Mutations of the P53 tumor suppressor gene as clonal marker for multiple primary 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.

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.

Genetic trajectory and clonal evolution of multiple primary lung cancer with lymph node metastasis

Multiple primary lung cancer (MPLC) with lymph node metastasis (LNM) is a rare phenomenon of multifocal lung cancer. The genomic landscapes of MPLC and the clonal evolution pattern between primary lung lesions and lymph node metastasis haven't been fully illustrated. We performed whole-exome sequencing (WES) on 52 FFPE (Formalin-fixed Paraffin-Embedded) samples from 11 patients diagnosed with MPLC with LNM. Genomic profiling and phylogenetic analysis were conducted to infer the evolutional trajectory within each patient. The top 5 most frequently mutated genes in our study were TTN (76.74%), MUC16 (62.79%), MUC19 (55.81%), FRG1 (46.51%), and NBPF20 (46.51%). For most patients in our study, a substantial of genetic alterations were mutually exclusive among the multiple pulmonary tumors of the same patient, suggesting their heterogenous origins. Individually, the genetic profile of lymph node metastatic lesions overlapped with that of multiple lung cancers in different degrees but are more genetically related to specific pulmonary lesions. SETD2 was a potential metastasis biomarker of MPLC. The mean putative neo-antigen number of the primary tumor (646.5) is higher than that of lymph node metastases (300, p = 0.2416). Primary lung tumors and lymph node metastases are highly heterogenous in immune repertoires. Our findings portrayed the comprehensive genomic landscape of MPLC with LNM. We characterized the genomic heterogeneity among different tumors. We offered novel clues to the clonal evolution between MPLC and their lymphatic metastases, thus advancing the treatment strategies and preventions of MPLC with LNM.

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.

The Role of Whole Exome Sequencing in Distinguishing Primary and Secondary Lung Cancers

Non-small cell lung cancer (NSCLC) that presents with multiple lung tumors (MLTs) poses a challenge to accurate staging and prognosis. MLTs that arise as clonally related secondary metastases from a common primary are higher stage and often require adjuvant chemotherapy or may in fact be incurable stage IV lesions. Conversely, MLTs that represent distinct primaries have a better prognosis and may be overtreated if inappropriately classified as related secondaries. Historically, pathologic and radiographic criteria were used to distinguish between primary and secondary MLTs; however, the advent of genomic profiling has demonstrated limitations to these historic classification systems. In this review, we discuss the use of molecular profiling to distinguish between primary and secondary lung cancers, with a focus on the insights gleaned from whole exome sequencing (WES) analyses. While WES is not yet feasible in routine clinical practice, WES studies have helped elucidate the clonal relationship between primary and secondary lung cancers and provide important context for the application of targeted sequencing panel-based analyses.

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.

Comprehensive Next-Generation Sequencing Unambiguously Distinguishes Separate Primary Lung Carcinomas From Intrapulmonary Metastases: Comparison with Standard Histopathologic Approach

PURPOSE

In patients with >1 non-small cell lung carcinoma (NSCLC), the distinction between separate primary lung carcinomas (SPLCs) and intrapulmonary metastases (IPMs) is a common diagnostic dilemma with critical staging implications. Here, we compared the performance of comprehensive next-generation sequencing (NGS) with standard histopathologic approaches for distinguishing NSCLC clonal relationships in clinical practice.

EXPERIMENTAL DESIGN

We queried 4,119 NSCLCs analyzed by 341-468 gene MSK-IMPACT NGS assay for patients with >1 surgically resected tumor profiled by NGS. Tumor relatedness predicted by prospective histopathologic assessment was contrasted with comparative genomic profiling by subsequent NGS.

RESULTS

Sixty patients with NGS performed on >1 NSCLCs were identified, yielding 76 tumor pairs. NGS classified tumor pairs into 51 definite SPLCs (median, 14; up to 72 unique somatic mutations per pair), and 25 IPMs (24 definite, one high probability; median, 5; up to 16 shared somatic mutations per pair). Prospective histologic prediction was discordant with NGS in 17 cases (22%), particularly in the prediction of IPMs (44% discordant). Retrospective review highlighted several histologic challenges, including morphologic progression in some IPMs. We subsampled MSK-IMPACT data to model the performance of less comprehensive assays, and identified several clinicopathologic differences between NGS-defined tumor pairs, including increased risk of subsequent recurrence for IPMs.

CONCLUSIONS

Comprehensive NGS allows unambiguous delineation of clonal relationship among NSCLCs. In comparison, standard histopathologic approach is adequate in most cases, but has notable limitations in the recognition of IPMs. Our results support the adoption of broad panel NGS to supplement histology for robust discrimination of NSCLC clonal relationships in clinical practice.

Multiple primary lung cancer: a rising challenge

With the use of high-resolution chest imaging system and lung cancer screening program, patients with multiple primary lung cancers (MPLCs) are becoming a growing population in clinical practice worldwide. The diagnostic criteria for MPLCs has been established and modified by three major lung cancer research institutes. However, due to the fact that the differential diagnosis between MPLCs and a recurrence, metastatic, or satellite lesion arising from the original lesion remains ambiguous and confusing, there is still insufficient evidence to support a uniform guideline. Newly developed molecular and genomic methods have the potential to better define the relationship among multiple lesions and bring the possibility of targeted therapy. Surgical resection remains the first choice for the treatment of MPLCs and detailed strategy should be carefully planned taking characteristics of the tumor and status of patients into consideration. For those who are intolerant to surgery, a new technology called stereotactic body radiation therapy (SBRT) is now an optional therapeutic strategy. Furthermore, multiple GGOs are unique MPLCs that need special attentions in the clinical practice.

Effect of cyclical intermittent hypoxia on Ad5CMVCre induced solitary lung cancer progression and spontaneous metastases in the KrasG12D+; p53fl/fl; myristolated p110fl/fl ROSA-gfp mouse

BACKGROUND

Epidemiological data suggests that obstructive sleep apnea (OSA) is associated with increased cancer incidence and mortality. We investigate the effects of cyclical intermittent hypoxia (CIH), akin to the underlying pathophysiology of OSA, on lung cancer progression and metastatic profile in a mouse model.

METHODS

Intrathoracic injection of Ad5CMVCre virus into a genetically engineered mouse (GEM) KrasG12D+/-; p53fl/fl; myristolated-p110αfl/fl-ROSA-gfp was utilized to induce a solitary lung cancer. Male mice were then exposed to either CIH or Sham for 40-41 days until harvest. To monitor malignant progression, serial micro CT scans with respiratory gating (no contrast) was performed. To detect spontaneous metastases in distant organs, H&E and immunohistochemistry were performed.

RESULTS

Eighty-eight percent of injected Ad5CMVCre virus was recovered from left lung tissue, indicating reliable and accurate injections. Serial micro CT demonstrated that CIH increases primary lung tumor volume progression compared to Sham on days 33 (p = 0.004) and 40 (p<0.001) post-injection. In addition, CIH increases variability in tumor volume on day 19 (p<0.0001), day 26 (p<0.0001), day 33 (p = 0.025) and day 40 (p = 0.004). Finally, metastases are frequently detected in heart, mediastinal lymph nodes, and right lung using H&E and immunohistochemistry.

CONCLUSIONS

Using a GEM mouse model of metastatic lung cancer, we report that male mice with solitary lung cancer have accelerated malignant progression and increased variability in tumor growth when exposed to cyclical intermittent hypoxia. Our results indicate that cyclical intermittent hypoxia is a pathogenic factor in non-small cell lung cancer that promotes the more rapid growth of developing tumors.

Comparative mutational evaluation of multiple lung cancers by multiplex oncogene mutation analysis

In patients presenting with synchronous or metachronous multiple lung cancer (MLC), it is important to distinguish between multiple primary lung cancer (MP) and intrapulmonary metastasis (IM). The present study was aimed at investigating the mutational profiles of synchronous/metachronous MLC and to compare the classification of paired tumors by multiplex gene mutation analysis with the histopathological evaluation. We carried out targeted sequencing of 20 lung cancer-related oncogenes using next-generation sequencing (NGS) in 82 tumors from 37 MLC patients who underwent surgical resection at our department. The patients were diagnosed as MP or IM cases based on the Martini and Melamed criteria, histopathological and gene mutational evaluations. Matching mutations between paired tumors was observed in 20 (54%) patients, who were diagnosed as IM cases by mutational evaluation. Patients who could not be clearly diagnosed by histopathological evaluation were classified as equivocal cases. Among the histopathological IM cases (n = 7), six (86%) were confirmed as IM cases also by mutational evaluation, and most of the paired tumors of these cases (n = 5) harbored multiple matching mutations. Among the histopathological MP cases (n = 17), mutational evaluation yielded a discordant diagnosis in eight (47%) cases. Of these, the paired tumors of four cases harbored multiple matching mutations, suggesting that the mutational diagnosis might be more suitable in these patients. Our findings suggest that multiplex mutational analysis could be a useful complementary tool for distinguishing between MP and IM in addition to histopathological evaluation.

Mutational analysis of multiple lung cancers: Discrimination between primary and metastatic lung cancers by genomic profile

In cases of multiple lung cancers, individual tumors may represent either a primary lung cancer or both primary and metastatic lung cancers. Treatment selection varies depending on such features, and this discrimination is critically important in predicting prognosis. The present study was undertaken to determine the efficacy and validity of mutation analysis as a means of determining whether multiple lung cancers are primary or metastatic in nature. The study involved 12 patients who underwent surgery in our department for multiple lung cancers between July 2014 and March 2016. Tumor cells were collected from formalin-fixed paraffin-embedded tissues of the primary lesions by using laser capture microdissection, and targeted sequencing of 53 lung cancer-related genes was performed. In surgically treated patients with multiple lung cancers, the driver mutation profile differed among the individual tumors. Meanwhile, in a case of a solitary lung tumor that appeared after surgery for double primary lung cancers, gene mutation analysis using a bronchoscopic biopsy sample revealed a gene mutation profile consistent with the surgically resected specimen, thus demonstrating that the tumor in this case was metastatic. In cases of multiple lung cancers, the comparison of driver mutation profiles clarifies the clonal origin of the tumors and enables discrimination between primary and metastatic tumors.

Does Lymph Node Metastasis Have a Negative Prognostic Impact in Patients with NSCLC and M1a Disease?

OBJECTIVES

Patients with NSCLC with M1a disease regardless of lymph node status were categorized as stage IV. This study aims to investigate whether the N descriptors in M1a patients could provide clinical information.

METHODS

Overall, 39,731 patients with NSCLC with M1a disease were identified from the Surveillance, Epidemiology, and End Results database during 2005-2012. Lung cancer-specific survival (LCSS) was compared among M1a patients stratified by N stage. A Cox proportional hazards regression model was applied to evaluate the prognostic factors. Statistical analyses were performed in all subgroups.

RESULTS

M1a patients without lymph node involvement had the best LCSS, followed by patients with N1 disease; no difference in LCSS was observed between N2 and N3 disease (N0 versus N1, p < 0.001; N1 versus N2, p < 0.001; and N2 versus N3, p = 0.478). Similarly, this trend was observed when patients were subdivided into two temporal cohorts (2005-2008 and 2009-2012) and also when M1a disease was subdivided into contralateral pulmonary nodules and pleural dissemination (malignant pleural effusion [or pericardial effusion] and pleural nodules). In addition, a difference in LCSS between N2 and N3 disease was observed in patients with malignant pleural nodules (p = 0.003). Multivariate analysis showed that lymph node involvement was an independent prognostic factor for M1a patients, and this result was also noticed in all subgroups.

CONCLUSIONS

These results provide preliminary evidence that lymph node stage may have clinical significance among patients with NSCLC with M1a disease, adding prognostic information.

Pathologists' staging of multiple foci of lung cancer: poor concordance in absence of dramatic histologic or molecular differences

OBJECTIVES

A long-standing problem in lung cancer pathology has been to determine whether two anatomically distinct foci of lung carcinoma are independent primaries or intrapulmonary metastases. While several proposals exist with respect to this problem, it is not known how pathologists use these proposals in actual practice.

METHODS

We performed a voluntary survey of the Pulmonary Pathology Society, a self-selected group of pathologists with a specialty interest in pulmonary pathology, to determine their opinion on staging various specific scenarios of multiple foci of lung cancer.

RESULTS

We found that there was a great deal of disagreement and uncertainty in the approach to these scenarios unless there were also unambiguous molecular markers or a dramatic difference in histology.

CONCLUSIONS

Pathologists have a high degree of uncertainty and disagreement on staging multiple lung carcinomas. An improved pathologic method is required to distinguish separate primary tumors from intrapulmonary metastases. Until that is available, improved nomenclature is needed to convey the intrinsic uncertainty of the situation.

Aerogenous metastases: a potential game changer in the diagnosis and management of primary lung adenocarcinoma

OBJECTIVE

The purposes of this article are to summarize the relevant literature on aerogenous metastasis, explain the putative pathogenetic mechanism of aerogenous spread, present the characteristic imaging and pathologic features, and review the importance of aerogenous spread to staging and clinical management.

CONCLUSION

Cumulative evidence suggests that aerogenous spread may exist and is underrecognized. Imaging features are helpful in differentiating possible aerogenous spread of tumor from hematogenous and lymphatic metastases and from synchronous primary tumors. The putative occurrence of intrapulmonary aerogenous metastasis of lung cancer has staging, management, and prognostic implications.

"Different trend" in multiple primary lung cancer and intrapulmonary metastasis

Background

The distinguishing of intrapulmonary metastatic tumors from multiple primary lung cancers is difficult but of great importance for the therapeutic management and prognosis of these patients.

Methods

We used genomic DNA analyzed by six microsatellites (D7S1824, D15S822, D2S1363, D10S1239, D6S1056, and D22S689) with PCR to identify discordant allelic variation from 12 patients. There are five patients with multiple primary lung cancers and seven patients who were diagnosed with intrapulmonary metastases from 850 patients with primary lung cancer in our hospital. The experiments were approved by the West China Hospital Ethics committee (No. 2013 (33)) and all patients agreed to participate in the study and signed an informed consent form.

Results

In the group of metachronous lung tumor, three of five patients have different histological types and one of five patients have the same histological type which showed “contradictory trend”. The other one showed “unique trend”. In the second group (intrapulmonary metastasis lung tumor), one patient showed “contradictory trend” and the others showed “unique trend”.

Conclusions

“Different trends” are useful in discrimination of intrapulmonary metastasis lung cancer and multiple primary lung cancer even diagnosed with the histopathological evaluation.

A novel differential diagnostic model for multiple primary lung cancer: Differentially-expressed gene analysis of multiple primary lung cancer and intrapulmonary metastasis

The incidence of synchronous multiple primary lung cancer (MPLC) is increasing. However, present diagnostic methods are unable to satisfy the individualized treatment requirements of patients with MPLC. The present study aimed to establish a quantitative mathematical model and analyze its diagnostic value for distinguishing between MPLC and cases of the histologically similar disease, intrapulmonary metastasis (IPM). The sum value of the differential expression ratios of four proteins, namely p53, p16, p27 and c-erbB2, was evaluated by immunohistochemically-staining specimens of primary cancers, second separate cancers, metastatic lymph nodes and metastatic cancers. The sum value of the differential expression ratio of the four proteins from the primary tumor and the lymph-node metastasis or metastatic cancer was <90 in the 11 patients with a single metastatic cancer and in the 30 patients with lymph-node metastasis, but was >90 in the 14 patients with different histological types of MPLC. Therefore, a quantitative differentially-expressed gene mathematical model was established as follows: Sum of the differential expression ratios = p16T1 - T + p27T1 - T2 + C-erbB2T1 - T2 + p53T1 - T2, where T1 is the primary cancer and T2 is the lymph node metastasis, metastatic cancer or the second separate cancer. The quantitative differentially-expressed gene mathematical model is considered to be a useful tool for distinguishing between MPLC and IPM.

Clinical features of multiple lung cancers based on thin-section computed tomography: what are the appropriate surgical strategies for second lung cancers?

PURPOSE

We investigated the proper surgical strategies for second lung cancers based on the findings of thin-section CT.

METHODS

We classified 59 patients with second lung cancers into two categories based on the thin-section CT findings. In the ground glass nodule (GGN) group (n = 29), the first and/or the second lung cancers showed a GGN on thin-section CT. In the Solid group (n = 30), both the first and second lung cancers showed a solid appearance.

RESULTS

The overall 5-year survival rate after second surgery was 71.7 %. The univariate analyses revealed that the presence of more than three lung tumors was significantly more common in the GGN group. Regarding the surgical strategies, all the patients in the GGN group underwent limited resection for at least one of the operations, whereas 36 % of those in the Solid group underwent bilateral lobectomy. The 5-year survival in the GGN group (89.1 %) was significantly better than that in the Solid group (40.8 %) (p = 0.0305).

CONCLUSIONS

Limited resection should be performed for GGN patients as much as possible to preserve lung function, due to the possible presence of more than three lung cancers. Despite the higher likelihood of having more tumors, the GGN patients had a better survival. In contrast, lobectomy for second lesions should be aggressively considered for solid tumor patients whenever possible.

Clinicopathology and genetic profile of synchronous multiple small adenocarcinomas: implication for surgical treatment of an uncommon lung malignancy

PURPOSE

Synchronous multiple small adenocarcinomas are detected more frequently than in the past; however, the genetic profile, treatment, and prognosis of patients remain unclear. For treatment decisions and prognostic applications, we evaluated epidermal growth factor receptor (EGFR), p53, and KRAS somatic mutations in synchronous multiple small lung adenocarcinomas.

METHODS

The presence of EGFR, p53, and KRAS somatic mutations was determined in 64 synchronous multiple lung adenocarcinomas ≤2 cm in maximal dimension. Mutational analysis was performed on DNA extracted from paraffin-embedded tumors.

RESULTS

Five-year disease-free survival (DFS) was 86.1 %, and overall survival was 95.8 %. EGFR, p53, and KRAS mutations were detected in 41 (64.1 %), 8 (12.5 %), and 4 (6.3 %) patients, respectively. The high frequency of genetic mutations resulted in a high discrimination rate of tumor clonality (68.8 %; 44/64) in the study group. Fourteen (31.8 %) patients were assessed as having the same clonality, whereas 30 (68.2 %) patients had different clonality, which further supported the concept of field cancerization. Multivariate analysis showed lymph node metastasis (p = 0.003) and smoking (p = 0.011) were significantly correlated with tumor relapse. Surgical method, clonality, and tumor location were not correlated with tumor relapse.

CONCLUSIONS

Whether these tumors are different or the same clonal, sublobar resection of each lesion can achieve long-term DFS and is the treatment of choice for synchronous multiple small lung adenocarcinomas. Patients with lymph node metastasis are at risk of relapse and adjuvant chemotherapy is indicated.

Interaction of cigarette exposure and airway epithelial cell gene expression

Cigarette smoking is responsible for lung cancer and chronic obstructive pulmonary disease (COPD), the leading cause of death from cancer and the second-leading cause of death in the United States. In the United States, 46 million people smoke, with an equal number of former smokers. Moreover, 20-25% of current or former smokers will develop either disease, and smokers with one disease are at increased risk for developing the other. There are no tools for predicting risk of developing either disease; no accepted tools for early diagnosis of potentially curable lung cancer; and no tools for defining molecular pathways or molecular subtypes of these diseases, for predicting rate of progression, or for assessing response to therapy at a biochemical or molecular level. This review discusses current studies and the future potential of measuring global gene expression in epithelial cells that are in the airway field of injury and of using the genomic information derived to begin to answer some of the above questions.

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.

The field of tissue injury in the lung and airway

The concept of field cancerization was first introduced over 6 decades ago in the setting of oral cancer. Later, field cancerization involving histologic and molecular changes of neoplasms and adjacent tissue began to be characterized in smokers with or without lung cancer. Investigators also described a diffuse, nonneoplastic field of molecular injury throughout the respiratory tract that is attributable to cigarette smoking and susceptibility to smoking-induced lung disease. The potential molecular origins of field cancerization and the field of injury following cigarette smoke exposure in lung and airway epithelia are critical to understanding their potential impact on clinical diagnostics and therapeutics for smoking-induced lung disease.

A second-generation profiling system for quantitative methylation analysis of multiple gene promoters: application to lung cancer

Cancer-specific gene promoter methylation has been described in many types of cancers, and various semi-quantified results have shown their usefulness. Here, we show a more sensitive and specific second-generation system for profiling the DNA methylation status. This method is based on bisulfite reaction of DNA and real-time PCR using two TaqMan MGB probes labeled with different fluorescence, followed by clustering analysis. Primers were designed with CpG-less sequences, and TaqMan MGB probes were designed to contain three or four CpG sites and to be shorter than conventional TaqMan probes. We have added new criteria for primer and probe design for further specificity. We confirmed the reliability of this system and applied it to analysis of lung cancers. Using 10 promoters, 90 primary lung cancers were clustered into six groups consisting of cases having similar smoking status and pathological findings. EGFR mutation and p16 promoter DNA methylation were exclusive, as previously reported; however, DNA methylation in other genes was unrelated to EGFR mutation. This system was also useful to distinguish double primary lung cancers from a single cancer with intrapulmonary metastasis. As above, our system has widespread availability in clinical use and biological research.

Clonality and prognostic implications of p53 and epidermal growth factor receptor somatic aberrations in multiple primary lung cancers

PURPOSE

For treatment decision and prognostic applications, we evaluated p53/epidermal growth factor receptor (EGFR) somatic aberrations in multiple primary lung cancers to differentiate multifocal tumors from intrapulmonary metastasis.

EXPERIMENTAL DESIGN

Fifty-eight multiple primary lung cancers of 1,037 patients in a 10-year period were identified to investigate somatic mutations and altered expression of p53 and EGFR for clonality assessment. Genomic DNA was extracted from microdissected cells of paraffin-embedded multiple primary lung cancer tissues. Overexpression and somatic mutations in exons of p53 (exons 5-8) and tyrosine kinase domain of EGFR (exons 18-22) were examined by immunohistochemical staining and DNA sequencing, respectively.

RESULTS

High frequency of somatic mutations in p53 (33 of 58, 56.9%) and/or EGFR (44 of 58, 75.9%) resulted in high discrimination rate of tumor clonality (50 of 58, 86.2%) of multiple primary lung cancers. Twenty-two cases (37.9%) were assessed as having the same clonality and 28 cases (48.3%) were determined as having different clonality, which further supported the carcinogenic theory of field cancerization. Notably, the occurrence of lymph node metastasis was more commonly observed in tumors with the same clonality (P = 0.045) and was associated with poor patient 5-year survival rate (P = 0.001). However, no correlation was found between tumor clonality and patient survival (P = 0.630). The EGFR somatic aberrations in 58 multiple primary lung cancers, including vascular invasion associated with EGFR overexpression (P = 0.012) and mutation (P = 0.025), further suggested the potential benefits of target therapy of inoperable multiple primary lung cancers.

CONCLUSIONS

Our results suggest that analysis of somatic alterations in p53 and EGFR can significantly improve the clonality assessment and impact management of multiple primary lung cancer patients.

The prevalence of CDKN2A germ-line mutations and relative risk for cutaneous malignant melanoma: an international population-based study

Germ-line mutations of CDKN2A have been identified as strong risk factors for melanoma in studies of multiple-case families. However, an assessment of their relative risk for melanoma in the general population has been difficult because they occur infrequently. We addressed this issue using a novel population-based case-control study design in which "cases" have incident second- or higher-order melanomas [multiple primary melanoma (MPM)] and "controls" have incident first primary melanoma [single primary melanoma (SPM)]. Participants were ascertained from nine geographic regions in Australia, Canada, Italy, and United States. In the 1,189 MPM cases and 2,424 SPM controls who were eligible and available for analysis, the relative risk of a subsequent melanoma among patients with functional mutations who have an existing diagnosis of melanoma, after adjustments for age, sex, center, and known phenotypic risk factors, is estimated to be 4.3 (95% confidence interval, 2.3-7.7). The odds ratio varied significantly depending on the type of mutation involved. The results suggest that the relative risk of mutation carriers in the population may be lower than currently believed and that different mutations on the CDKN2A gene may confer substantially different risks of melanoma.

A design for cancer case-control studies using only incident cases: experience with the GEM study of melanoma

BACKGROUND

The population-based case-control study is not suited to the evaluation of rare genetic (or environmental) factors. The use of a novel case-control design in which cases have second primaries and controls are cancer survivors has been proposed for this purpose.

METHODS

We report results from an international study of melanoma that involved population-based ascertainment of incident cases of second or subsequent primary melanoma as the 'case' group and incident cases of first primary melanoma as the 'control' group. We evaluate the validity of the study design by comparing the results obtained for phenotypic factors that have been shown consistently to be associated with melanoma in previous conventional studies with the results from a conventional case-control study conducted in Connecticut and from literature reviews.

RESULTS

All but one of the known risk factors for melanoma were shown to be significantly associated with melanoma in our study, though the individual odds ratios appear to be somewhat attenuated relative to the magnitudes typically observed in the literature.

CONCLUSIONS

Patients with a second or subsequent primary cancer of a single type represent a potentially valuable and under-utilized resource for the study of cancer aetiology.

Identification of MGB1 as a marker in the differential diagnosis of lung tumors in patients with a history of breast cancer by analysis of publicly available SAGE data

The risk of developing second primary cancers is increased in patients with breast cancer. The lung is one of the major target organs, and therefore a differential diagnosis between primary and metastatic cancers is required for the treatment of lung tumors in patients with a history of breast cancer. However, biopsy specimens frequently result in small, fragmented tissues containing only a few, degenerated cancer cells. We attempted to find a useful marker for differential diagnosis, using the online SAGE database. We selected three molecules, small breast epithelial mucin (SBEM), prostate epithelium-specific Ets transcription factor (PDEF), and mammaglobin (MGB1), as potential markers for breast cancer. SBEM and PDEF proved of no use for practical differential diagnosis because they are expressed in the normal bronchus. In contrast, expression of MGB1 was detected in all 22 primary breast cancers, but not in 22 normal lung tissues. Furthermore, all 12 metastatic breast cancers examined demonstrated positive MGB1 transcripts, whereas one of 48 primary lung adenocarcinomas expressed MGB1. This suggests that MGB1 can serve as a differential molecular marker. In practice, prospective examination, using the nine cases with a history of breast cancer, confirmed the usefulness of MGB1 in differential diagnosis.

p53 mutation analysis for definite diagnosis of multiple primary lung carcinoma

BACKGROUND

The detection of a second tumor in patients with lung carcinoma raises the question whether this lesion is a metastasis or a second primary lung carcinoma. Patients cannot always be categorized satisfactorily according the criteria of multiple lung carcinoma proposed by Martini and Melamed. This may result in an inadequate treatment schedule in individual patients. Because p53 mutations can be used as clonal marker, the authors investigated whether p53 mutation analysis can differentiate between primary lung carcinomas and metastatic disease.

METHODS

Sixty-four tumors in 31 patients with synchronous and metachronous lung tumors were investigated by p53 mutation analysis.

RESULTS

In 21 patients, the tumors showed different p53 mutations, and therefore a definite diagnosis of multiple primary lung carcinoma was made. One of these patients did not meet the criteria of Martini and Melamed. In two other patients not matching these criteria, identical mutations were demonstrated in both tumors, indicating the presence of metastatic disease. In eight patients, analysis was not conclusive or possible.

CONCLUSIONS

p53 mutation analysis can be a useful tool to confirm or rule out multiple primary lung carcinoma, and the results confirm the criteria of Martini and Melamed. However, in patients not meeting these criteria, the diagnosis of multiple lung carcinoma still has to be considered, and metastatic disease has to be ruled out. P53 mutation analysis can be helpful for this purpose.

Follow-up of bronchial precancerous lesions and carcinoma in situ using fluorescence endoscopy

Little is known about the natural history of precancerous bronchial lesions. Histological changes occurring in 416 bronchial intraepithelial lesions (104 high-risk subjects) were assessed over a 2-yr period, using repeated follow-up autofluorescence endoscopies. During the study, 6 of 36 normal epitheliums became dysplastic; 47 of 152 metaplasia evolved to low-grade dysplasia, two progressed to carcinoma in situ, and one to invasive cancer; 6 of 169 low-grade epithelial lesions progressed to a persistent severe dysplasia; 10 of 27 severe dysplastic lesions and 28 of 32 carcinoma in situ persisted or progressed, respectively (p = 0.0005, severe dysplasia versus carcinoma in situ 24 mo outcome). Carcinoma in situ appeared more frequent in patients with a prior history or concomitant cancer (p = 0.003). Persistence of smoking during the study did not influence high-grade lesion outcome. Progression of low-grade epithelial lesions during the study occurred only in patients with at least a high-grade lesion in another site at baseline (9 of 147 lesions, 6.1%). Our study suggests that low-grade epithelial lesions could be safely followed-up at 2 yr in patients without high-grade lesions at baseline, whereas severe dysplasia should be treated if they persist at 3 mo. Immediate treatment of carcinoma in situ appears warranted.

Discrimination of double primary lung cancer from intrapulmonary metastasis by p53 gene mutation

When multiple synchronous lung tumours are identified, discrimination of multicentric lung cancers from intrapulmonary metastases by clinical findings is often difficult. We used genetic alterations in p53 gene as a discrimination marker of double primary lung cancers from single lung cancer with intrapulmonary metastasis. Twenty of 861 patients with primary lung cancer who underwent lung resection were selected as subjects because they showed synchronous double solid tumours of the same histological type in the unilateral lung without distant metastases. In addition, they had been diagnosed as lung carcinoma with intrapulmonary metastasis by clinical and histological findings. DNAs were extracted from paraffin-embedded tissue of paired tumours from these 20 patients. Exons 5-9 of the p53 gene were examined for genetic alterations in the tumours by polymerase chain reaction, single-strand conformation polymorphism analysis and subsequent DNA sequencing analysis. Three different patterns in the distribution of p53 mutations in double lung tumours were observed: [A] mutation in only one of the tumours (four cases), [B] different mutations in the tumours (two cases), and [C] same mutation in both tumours (one case). The cases of [A] or [B] patterns could be classified as double primary lung cancers, while the case of the [C] pattern was suggested to be lung cancer with intrapulmonary metastasis. These results suggested that the multicentric cancers were more frequent than the intrapulmonary metastatic cancers in double cancer cases.

Bronchioloalveolar adenocarcinoma of lung: monoclonal origin for multifocal disease

In an attempt to understand the histogenesis and molecular pathogenesis of multifocal bronchioloalveolar lung carcinoma (BAC) we studied 28 cases of BAC using a topographic genotyping approach for the presence of K-ras exon 1 mutations and p53 loss of heterozygosity (LOH). This analytical approach demonstrated K-ras exon 1 mutations in 12.5% of solitary BACs, 40% of BACs with microscopic or macroscopic satellite lesions, and 60% of BACs with intrathoracic metastases. In all cases with K-ras mutations, the identical point mutation was present in the primary, satellite, and intrathoracic metastatic lesions. When p53 LOH was demonstrated in the primary lesion, it was also detected in the satellites and intrathoracic metastases. No significant association was noted between the presence of K-ras mutations and p53 LOH. The results strongly support a monoclonal origin of multifocal BACs. Furthermore, the findings support the theories explaining the origin of multifocal BAC by intraalveolar route of spread, intrapulmonary lymphatic spread, or aerosolization leading to implantation at different sites. A trend toward an increased frequency of K-ras mutations and p53 LOH in BACs with satellites or metastases compared to solitary BACs was noted.

Second lung cancers in patients after treatment for an initial lung cancer

BACKGROUND

Prospectively and retrospectively identified patient cohorts that were successfully treated for primary lung cancer have been followed to document the rate of development of and the effectiveness of treatment of second lung cancers. This review was performed to assess rates of second lung cancer development, factors associated with the development of these cancers, and the success of their treatment.

METHODS

The MEDLINE database was searched to identify articles published in English concerning lung cancers, second primary cancers, treatment of these cancers, and patient survival.

RESULTS

The risk of developing a second lung cancer in patients who survived resection of a non-small-cell lung cancer is approximately 1%-2% per patient per year. Approximately one half of the patients who develop second non-small-cell lung cancers can have these tumors resected. The median survival from diagnosis of a second lung cancer in these patients is between 1 and 2 years, with a 5-year survival of approximately 20% (range, 4%-32%). The average risk of developing a second lung cancer in patients who survived small-cell lung cancer is approximately 6% per patient per year. For patients who survived small-cell cancer, the risk increases from approximately 2% to greater than 10% per patient per year 10 years after initial treatment. Only 7% (range, 6%-12%) of patients treated for small-cell lung cancer survive 2 years or more. Survivors who continue to smoke cigarettes have an increased risk of developing a second lung cancer.

CONCLUSIONS

In patients surviving an initial lung cancer, the cumulative risk for the development of a second primary lung cancer makes this cancer a common cause of death. The high risk of developing a second lung cancer makes patients with these cancers an important population for study of surveillance strategies and chemoprevention agents.