEDNESS

A major challenge for cancer pathologists is to determine whether a new tumor in a patient with cancer is a metastasis or an independent occurrence of the disease. In recent years numerous studies have evaluated pairs of tumor specimens to examine the similarity of the somatic characteristics of the tumors and to test for clonal relatedness. As the landscape of mutation testing has evolved a number of statistical methods for determining clonality have developed, notably for comparing losses of heterozygosity at candidate markers, and for comparing copy number profiles. Increasingly tumors are being evaluated for point mutations in panels of candidate genes using gene sequencing technologies. Comparison of the mutational profiles of pairs of tumors presents unusual methodological challenges: mutations at some loci are much more common than others; knowledge of the marginal mutation probabilities is scanty for most loci at which mutations might occur; the sample space of potential mutational profiles is vast. In this article we examine this problem and propose a test for clonal relatedness of a pair of tumors from a single patient. Using simulations, its properties are shown to be promising. The method is illustrated using several examples from the literature.

Microsatellite alteration in multiple primary lung cancer

Patients with pulmonary neoplasms have an increased risk for developing a second tumor of the lung, either at the same time or different times. It is important to determine if the second tumor represents an independent primary tumor or recurrence/metastasis, because it will significantly change the management and prognosis. Microsatellite instability (MSI) and loss of heterozygosity (LOH) represents molecular disorders acquired by the cell during neoplastic transformation. Both are associated with genetic instability. Functional silencing of tumour suppressor genes may be the consequence of genomic instability, particularly of the globally occurring LOH phenomenon. Numerous studies have confirmed the role of MSI/LOH at both the early and the late stages of multiple primary lung cancer. This paper reviews the published literatures focused on the role of MSI/LOH significance in multiple primary lung cancer. Additionally, a new method based on the allelic variations at polymorphic microsatellite markers was offered that it does not rely on collection of normal tissue, performed with minimal tumor sample, and will complement clinical criteria for diagnostic discrimination between multiple primary cancers versus solitary metastatic diseases.

The stage classification of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

The current Lung Cancer Stage Classification system is the seventh edition, which took effect in January 2010. This article reviews the definitions for the TNM descriptors and the stage grouping in this system.

Special treatment issues in non-small cell lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

This guideline updates the second edition and addresses patients with particular forms of non-small cell lung cancer that require special considerations, including Pancoast tumors, T4 N0,1 M0 tumors, additional nodules in the same lobe (T3), ipsilateral different lobe (T4) or contralateral lung (M1a), synchronous and metachronous second primary lung cancers, solitary brain and adrenal metastases, and chest wall involvement.

METHODS

The nature of these special clinical cases is such that in most cases, meta-analyses or large prospective studies of patients are not available. To ensure that these guidelines were supported by the most current data available, publications appropriate to the topics covered in this article were obtained by performing a literature search of the MEDLINE computerized database. Where possible, we also reference other consensus opinion statements. Recommendations were developed by the writing committee, graded by a standardized method, and reviewed by all members of the Lung Cancer Guidelines panel prior to approval by the Thoracic Oncology NetWork, Guidelines Oversight Committee, and the Board of Regents of the American College of Chest Physicians.

RESULTS

In patients with a Pancoast tumor, a multimodality approach appears to be optimal, involving chemoradiotherapy and surgical resection, provided that appropriate staging has been carried out. Carefully selected patients with central T4 tumors that do not have mediastinal node involvement are uncommon, but surgical resection appears to be beneficial as part of their treatment rather than definitive chemoradiotherapy alone. Patients with lung cancer and an additional malignant nodule are difficult to categorize, and the current stage classification rules are ambiguous. Such patients should be evaluated by an experienced multidisciplinary team to determine whether the additional lesion represents a second primary lung cancer or an additional tumor nodule corresponding to the dominant cancer. Highly selected patients with a solitary focus of metastatic disease in the brain or adrenal gland appear to benefit from resection or stereotactic radiosurgery. This is particularly true in patients with a long disease-free interval. Finally, in patients with chest wall involvement, provided that the tumor can be completely resected and N2 nodal disease is absent, primary surgical resection should be considered.

CONCLUSIONS

Carefully selected patients with more uncommon presentations of lung cancer may benefit from an aggressive surgical approach.

Clinicopathologic study of serous tubal intraepithelial carcinoma with invasive carcinoma: is serous tubal intraepithelial carcinoma a reliable feature for determining the organ of origin?

In the past several decades, the concept of serous ovarian carcinoma has been revised repeatedly. However, the exact pathogenesis remains controversial. The most popular current concept is origin from the epithelium of the fimbriated ends of the fallopian tubes. The objective of our study was to evaluate the characteristic clinical and morphologic features of serous tubal intraepithelial carcinoma (STIC) and associated invasive carcinomas. One hundred sixteen consecutive cases of STIC seen from 2007 to 2011 were included in this study. High-grade serous carcinoma (HGSC) with or without a mixed component was identified in 107 cases (92.2%), non-HGSC in 5 cases, and STICs without invasive carcinoma in 4 cases. Using conventional criteria, HGSCs were classified as fallopian tube in origin in 65 cases (60.7%), as ovarian in 30 (28.0%), as peritoneal in 9 (8.4%), and as endometrial in 3 (2.8%). Among the 107 cases with HGSCs, most STICs (86; 80%) were present unilaterally, whereas invasive tumors more commonly involved the ovaries bilaterally (79%; 84 cases). These findings support the hypothesis that STIC acts as a precursor lesion for most fallopian tube, ovarian, and peritoneal HGSCs, but not for endometrial HGSC.

Dilemmas in Lung Cancer Staging

The TNM staging system is the most important prognostic factor for lung cancer. The most encountered difficulties in pathologic staging of lung cancer include assessment of pleural invasion, synchronous tumor nodules, and lymph node sampling.

A comparison of Twist and E-cadherin protein expression in primary non-small-cell lung carcinoma and corresponding metastases

OBJECTIVE

The metastasis of solid tumors is directly or indirectly responsible for most cancer-related deaths. It has already been known that in non-small-cell lung carcinoma cells, up-regulation of Twist (a highly conserved basic helix-loop-helix transcription factor) can promote epithelial-mesenchymal transition through down-regulation of E-cadherin. The main aim of this study was to determine whether the expression of Twist and E-cadherin differs between primary and metastatic lung carcinoma and to correlate Twist and E-cadherin expression in primary and metastatic non-small-cell lung carcinoma.

METHODS

Thirteen patients with non-small-cell lung carcinoma and hematogenous metastases were studied in retrospect, and Twist and E-cadherin were detected by immunohistochemistry in 26 tissue samples from the 13 patients.

RESULTS

We demonstrated that the expression of Twist was higher in metastatic non-small-cell lung carcinoma tissues than in primary non-small-cell lung carcinoma (p=0.008) and discordance of Twist expression was observed in 11 (85%) patients. For E-cadherin, 12 cases (92%) showed discordance between primary tumor and metastasis (p=0.002): E-cadherin expressed higher in the primary tumor than in the metastasis in 12 cases. We also found that increased Twist expression was correlated with decreased membranous E-cadherin expression (p=0.009).

CONCLUSIONS

Our data imply that Twist induces epithelial-mesenchymal transition in non-small-cell lung carcinoma by reducing E-cadherin, then promoting metastasis.

International association for the study of lung cancer/american thoracic society/european respiratory society international multidisciplinary classification of lung adenocarcinoma

INTRODUCTION

Adenocarcinoma is the most common histologic type of lung cancer. To address advances in oncology, molecular biology, pathology, radiology, and surgery of lung adenocarcinoma, an international multidisciplinary classification was sponsored by the International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society. This new adenocarcinoma classification is needed to provide uniform terminology and diagnostic criteria, especially for bronchioloalveolar carcinoma (BAC), the overall approach to small nonresection cancer specimens, and for multidisciplinary strategic management of tissue for molecular and immunohistochemical studies.

METHODS

An international core panel of experts representing all three societies was formed with oncologists/pulmonologists, pathologists, radiologists, molecular biologists, and thoracic surgeons. A systematic review was performed under the guidance of the American Thoracic Society Documents Development and Implementation Committee. The search strategy identified 11,368 citations of which 312 articles met specified eligibility criteria and were retrieved for full text review. A series of meetings were held to discuss the development of the new classification, to develop the recommendations, and to write the current document. Recommendations for key questions were graded by strength and quality of the evidence according to the Grades of Recommendation, Assessment, Development, and Evaluation approach.

RESULTS

The classification addresses both resection specimens, and small biopsies and cytology. The terms BAC and mixed subtype adenocarcinoma are no longer used. For resection specimens, new concepts are introduced such as adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) for small solitary adenocarcinomas with either pure lepidic growth (AIS) or predominant lepidic growth with ≤ 5 mm invasion (MIA) to define patients who, if they undergo complete resection, will have 100% or near 100% disease-specific survival, respectively. AIS and MIA are usually nonmucinous but rarely may be mucinous. Invasive adenocarcinomas are classified by predominant pattern after using comprehensive histologic subtyping with lepidic (formerly most mixed subtype tumors with nonmucinous BAC), acinar, papillary, and solid patterns; micropapillary is added as a new histologic subtype. Variants include invasive mucinous adenocarcinoma (formerly mucinous BAC), colloid, fetal, and enteric adenocarcinoma. This classification provides guidance for small biopsies and cytology specimens, as approximately 70% of lung cancers are diagnosed in such samples. Non-small cell lung carcinomas (NSCLCs), in patients with advanced-stage disease, are to be classified into more specific types such as adenocarcinoma or squamous cell carcinoma, whenever possible for several reasons: (1) adenocarcinoma or NSCLC not otherwise specified should be tested for epidermal growth factor receptor (EGFR) mutations as the presence of these mutations is predictive of responsiveness to EGFR tyrosine kinase inhibitors, (2) adenocarcinoma histology is a strong predictor for improved outcome with pemetrexed therapy compared with squamous cell carcinoma, and (3) potential life-threatening hemorrhage may occur in patients with squamous cell carcinoma who receive bevacizumab. If the tumor cannot be classified based on light microscopy alone, special studies such as immunohistochemistry and/or mucin stains should be applied to classify the tumor further. Use of the term NSCLC not otherwise specified should be minimized.

CONCLUSIONS

This new classification strategy is based on a multidisciplinary approach to diagnosis of lung adenocarcinoma that incorporates clinical, molecular, radiologic, and surgical issues, but it is primarily based on histology. This classification is intended to support clinical practice, and research investigation and clinical trials. As EGFR mutation is a validated predictive marker for response and progression-free survival with EGFR tyrosine kinase inhibitors in advanced lung adenocarcinoma, we recommend that patients with advanced adenocarcinomas be tested for EGFR mutation. This has implications for strategic management of tissue, particularly for small biopsies and cytology samples, to maximize high-quality tissue available for molecular studies. Potential impact for tumor, node, and metastasis staging include adjustment of the size T factor according to only the invasive component (1) pathologically in invasive tumors with lepidic areas or (2) radiologically by measuring the solid component of part-solid nodules.

Comparative mutational profiling in the assessment of lung lesions: should it be the standard of care?

BACKGROUND

Discerning primary versus metastatic lung lesions is problematic. Comparative mutational profiling (CMP) involves genetic and point mutation analysis of lesions to facilitate this. We sought to review our experience in cases of two lung lesions or head and neck cancer and lung lesions to determine whether a significantly clinical problem existed, what standard processes were in place to address it, and whether a new diagnostic standard was required.

METHODS

Between January 1, 2007, and October 31, 2008, CMP was used in 24 cases of two lung lesions or a head and neck cancer and lung lesion. Routine hematoxylin and eosin stain examination and immunohistochemistry were performed as appropriate. The CMP involved DNA sequencing for specific oncogene point mutations and a panel of allelic imbalance markers. Metastatic cancer required demonstration of concordant mutations affecting the same allele copy in different cancer deposits.

RESULTS

The patient mean age was 62 years; there were 13 men and 11 women. The cases involved two lung lesions (n = 13) or a head and neck cancer and a lung lesion (n = 11). Standard pathology examination was unable to discriminate the lesions, and they were subsequently differentiated by CMP. Fifteen discordant CMP results were interpreted as independent primaries; 9 cases were concordant, consistent with metastatic disease.

CONCLUSIONS

Discerning primary versus metastatic disease when dealing with lung lesions is a clinically significant problem. Comparative mutational profiling was found to be useful and reliable to assess the relatedness of multiple cancer lesions when routine pathology assessment was unable to.

Testing clonal relatedness of tumors using array comparative genomic hybridization: a statistical challenge

In recent years several investigative groups have sought to use array technologies that characterize somatic alterations in tumors, such as array comparative genomic hybridization (ACGH), to classify pairs of tumors from the same patients as either independent primary cancers or metastases. A wide variety of strategies have been proposed. Several groups have endeavored to use hierarchical clustering for this purpose. This technique was popularized in genomics as a means of finding clusters of patients with similar gene expression patterns with a view to finding subcategories of tumors with distinct clinical characteristics. Unfortunately, this method is not well suited to the problem of classifying individual pairs of tumors as either clonal or independent. In this article we show why hierarchical clustering is unsuitable for this purpose, and why this method has the paradoxical property of producing a declining probability that clonal tumor pairs will be correctly identified as more information is accrued (i.e., more patients). We discuss alternative strategies that have been proposed, which are based on more conventional conceptual formulations for statistical testing and diagnosis, and point to the remaining challenges in constructing valid and robust techniques for this problem.

Genomic and mutational profiling to assess clonal relationships between multiple non-small cell lung cancers

PURPOSE

In cases of multiple non-small cell lung cancer, clinicians must decide whether patients have independent tumors or metastases and tailor treatment accordingly. Decisions are currently made using the Martini and Melamed criteria, which are mostly based on tumor location and histologic type. New genomic tools could improve the ability to assess tumor clonality.

EXPERIMENTAL DESIGN

We obtained fresh-frozen tumors specimens from patients who underwent surgery on at least two occasions for presumptively independent NSCLC. We did array comparative genomic hybridization (aCGH), mutational profiling of select genes, and detailed clinicopathologic review.

RESULTS

We analyzed a total of 42 tumors from 20 patients (6 patients with synchronous tumors, 14 patients with metachronous tumors, 24 potential tumor pair comparisons); 22 tumor pairs were evaluable by aCGH. Surprisingly, classification based on genomic profiling contradicted the clinicopathologic diagnosis in four (18%) of the comparisons, identifying independent primaries in one case diagnosed as metastasis and metastases in three cases diagnosed as independent primaries. Matching somatic point mutations were observed in these latter three cases. Another four tumor pairings were assigned an "equivocal" result based on aCGH; however, matching somatic point mutations were also found in these tumor pairs. None of the tumor pairs deemed independent primaries by aCGH harbored matching mutations.

CONCLUSION

Genomic analysis can help distinguish clonal tumors from independent primaries. The development of rapid, inexpensive, and reliable molecular tools may allow for refinement of clinicopathologic criteria currently used in this setting.

Evidence for common clonal origin of multifocal lung cancers

BACKGROUND

Lung cancer is the most common cause of cancer death in the United States. Multiple anatomically separate but histologically similar lung tumors are often found in the same patient. The clonal origin of multiple lung tumors is uncertain.

METHODS

We analyzed 70 lung tumors from 30 patients (23 females and seven males) who underwent surgical resection for lung epithelial tumors, of whom 26 had non-small cell carcinomas and four had carcinoid/atypical carcinoid tumors. All patients had multiple tumors (two to five) involving one or both lungs. Genomic DNA was extracted from paraffin-embedded tissue sections using laser capture microdissection and analyzed for loss of heterozygosity, TP53 mutations, and X-chromosome inactivation status. The percentage (95% confidence interval [CI]) of patients in whom there were concordant patterns of genetic alteration was calculated.

RESULTS

All 30 case subjects showed loss of heterozygosity (LOH) in at least one and at most four of the six polymorphic microsatellite markers. Completely concordant LOH patterns between synchronous and metachronous cancers in individual patients were seen in 26 (87%) of 30 informative patients (95% CI = 75% to 99%). Identical point mutations were present in eight of 10 patients who exhibited TP53 mutation by sequencing. Tumors in 18 (78%) of 23 female patients (95% CI = 67% to 98%) showed identical X-chromosome inactivation patterns. Combining the results of LOH studies, TP53 mutation screening analyses, and X-chromosome inactivation data, we demonstrated that the multiple separate tumors in 23 (77%) of 30 patients (95% CI = 62% to 92%) had identical genetic changes, consistent with monoclonal origin of the separate tumors.

CONCLUSIONS

Our data indicate that the great majority of multifocal lung cancers have a common clonal origin and that multifocality in lung cancer represents local and regional intrapulmonary metastasis.

Evaluation of the clonal origin of multiple primary melanomas using molecular profiling

Numerous investigations have been conducted using molecular profiling to evaluate the possible clonal origin of second malignancies in various cancer types. However, to date no study assessing clonality of multiple primaries has been conducted in melanoma. In this investigation using patients treated at a specialist melanoma treatment center, we compared the somatic mutational profiles of pairs of melanomas designated as independent on the basis of thorough assessment of their clinical and pathologic characteristics. We used a set of highly polymorphic genetic markers selected on the basis of their chromosomal positions and the frequencies of reported allelic losses at these genetic loci. Our statistical testing strategy showed no significant evidence of clonal origin of the two primaries in 17 of the 19 patients examined. The results suggest that most second melanomas designated as independent primary tumors on the basis of their clinicopathologic features are indeed independent occurrences of the disease, supporting the validity of the criteria used by experienced pathologists in distinguishing new primaries from metastases.

Combined small cell lung carcinomas: genotypic and immunophenotypic analysis of the separate morphologic components

Combined small cell lung carcinomas (CSCLCs) are small cell lung carcinomas (SCLCs) containing discrete areas of non-small cell morphologic components, found in up to 30% of SCLCs. We assessed immunophenotypic and genotypic similarity between the distinct morphologic constituents in 7 CSCLCs. Each was stained for synaptophysin, CD56, chromogranin, bcl-2, thyroid transcription factor (TTF)-1, cytokeratin 7, and PAX-5. Loss of heterozygosity (LOH) analysis was performed using markers on 3p (2 loci), 17p (3 loci), 17q (1 locus), and 22q (2 loci). The distinct components shared an identical immunophenotype in 6 cases; all were positive for synaptophysin and CD56 in both components. LOH analysis revealed shared loss of least 1 marker in every lesion, including LOH at 22q13 (characteristic of SCLC) in 5 tumors. The individual elements constituting CSCLCs are closely related in most cases despite their distinct morphologic appearances. The prevalent expression of synaptophysin and CD56 and loss of 22q13 suggest that these tumors are biologically closer to SCLC.

Liver transplantation for hepatocellular carcinoma: extension of indications based on molecular markers

BACKGROUND/AIMS

Liver transplantation usually cures hepatocellular carcinoma when the Milan selection criteria are applied, whereas there is substantial risk of posttransplant recurrence with tumors beyond these criteria. This study uses molecular data to identify a subgroup of patients who, despite having hepatocellular carcinoma beyond Milan criteria, have favorable outcomes.

METHODS

Allelic imbalance of 18 microsatellites was analyzed in 70 consecutive patients (35 within Milan, 35 beyond Milan criteria) transplanted for hepatocellular carcinoma of whom 24 had recurrence and 46 survived at least 5 years recurrence-free. Fractional allelic imbalance (the fraction of significant microsatellites that demonstrated allelic imbalance) and relevant clinical/pathological variables were tested for correlation with time to recurrence.

RESULTS

Allelic imbalance in 9/18 microsatellites correlated with recurrence. Fractional allelic imbalance > 0.27 and macrovascular invasion were independent predictors of recurrence in patients with tumors beyond Milan criteria; the probability of recurrence at 5 years was 85% with fractional allelic imbalance > or = 0.27 vs. 10% when < 0.27 (p=0.0002). An algorithm including Milan criteria and fractional allelic imbalance status is 89% accurate in predicting tumor recurrence after transplantation.

CONCLUSION

Analysis of allelic imbalance of 9 microsatellites identifies a subgroup of patients who, despite having hepatocellular carcinoma beyond Milan criteria, have a low risk of posttransplant recurrence.

EGFR assays in lung cancer

The development of small-molecule inhibitors of the epidermal growth factor receptor (EGFR) resulted in new therapeutic options for patients with advanced lung cancer. It was clear from the experience with targeted therapy for breast cancer that a new standardized assay procedure for assessing and predicting the effects of therapeutic agents must be developed. Three academic groups almost simultaneously reported the discovery of somatic mutations in the exons 18 to 21 of the tyrosine kinase (TK) domain of EGFR that correlated with a high likelihood of response to EGFR TK inhibitors. This observation revolutionized understanding of EGFR in lung carcinogenesis and resulted in numerous retrospective studies that correlated patient's response and molecular profile of the lung adenocarcinoma. The results of these studies indicate that clinical benefits from treatment with EGFR TK inhibitors are variable between the different subsets of patients. Multiple methodologic approaches were used including mutational analysis, fluorescence in situ hybridization, and immunohistochemistry. Conflicting results reflect the lack of standardization of the methodology and interpretation. Sample types, sample processing, and storage should also be taken into consideration as another potentially confounding factor. Therefore, it is important to standardize the approach and decide which assays are best to predict patient response to targeted therapies. It is also essential to determine the most cost-effective way to integrate EGFR molecular assays into clinical practice. This review will address practical aspects of each of the currently proposed assays. Difficulties in standardization of these assays in a clinical practice will be discussed.

Restoration of fragile histidine triad expression restores Chk2 activity in response to ionizing radiation in oral squamous cell carcinoma cells

Early in tumorigenesis, a DNA damage-response network is activated in preneoplastic cells that delays or prevents cancer. Activation of the Chk2 G(2)/M checkpoint kinase and loss of fragile histidine triad (Fhit) tumor suppressor expression increase cellular susceptibility to DNA-damaging 'oncogenic' stressors, particularly in precursor or precancerous lesions. To understand the mechanism of oral carcinogenesis, we assessed the association between phosphorylated Chk2 (pChk2) and Fhit expression in oral squamous cell carcinoma. Loss of Fhit expression was an early event during oral carcinogenesis, whereas a decrease in the number of pChk2-positive cells was associated with tumor progression. Although tyrosine 114 is known to be essential to Fhit's tumor-suppressing activity, both wild-type and tyrosine 114 mutant Fhit increased the population of subG(1) DNA-containing HSC-3 OSCC cells with elevated pChk2 levels. In particular, when cells were exposed to ionizing radiation, pChk2 levels were upregulated dramatically, as were those of its downstream target Cdc25C. Knockdown of Fhit with FHIT small interfering RNA diminished the ionizing radiation-induced Chk2 phosphorylation in HEK293 cells. Furthermore, Fhit-deficient mice demonstrated a decrease in the number of pChk2-positive cells not only in dysplastic lesions but also in N-nitrosobenzylamine-induced papilloma of the forestomach, suggesting that lack of Fhit expression and the resultant defects of the ataxia telangiectasia mutated-Chk2 pathway can cause a difference in the incidence of N-nitrosobenzylamine-induced forestomach lesions. These findings suggest that Fhit plays a key role in the regulation of the ataxia telangiectasia mutated-Chk2 DNA damage response during oral carcinogenesis.

Breast-cancer stromal cells with TP53 mutations and nodal metastases

BACKGROUND

The importance of cross-talk between a cancer and its microenvironment has been increasingly recognized. We hypothesized that mutational inactivation of the tumor-suppressor gene TP53 and genomic alterations in stromal cells of a tumor's microenvironment contribute to the clinical outcome.

METHODS

We performed TP53 mutation analysis and genomewide analysis of loss of heterozygosity and allelic imbalance on DNA from isolated neoplastic epithelial and stromal cells from 43 patients with hereditary breast cancer and 175 patients with sporadic breast cancer. Compartment-specific patterns and TP53 mutations were analyzed. Associations between compartment-specific TP53 status, loss of heterozygosity or allelic imbalance, and clinical and pathological characteristics were computed.

RESULTS

TP53 mutations were associated with an increased loss of heterozygosity and allelic imbalance in both hereditary and sporadic breast cancers, but samples from patients with hereditary disease had more frequent mutations than did those from patients with sporadic tumors (74.4% vs. 42.3%, P=0.001). Only 1 microsatellite locus (2p25.1) in stromal cells from hereditary breast cancers was associated with mutated TP53, whereas there were 66 such loci in cells from sporadic breast cancers. Somatic TP53 mutations in stroma, but not epithelium, of sporadic breast cancers were associated with regional nodal metastases (P=0.003). A specific set of five loci linked to an increased loss of heterozygosity and allelic imbalance in the stroma of sporadic tumors was associated with nodal metastases in the absence of TP53 mutations. No associations were found between any of the clinical or pathological features of hereditary breast cancer with somatic TP53 mutations.

CONCLUSIONS

Stroma-specific loss of heterozygosity or allelic imbalance is associated with somatic TP53 mutations and regional lymph-node metastases in sporadic breast cancer but not in hereditary breast cancer.

Commonly encountered difficulties in pathologic staging of lung cancer

CONTEXT

Lung cancer is the leading cause of cancer mortality worldwide. Despite technological, therapeutic, and scientific advances, most patients present with incurable disease and a poor chance of long-term survival. For those with potentially curable disease, lung cancer staging greatly influences therapeutic decisions. Therefore, surgical pathologists determine many facets of lung cancer patient care.

OBJECTIVE

To present the current lung cancer staging system and examine the importance of mediastinal lymph node sampling, and also to discuss particularly confusing and/or challenging areas in lung cancer staging, including assessment of visceral pleura invasion, bronchial and carinal involvement, and the staging of synchronous carcinomas.

DATA SOURCES

Published current and prior staging manuals from the American Joint Committee on Cancer and the International Union Against Cancer as well as selected articles pertaining to lung cancer staging and diagnosis accessible through PubMed (National Library of Medicine) form the basis of this review.

CONCLUSIONS

Proper lung cancer staging requires more than a superficial appreciation of the staging system. Clinically relevant specimen gross examination and histologic review depend on a thorough understanding of the staging guidelines. Common sense is also required when one is confronted with a tumor specimen that defies easy assignment to the TNM staging system.

Overexpression of Dicer in precursor lesions of lung adenocarcinoma

Differential microRNA (miR) expression is described in non-small cell lung carcinoma. miR biogenesis requires a set of proteins collectively referred to as the miR machinery. In the proposed multistep carcinogenesis model, peripheral adenocarcinoma of the lung develops from noninvasive precursor lesions known as atypical adenomatous hyperplasia (AAH) and bronchioloalveolar carcinoma (BAC). The gene array analysis of BAC and adenocarcinoma showed a transient up-regulation of Dicer (a key effector protein for small interfering RNA and miR function) and PACT along with down-regulation of most genes encoding miR machinery proteins. Immunohistochemically, Dicer was up-regulated in AAH and BAC and down-regulated in areas of invasion and in advanced adenocarcinoma. A fraction of adenocarcinomas lose Dicer as a result of deletions at the Dicer locus. Expanded immunohistochemical and Western blot analysis showed higher Dicer level in squamous cell carcinoma (SCC) of the lung when compared with adenocarcinoma. Other proteins of the RNA-induced silencing complex (RISC; SND1, PACT, and FXR1) were also present at higher levels in a SCC cell line when compared with an adenocarcinoma cell line. In conclusion, the stoichiometry of miR machinery and RISC depends on histologic subtype of lung carcinoma, varies along the AAH-BAC-adenocarcinoma sequence, and might explain the observed abnormal miR profile in lung cancer. The status of the endogenous miR machinery in various histologic subtypes and stages of lung cancer may help to predict the toxicity of and susceptibility to future RNA interference-based therapy.

Capillary electrophoresis and the clinical laboratory

Over the past 15 years, CE as an analytical tool has shown great promise in replacing many conventional clinical laboratory methods, such as electrophoresis and HPLC. CE's appeal was that it was fast, used very small amounts of sample and reagents, was extremely versatile, and was able to separate large and small analytes, whether neutral or charged. Because of this versatility, numerous methods have been developed for analytes that are of clinical interest. Other than molecular diagnostic and forensic laboratories CE has not been able to make a major impact in the United States. In contrast, in Europe and Japan an increasing number of clinical laboratories are using CE. Now that automated multicapillary instruments are commercially available along with cost-effective test kits, CE may yet be accepted as an instrument that will be routinely used in the clinical laboratories. This review will focus on areas where CE has the potential to have the greatest impact on the clinical laboratory. These include analyses of proteins found in serum and urine, hemoglobin (A1c and variants), carbohydrate-deficient transferrin, forensic and therapeutic drug screening, and molecular diagnostics.

Synchronous multiple primary lung cancers with different response to gefitinib

Synchronous bronchiolo-alveolar cell carcinoma (BAC) in both lungs and squamous cell carcinoma in left lung were found in a 66-year-old male smoker. After two courses of chemotherapy with gemcitabine and carboplatin, the left lung mass had partially resolved, however, the extent of BAC had been increased. When gefitinib was used as a second-line chemotherapy, the consolidation lesions of BAC was improved while the mass of squamous cell carcinoma was aggravated. The analysis of epidermal growth factor receptor-tyrosine kinase (EGFR-TK) mutations showed that BAC had the deletion, delE746-A750 in exon 19, however, squamous cell carcinoma had no mutations. These synchronous tumors with different location, histology, status of EGFR-TK mutations and response to chemotherapy might be caused by different molecular pathogenesis.

Total-genome analysis of BRCA1/2-related invasive carcinomas of the breast identifies tumor stroma as potential landscaper for neoplastic initiation

We have shown that the tumor microenvironment of sporadic breast cancer is diverse in genetic alterations and contributes to the cancer phenotype. The dynamic morphology of the mammary gland might be of special interest in hereditary breast/ovarian cancer syndrome (HBOC). We hypothesized that hotspots of loss of heterozygosity or allelic imbalance (LOH/AI) within the tumor stroma of BRCA1/2-related breast cancers provide an impaired mammary stroma that could facilitate later malignant transformation of the breast epithelium. We conducted a total genome LOH/AI scan of DNA derived from the epithelium and stroma of 51 BRCA1/2-related breast cancers, using 372 microsatellite markers. We compared these data with those from a set of 134 sporadic breast cancers. HBOC-related breast cancers accumulated significantly more genetic alterations than did sporadic breast cancers. BRCA1/2-related breast cancer stroma showed LOH/AI at 59.7% of all loci analyzed, similar to the average frequency of LOH/AI observed in the epithelium (66.2%). This is remarkably different from sporadic breast cancers, for which the average epithelial LOH/AI frequency (36.7%) far exceeds the average stromal LOH/AI frequency (28.4%) (P=.03). We identified 11 hotspot loci of LOH/AI in the BRCA1/2 stroma, encompassing genes such as POLD1, which functions in DNA replication, and SDHB. In a subset of samples, enriched for BRCA1 cases, we found 45.0% overall LOH/AI in the stroma, which was significantly higher than the 41.8% LOH/AI observed in corresponding epithelium (P=.04). Together, our data indicate that, in HBOC-related breast cancers, the accumulation of genomic instability in the cancer stroma coincides with that in the neoplastic epithelium, and we postulate that such a genetically unstable stroma might facilitate a microenvironment that functions as a landscaper that promotes genomic instability in the epithelium and, subsequently, neoplastic transformation.