Guideline Recommendations for Testing of ALK Gene Rearrangement in Lung Cancer: A Proposal of the Korean Cardiopulmonary Pathology Study Group

Molecular Characteristics of Radon Associated Lung Cancer Highlights MET Alterations

Simple Summary

Lung cancer (LC) is the leading cause of cancer death worldwide. After smoking, one of the most prominent risk factors for LC development is radon (Rn) exposure. In our study we analysed and compared the genetic landscape of LC patients from a Rn exposed village with local matched non-exposed patients. Within the concordant genetic landscape, an increase in genetic MET proto-oncogene, receptor tyrosine kinase (MET) alteration in the Rn-exposed cohort was monitored, underlining the importance of routine MET testing and potential to enable a more effective treatment for this specific subgroup.

Abstract

Effective targeted treatment strategies resulted from molecular profiling of lung cancer with distinct prevalent mutation profiles in smokers and non-smokers. Although Rn is the second most important risk factor, data for Rn-dependent driver events are limited. Therefore, a Rn-exposed cohort of lung cancer patients was screened for oncogenic drivers and their survival and genetic profiles were compared with data of the average regional population. Genetic alterations were analysed in 20 Rn-exposed and 22 histologically matched non-Rn exposed LC patients using targeted Next generation sequencing (NGS) and Fluorescence In Situ Hybridization (FISH). Sufficient material and sample quality could be obtained in 14/27 non-exposed versus 17/22 Rn-exposed LC samples. Survival was analysed in comparison to a histologically and stage-matched regional non-exposed lung cancer cohort (n = 51) for hypothesis generating. Median overall survivals were 83.02 months in the Rn-exposed and 38.7 months in the non-exposed lung cancer cohort (p = 0.22). Genetic alterations of both patient cohorts were in high concordance, except for an increase in MET alterations and a decrease in TP53 mutations in the Rn-exposed patients in this small hypothesis generating study.

Testing for EGFR Mutations and ALK Rearrangements in Advanced Non-Small-Cell Lung Cancer: Considerations for Countries in Emerging Markets

The treatment of patients with advanced non-small-cell lung cancer (NSCLC) in recent years has been increasingly guided by biomarker testing. Testing has centered on driver genetic alterations involving the epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) rearrangements. The presence of these mutations is predictive of response to targeted therapies such as EGFR tyrosine kinase inhibitors (TKIs) and ALK TKIs. However, there are substantial challenges for the implementation of biomarker testing, particularly in emerging countries. Understanding the barriers to testing in NSCLC will be key to improving molecular testing rates worldwide and patient outcomes as a result. In this article, we review EGFR mutations and ALK rearrangements as predictive biomarkers for NSCLC, discuss a selection of appropriate tests and review the literature with respect to the global uptake of EGFR and ALK testing. To help improve testing rates and unify procedures, we review our experiences with biomarker testing in China, South Korea, Russia, Turkey, Brazil, Argentina and Mexico, and propose a set of recommendations that pathologists from emerging countries can apply to assist with the diagnosis of NSCLC.

Molecular biomarker testing for non-small cell lung cancer: consensus statement of the Korean Cardiopulmonary Pathology Study Group

Molecular biomarker testing is the standard of care for non–small cell lung cancer (NSCLC) patients. In 2017, the Korean Cardiopulmonary Pathology Study Group and the Korean Molecular Pathology Study Group co-published a molecular testing guideline which contained almost all known genetic changes that aid in treatment decisions or predict prognosis in patients with NSCLC. Since then there have been significant changes in targeted therapies as well as molecular testing including newly approved targeted drugs and liquid biopsy. In order to reflect these changes, the Korean Cardiopulmonary Pathology Study Group developed a consensus statement on molecular biomarker testing. This consensus statement was crafted to provide guidance on what genes should be tested, as well as methodology, samples, patient selection, reporting and quality control.

Microfluidics-based immunofluorescence for fast staining of ALK in lung adenocarcinoma

Background

Anaplastic lymphoma kinase (ALK) is a key oncogenic driver in lung adenocarcinoma patients and its fusion proteins are routinely assessed. The microfluidic tissue processor (MTP) device is based on a chip-confined low-volume technology allowing for rapid immunohistochemistry/immunofluorescence (IHC/IF) stainings of formalin-fixed paraffin-embedded (FFPE) or frozen tissue samples.

Methods

A novel ALK IF protocol was developed for the MTP device using the primary mouse anti-human ALK antibody clone 5A4. FFPE tumor whole sections from 14 resected lung adenocarcinoma patients documented to be ALK positive (ALK+) by automated chromogenic IHC and/or FISH were used. MTP-derived IF immunoreactivity was measured by computerized analysis of digitalized images on individual frames of tumor epithelia and surrounding stroma, using an ImageJ plug-in.

Results

The 5A4 antibody yielded saturated immunoreactivity at an incubation time of 4 min on a titration curve ranging from 2 to 32 min. Total staining time on the MTP device was 18 min including secondary IgG Alexa Fluor 647. MTP-based ALK IF confirmed all 12 cases; with epithelial signal above stromal staining based on computerized pixel-based measurement. MTP-IF (mean intensity levels 458 to 1301) and chromogenic IHC (H-score 120 to 300) showed an equal range of variation of 2.8 and 2.5 folds, respectively, and a trend for direct correlation (p-value 0.051).

Conclusion

The newly developed protocol for immunofluorescent detection of ALK protein with the MTP device confirms chromogenic IHC results on FFPE lung adenocarcinoma specimens. MTP-based IF is fast and reliable. We foresee this study to be a first step opening the road for further realization of microfluidic-based assays for rapid simultaneous detection of targetable oncogenic and immune-system related markers in their topographical context to investigate tumour heterogeneity and micro-environmental interactions.

Electronic supplementary material

The online version of this article (10.1186/s13000-018-0757-1) contains supplementary material, which is available to authorized users.

Molecular testing and treatment patterns for patients with advanced non-small cell lung cancer: PIvOTAL observational study

Background

The goals of this multinational retrospective study were to describe treatment patterns and survival outcomes by receipt of molecular testing and molecular status of patients with advanced non-small cell lung cancer (NSCLC).

Methods

This chart review study, conducted in Italy, Spain, Germany, Australia, Japan, Korea, Taiwan, and Brazil, included 1440 patients with newly diagnosed advanced (stage IIIB/IV) NSCLC initiating systemic therapy from January 2011 through June 2013, with follow-up until July 2016. We evaluated treatment patterns and survival by histology, line of therapy, molecular testing, and test results for epidermal growth factor receptor (EGFR) mutation and/or anaplastic lymphoma kinase (ALK) rearrangement. Country-specific data were analyzed descriptively and presented as ranges (lowest to highest country). Overall survival (OS) was estimated using Kaplan-Meier method.

Results

Patients with ≥1 molecular test varied from 43% (Brazil) to 85% (Taiwan). Numerically greater proportions of patients who were female, Asian, or never/former-smokers, and those with nonsquamous histology or stage-IV NSCLC, received a test. Testing was common for nonsquamous NSCLC (54%, Brazil, to 91%, Taiwan), with positive EGFR and ALK tests from 17% (Brazil and Spain) to 67% (Taiwan) and from 0% (Brazil) to 60% (Taiwan), respectively. First-line treatment regimens for nonsquamous NSCLC with positive EGFR/ALK tests included targeted therapy for 30% (Germany) to 89% (Japan); with negative/inconclusive test results, platinum-based combinations for 88% (Japan) to 98% (Brazil); and if not tested, platinum-based combinations for 80% (Australia) to 95% (Japan), except in Taiwan, where 44% received single agents. Median OS from first-line therapy initiation was 10.0 (Japan) to 26.7 (Taiwan) months for those tested and 7.6 (Australia/Brazil) to 19.3 (Taiwan) months for those not tested.

Conclusions

We observed substantial variation among countries in testing percentages, treatment patterns, and survival outcomes. Efforts to optimize molecular testing rates should be implemented in the context of each country’s health care scenario.

5'/ 3' imbalance strategy to detect ALK fusion genes in circulating tumor RNA from patients with non-small cell lung cancer

Background

Detecting an ALK fusion gene in patients with non-small cell lung cancer (NSCLC) could provide evidence to guide individualized therapy.

Methods

The 5′/3′ imbalance strategy for quantitative reverse transcription-PCR (RT-qPCR) was developed to detect ALK fusion genes in circulating tumor RNA (ctRNA) of NSCLC patients.

Results

This method was validated in patients with the ALK fusion gene confirmed by next generation sequencing (NGS). The amount of the ALK fusion gene detected by the new method ranged from 33.2 to 987.4, (mean 315.2), in the patients confirmed to have the ALK fusion gene (+). This is much higher than the amount of fusion gene detected in the patients who are negative for the ALK fusion gene (−). The amount detected in the ALK fusion gene (−) samples ranged from 0.36 to 13.04, (mean 4.58). In 188 NSCLC patients, the specificity and sensitivity of the method was compared to that of the FISH method. About 10.64% of the patients showed higher ALK fusion gene expression, and were classified as ALK fusion gene (+). This is identical to the percentage of patients detected by the FISH method to be ALK fusion gene (+). The cutoff value for diagnosis of ALK fusion (+) is 32.9 as determined by this method.

Conclusions

A new RT-PCR method using a 5′/3′ imbalance strategy was developed, with high specificity and sensitivity, for detection of the ALK fusion gene in ctRNA of NSCLC patients. This method can rapidly detect ALK fusion genes in patients, which will be helpful for guiding targeted therapy, particularly the individualized usage of TKIs in these patients.

Updated Molecular Testing Guideline for the Selection of Lung Cancer Patients for Treatment With Targeted Tyrosine Kinase Inhibitors: Guideline From the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology

CONTEXT

- In 2013, an evidence-based guideline was published by the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology to set standards for the molecular analysis of lung cancers to guide treatment decisions with targeted inhibitors. New evidence has prompted an evaluation of additional laboratory technologies, targetable genes, patient populations, and tumor types for testing.

OBJECTIVE

- To systematically review and update the 2013 guideline to affirm its validity; to assess the evidence of new genetic discoveries, technologies, and therapies; and to issue an evidence-based update.

DESIGN

- The College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology convened an expert panel to develop an evidence-based guideline to help define the key questions and literature search terms, review abstracts and full articles, and draft recommendations.

RESULTS

- Eighteen new recommendations were drafted. The panel also updated 3 recommendations from the 2013 guideline.

CONCLUSIONS

- The 2013 guideline was largely reaffirmed with updated recommendations to allow testing of cytology samples, require improved assay sensitivity, and recommend against the use of immunohistochemistry for EGFR testing. Key new recommendations include ROS1 testing for all adenocarcinoma patients; the inclusion of additional genes ( ERBB2, MET, BRAF, KRAS, and RET) for laboratories that perform next-generation sequencing panels; immunohistochemistry as an alternative to fluorescence in situ hybridization for ALK and/or ROS1 testing; use of 5% sensitivity assays for EGFR T790M mutations in patients with secondary resistance to EGFR inhibitors; and the use of cell-free DNA to "rule in" targetable mutations when tissue is limited or hard to obtain.

Updated Molecular Testing Guideline for the Selection of Lung Cancer Patients for Treatment With Targeted Tyrosine Kinase Inhibitors: Guideline From the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology

CONTEXT

In 2013, an evidence-based guideline was published by the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology to set standards for the molecular analysis of lung cancers to guide treatment decisions with targeted inhibitors. New evidence has prompted an evaluation of additional laboratory technologies, targetable genes, patient populations, and tumor types for testing.

OBJECTIVE

To systematically review and update the 2013 guideline to affirm its validity; to assess the evidence of new genetic discoveries, technologies, and therapies; and to issue an evidence-based update.

DESIGN

The College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology convened an expert panel to develop an evidence-based guideline to help define the key questions and literature search terms, review abstracts and full articles, and draft recommendations.

RESULTS

Eighteen new recommendations were drafted. The panel also updated 3 recommendations from the 2013 guideline.

CONCLUSIONS

The 2013 guideline was largely reaffirmed with updated recommendations to allow testing of cytology samples, require improved assay sensitivity, and recommend against the use of immunohistochemistry for EGFR testing. Key new recommendations include ROS1 testing for all adenocarcinoma patients; the inclusion of additional genes (ERBB2, MET, BRAF, KRAS, and RET) for laboratories that perform next-generation sequencing panels; immunohistochemistry as an alternative to fluorescence in situ hybridization for ALK and/or ROS1 testing; use of 5% sensitivity assays for EGFR T790M mutations in patients with secondary resistance to EGFR inhibitors; and the use of cell-free DNA to "rule in" targetable mutations when tissue is limited or hard to obtain.

Updated Molecular Testing Guideline for the Selection of Lung Cancer Patients for Treatment With Targeted Tyrosine Kinase Inhibitors: Guideline From the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology

CONTEXT

In 2013, an evidence-based guideline was published by the College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology to set standards for the molecular analysis of lung cancers to guide treatment decisions with targeted inhibitors. New evidence has prompted an evaluation of additional laboratory technologies, targetable genes, patient populations, and tumor types for testing.

OBJECTIVE

To systematically review and update the 2013 guideline to affirm its validity; to assess the evidence of new genetic discoveries, technologies, and therapies; and to issue an evidence-based update.

DESIGN

The College of American Pathologists, the International Association for the Study of Lung Cancer, and the Association for Molecular Pathology convened an expert panel to develop an evidence-based guideline to help define the key questions and literature search terms, review abstracts and full articles, and draft recommendations.

RESULTS

Eighteen new recommendations were drafted. The panel also updated 3 recommendations from the 2013 guideline.

CONCLUSIONS

The 2013 guideline was largely reaffirmed with updated recommendations to allow testing of cytology samples, require improved assay sensitivity, and recommend against the use of immunohistochemistry for EGFR testing. Key new recommendations include ROS1 testing for all adenocarcinoma patients; the inclusion of additional genes (ERBB2, MET, BRAF, KRAS, and RET) for laboratories that perform next-generation sequencing panels; immunohistochemistry as an alternative to fluorescence in situ hybridization for ALK and/or ROS1 testing; use of 5% sensitivity assays for EGFR T790M mutations in patients with secondary resistance to EGFR inhibitors; and the use of cell-free DNA to "rule in" targetable mutations when tissue is limited or hard to obtain.

Molecular Testing of Lung Cancers

Targeted therapies guided by molecular diagnostics have become a standard treatment of lung cancer. Epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements are currently used as the best predictive biomarkers for EGFR tyrosine kinase inhibitors and ALK inhibitors, respectively. Besides EGFR and ALK, the list of druggable genetic alterations has been growing, including ROS1 rearrangements, RET rearrangements, and MET alterations. In this situation, pathologists should carefully manage clinical samples for molecular testing and should do their best to quickly and accurately identify patients who will benefit from precision therapeutics. Here, we grouped molecular biomarkers of lung cancers into three categories—mutations, gene rearrangements, and amplifications—and propose expanded guidelines on molecular testing of lung cancers.

[Gene Expression and Clinical Characteristics of Molecular Targeted Therapy in Non-small Cell Lung Cancer Patients in Shandong]

BACKGROUND

Molecular targeted therapy has gradually become an important treatment for lung cancer, the aim of this research is to analyze the clinicopathologic features associated with the gene mutation status of epidermal growth factor receptor (EGFR), echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK), ROS proto-oncogene 1, receptor tyrosine kinase (ROS1) and Kirsten rat sarcoma viral oncogene (KRAS) in non-small cell lung cancer (NSCLC) patients and determine the most likely populations to benefit from molecular target therapy treatment.

METHODS

The mutation status of EGFR, EML4-ALK fusion gene, ROS1 and KARS gene were determined by Real-time PCR, the relationship between clinical pathologic features and concomitant gene were analyzed with χ2 test by SPSS software 19.0.

RESULTS

A total of 514 specimens from Shandong tumor hospital were collected from NSCLC patients between January 2014 and May 2016. The total mutation rate of EGFR gene was 36.70%, major occurred in exon 19 (36.61%) and exon 21 (51.36%), respectively, and EGFR mutations usually occurred in female, non-smoking and adenocarcinoma patients (P<0.05). The total rearrangements rate of EML4-ALK fusion gene was 9.37%, EML4-ALK fusion gene usually occurred in younger age (≤60 yr) and non-smoking patients (P<0.05). Mutations were not related to gender and pathological type (P>0.05). ROS1 fusion gene was detected in 136 cases, the positive rate was 3.67%, all patients were 60 years old, and the difference was statistically significant (P<0.05). Only 23 samples were tested KARS gene mutations, two of them were positive and the positive rate was 8.70%. They all occurred in non-smoker and adenocarcinoma patients. No mutation was detected to coexist in EGFR, EML4-ALK and KARS gene mutation.

CONCLUSIONS

EGFR, EML4-ALK, ROS1 and KRAS defines different molecular subset of NSCLC with distinct characteristic, which provides a new option for the clinical treatment of patients with NSCLC.

Expanded Circulating Tumor Cells from a Patient with ALK-Positive Lung Cancer Present with EML4-ALK Rearrangement Along with Resistance Mutation and Enable Drug Sensitivity Testing: A Case Study

The emergence of liquid biopsy using circulating tumor cells (CTCs) as a resource to identify genomic alterations in cancer presents new opportunities for diagnosis, therapy, and surveillance. We identified EML4-ALK gene rearrangement in expanded CTCs from a patient with ALK-positive lung adenocarcinoma. At the time of radiographic progression, CTCs obtained from the patient revealed a drug resistance mutation (i.e., L1196M on the ALK gene). CTCs were expanded ex vivo and drug sensitivity testing was performed using two ALK inhibitors, crizotinib and ceritinib. The half maximal inhibitory concentration of ceritinib was 1664 nM compared with crizotinib (2268 nM), showing that ceritinib was a more potent ALK inhibitor. We show that it is feasible to detect serial genetic alterations in expanded CTCs and perform in vitro drug screening. These findings support the clinical utility of CTCs not only for diagnosis, but also a potential tool for drug sensitivity testing in distinct subsets of lung cancer and for personalized precision medicine.

Novel ALK fusion partners in lung cancer

Detection of ALK rearrangements in patients with non-small cell lung cancer (NSCLC) presents a significant technical challenge due to the existence of multiple translocation partners and break-points. To improve the performance of PCR-based tests, we utilized the combination of 2 assays, i.e. the variant-specific PCR for the 5 most common ALK rearrangements and the test for unbalanced 5'/3'-end ALK expression. Overall, convincing evidence for the presence of ALK translocation was obtained for 34/400 (8.5%) cases, including 14 EML4ex13/ALKex20, 12 EML4ex6/ALKex20, 3 EML4ex18/ALKex20, 2 EML4ex20/ALKex20 variants and 3 tumors with novel translocation partners. 386 (96.5%) out of 400 EGFR mutation-negative NSCLCs were concordant for both tests, being either positive (n = 26) or negative (n = 360) for ALK translocation; 49 of these samples (6 ALK+, 43 ALK-) were further evaluated by FISH, and there were no instances of disagreement. Among the 14 (3.5%) "discordant" tumors, 5 demonstrated ALK translocation by the first but not by the second PCR assay, and 9 had unbalanced ALK expression in the absence of known ALK fusion variants. 5 samples from the latter group were subjected to FISH, and the presence of translocation was confirmed in 2 cases. Next generation sequencing analysis of these 2 samples identified novel translocation partners, DCTN1 and SQSTM1; furthermore, the DCTN1/ALK fusion was also found in another NSCLC sample with unbalanced 5'/3'-end ALK expression, indicating a recurrent nature of this translocation. We conclude that the combination of 2 different PCR tests is a viable approach for the diagnostics of ALK rearrangements. Systematic typing of ALK fusions is likely to reveal new NSCLC-specific ALK partners.

Strategic management of transthoracic needle aspirates for histological subtyping and EGFR testing in patients with peripheral lung cancer: An institutional experience

BACKGROUND

Lung cancer therapy is personalized based on the histological subtype and molecular status. Totally, 70% of lung cancer patients present in advanced stages and are diagnosed on small biopsy or cytology specimens, hence an accurate but tissue-sparing approach is necessary. This study aimed to demonstrate efficient utilization of cell block (CB) on transthoracic needle aspiration (TTNA) for lung cancer subtyping, and to investigate the usefulness of needle washing after TTNA for assessing EGFR molecular status.

METHODS

Each TTNA specimen from the 79 peripheral lung masses was divided into three parts; liquid-based cytology (LBC), CB (with or without immunohistochemistry), and needle washing for analysis of EGFR mutation using peptide nucleic acid-mediated real-time PCR clamping.

RESULTS

Totally 79 specimens were diagnosed as malignancy, 75 (94.9%), benign, 3 (3.8%), and inadequate specimen, 1 (1.3%). The combination of LBC and CB (92.0%) showed a higher diagnostic yield for definitive subtyping of lung cancer than LBC alone (72.0%). Of the 75 malignant cases, 17 (22.7%) showed an EGFR mutation in needle washing specimens. EGFR mutational status was compared in all paired needle washing and scraped CBs with a 100% concordance.

CONCLUSIONS

We hereby proposed a strategy to maximize biological information retrieval from a limited TTNA specimen in patients with peripheral lung cancer. This algorithm indicated CB preparation for accurate histological subtyping and waste needle washing for molecular testing.

Role of biopsy sampling for diagnosis of early and progressed hepatocellular carcinoma

The current guidelines for the diagnosis of hepatocellular carcinoma (HCC) recommend liver biopsy for hepatic nodules which do not demonstrate the typical features of HCC on imaging. Thus, while not all HCCs are biopsied for histological confirmation, the nodules that pathologists now encounter on biopsy specimens are frequently well-differentiated early HCCs. This paper reviews the pathological features of HCC and its precursor lesions on liver biopsy specimens, with special emphasis on the differential diagnosis between well-differentiated HCCs and high-grade dysplastic nodules, and discusses the different roles of liver biopsy in diagnosis and management of early and progressed HCC. The potential role of liver biopsy for the development of molecular markers to predict prognosis and response to targeted therapy is also discussed.

Molecular pathology of lung cancer: current status and future directions

The rapid development of targeted therapies has enormously changed the clinical management of lung cancer patients over the past decade; therefore, molecular testing, such as epidermal growth factor receptor (EGFR) gene mutations or anaplastic lymphoma kinase (ALK) gene rearrangements, is now routinely used to predict the therapeutic responses in lung cancer patients. Moreover, as technology and knowledge supporting molecular testing is rapidly evolving, the landscape of targetable genomic alterations in lung cancer is expanding as well. This article will summarize the current state of the most commonly altered and most clinically relevant genes in lung cancer along with a brief review of potential future developments in molecular testing of lung cancer.

Epidermal growth factor receptor mutations and anaplastic lymphoma kinase rearrangements in lung cancer with nodular ground-glass opacity

Background

Nodular ground-glass opacities (nGGO) are a specific type of lung adenocarcinoma. ALK rearrangements and driver mutations such as EGFR and K-ras are frequently found in all types of lung adenocarcinoma. EGFR mutations play a role in the early carcinogenesis of nGGOs, but the role of ALK rearrangement remains unknown.

Methods

We studied 217 nGGOs resected from 215 lung cancer patients. Pathology, tumor size, tumor disappearance rate, and the EGFR and ALK markers were analyzed.

Results

All but one of the resected nGGOs were adenocarcinomas. ALK rearrangements and EGFR mutations were found in 6 (2.8%) and 119 (54.8%) cases. The frequency of ALK rearrangement in nGGO was significantly lower than previously reported in adenocarcinoma. Advanced disease stage (p = 0.018) and larger tumor size (p = 0.037) were more frequent in the ALK rearrangement-positive group than in ALK rearrangement-negative patients. nGGOs with ALK rearrangements were associated with significantly higher pathologic stage and larger maximal and solid diameter in comparison to EGFR-mutated lesions.

Conclusion

ALK rearrangement is rare in lung cancer with nGGOs, but is associated with advanced stage and larger tumor size, suggesting its association with aggressive progression of lung adenocarcinoma. ALK rearrangement may not be important in early pathogenesis of nGGO.