Multifocal Lung Adenocarcinomas Research Articles

PP01.66 An unusual presentation and delayed diagnosis of multifocal lung adenocarcinoma

PP01.66 An unusual presentation and delayed diagnosis of multifocal lung adenocarcinoma

Clinical impact of EGFR and KRAS mutations in surgically treated unifocal and multifocal lung adenocarcinoma.

Epidermal growth factor receptor (EGFR) and Kirsten rat sarcoma (KRAS) are the two most common oncogenic drivers in lung adenocarcinoma, and their roles still need further exploration. Here we aimed to compare the clinical impact of EGFR and KRAS mutations on disease progression in resected unifocal and multifocal lung adenocarcinoma. Clinicopathologic and genomic data were collected for patients who underwent resection of lung adenocarcinoma from 2008 to 2022 at Stanford University Hospital. Retrospective review was performed in 241 patients whose tumors harbored EGFR (n=150, 62.2%) or KRAS (n=91, 37.8%) mutations. Clinical outcome was analyzed with special attention to the natural history of secondary nodules in multifocal cases wherein the dominant tumor had been resected. We confirm that compared with EGFR mutations, patients with KRAS mutations had more smokers, larger tumor size, higher TNM stage, higher positron emission tomography (PET)/computed tomography (CT) standard uptake value max, higher tumor mutation burden, and worse disease-free survival and overall survival on univariate analysis. For patients with multifocal pulmonary nodules, the median follow-up of unresected secondary nodules was 55 months. Secondary nodule progression-free survival (SNPFS) was significantly worse for patients with KRAS mutations than those with EGFR mutations (mean 40.3±6.6 vs. 67.7±6.5 months, P=0.004). Univariate analysis showed tumor size, tumor morphology, pathologic TNM stage, and KRAS mutations were significantly associated with SNPFS, while multivariate analysis showed only KRAS mutations were independently associated with worse SNPFS (hazard ratio 1.752, 95% confidence interval: 1.017-3.018, P=0.043). Resected lung adenocarcinomas with KRAS mutations have more aggressive clinicopathological features and confer worse prognosis than those with EGFR mutations. Secondary pulmonary nodules in multifocal cases with dominant KRAS-mutant tumors have more rapid progression of the secondary nodules.

Abstract CT278: [DREAM] Double lung transplant registry aimed for lung-limited malignancies - a prospective registry study for medically refractory cancers

Abstract BackgroundAdenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) are listed as ‘special circumstances’ for lung transplantation according to a consensus document from the International Society for Heart and Lung Transplantation (ISHLT) (Weill D et al., 2015). Five studies have reported on lung transplantation in carefully selected subsets of patients with multifocal lung adenocarcinoma (Raemdonck DV et al., 2016; Glanville AR et al., 2018). The 5-year survival rate of bilateral sequential lung transplantation was estimated at over 50% in patients with multifocal BAC, invasive adenocarcinoma, and NSCLC (Ahmad U et al., 2012; Paloyan EB et al., 2000; Zorn GL et al., 2003; de Perrot M et al., 2004). Another a case series reported a post-transplant recurrence-free survival of 23 to 56 months in three patients (Garver RI et al., 1999). Moreover, there is an unmet need for patients who have lung-limited metastasis after successful treatment for primary tumors such as sarcomas or colorectal cancer (CRC). As with liver transplantation for CRC patients who have liver-confined metastases (Dueland S et at., 2020; Hernandez-Alejandro R et al., 2022), the applicability of lung transplantation in lung-limited metastatic patients should be explored. There is also an unmet need for patients with respiratory failure with a history of cancer in the last 5 years. MethodsThis is a prospective registration trial to evaluate outcomes of patients who undergo double lung transplantation for the treatment of the select groups of medically refractory cancers (primary lung cancers or metastatic cancers in lungs). Overall survival (OS), disease-free survival (DFS), allograft rejection (AR) and allograft survival (AS) as well as molecular and genetic biomarkers will be monitored to investigate the correlation with prognosis.The study duration will be 10 years including surveillance. Recruitment is to occur during the first 5 years of the study. The goal is to enroll 125 participants through the Northwestern Medicine Clinical Programs.Essential Criteria:1.The tumor should be without any extrapulmonary metastasis as determined by standard of care diagnostic and staging workup.2.All standard of care or experimental oncological treatments known to improve survival should have failed or deemed infeasible 3.Patients should meet the general criteria for lung transplant evaluation and listing Study cohorts:•Cohort A: Primary lung cancers - Examples include, but not limited to, invasive mucinous/non-mucinous non-small cell lung cancers and multifocal carcinomas.•Cohort B: Metastatic cancers to the lung only - Examples include, but not limited to, germ cell tumors, head & neck tumors, colorectal tumors, renal cell tumors, testicular cancers.•Cohort C: Respiratory failure with a history of cancer in the last 5 years- Examples include, but not limited to interstitial lung disease (ILD), pulmonary fibrosis (idiopathic or secondary), advanced chronic obstructive pulmonary disease (COPD), bronchiectasis, emphysema, cystic fibrosis (CF), emphysema due to alpha-1 antitrypsin deficiency, and pulmonary arterial hypertension (PAH) Clinical trial registry number : NCT05671887.Enrollment began November 16, 2022. Trial is open and continues to enroll participants as of Jan 8, 2024. Citation Format: Young Kwang Chae, Liam Il-Young Chung, Rade Tomic, Ankit Bharat. [DREAM] Double lung transplant registry aimed for lung-limited malignancies - a prospective registry study for medically refractory cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT278.

Long-Term Survival and CANARY-Based Artificial Intelligence for Multifocal Lung Adenocarcinoma

ObjectiveTo investigate whether an artificial intelligence (AI)–based model can predict tumor invasiveness in patients with multifocal lung adenocarcinoma (MFLA). Patients and MethodsPatients with MFLA who underwent surgical resection were enrolled to a prospective registry trial (NCT01946100). Each identified nodule underwent retrospective computer-aided nodule assessment and risk yield (CANARY)–based AI to determine a quantitative degree of invasiveness. Data regarding age, sex, medical and surgical management, and survival were collected and analyzed. Pathologic review was performed by a pulmonary pathologist with comprehensive histologic subtyping. ResultsFrom January 1, 2013, through December 31, 2018, 68 patients with MFLA underwent at least 1 surgical resection. Five-year survival for the cohort was 91%, and 10-year survival was 73.6%. No significant differences in survival were observed when separated by sex, number, or size of the nodules. A 10-year survival trend was seen when comparing patients with unilateral (100% survival) vs bilateral disease (66%). Retrospective CANARY-based AI analysis demonstrated that the majority of the nodules present at the time of diagnosis (229/302; 75.8%) were classified good, with an average score of 0.19, suggesting indolent clinical behavior and noninvasive pathology. However, AI-CANARY scores of the surgically removed nodules were significantly higher compared with those of the nonresected nodules (P=.001). ConclusionThe long-term survival for patients with N0, M0 MFLA who have undergone surgical resection may approach those of stage I non–small cell lung cancer. CANARY-based AI has the potential to stratify individual nodules to help guide surgical intervention versus observation of nodules. Trial Registrationclinicaltrials.gov Identifier: NCT01946100

Abstract CT051: Double lung transplant registry aimed for lung-limited malignancies (DREAM) - a prospective registry study of bilateral lung transplantation for medically refractory cancers confined to the lungs

Abstract Background: According to a consensus document from the International Society for Heart and Lung Transplantation (ISHLT), adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) are listed as ‘special circumstances’ for lung transplantation (Weill D et al., 2015). There have been five reported studies of lung transplantation in carefully selected subsets of patients with multifocal lung adenocarcinoma (Raemdonck DV et al., 2016; Glanville AR et al., 2018). The 5-year survival rate of bilateral sequential lung transplantation was estimated at over 50% in patients with multifocal BAC, invasive adenocarcinoma, and NSCLC (Ahmad U et al., 2012; Paloyan EB et al., 2000; Zorn GL et al., 2003; de Perrot M et al., 2004). In 1999, a case series reported a post-transplant recurrence-free survival of 23 to 56 months in three patients (Garver RI et al., 1999). There is also an unmet need for patients who have lung-limited metastasis after successful treatment for primary tumors such as sarcomas or colorectal cancer (CRC). As with liver transplantation for CRC patients who have liver-confined metastases (Dueland S et at., 2020; Hernandez-Alejandro R et al., 2022), the applicability of lung transplantation in lung-limited metastasis patients should be explored. Methods: This is a prospective registration trial to evaluate outcomes of patients who undergo lung transplantation for the treatment of the select groups of medically refractory cancers (primary lung cancers or metastatic cancers in lungs). Overall survival (OS), disease-free survival (DFS), allograft rejection (AR) and allograft survival (AS) will be monitored as well as molecular and genetic biomarkers to investigate the correlation with prognosis. The study duration will be 10 years including surveillance. Recruitment to occur during the first 5 years of the study. The goal is to enroll 175 participants through the Lurie Comprehensive Cancer Center of Northwestern University. Essential Criteria: The tumor should be without any involvement of mediastinal lymph nodes involvement confirmed by endobronchial ultrasound (EBUS) or mediastinoscopy. The patient who are resistant or refractory to or without available standard of care treatment options or experimental treatment options that are known to increase survival outcome. Study cohorts: • Cohort A: Primary lung cancers - Examples include, but not limited to, invasive mucinous/non-mucinous non-small cell lung cancers and multifocal carcinomas. • Cohort B: Metastatic cancers to the lung only - Examples include, but not limited to, germ cell tumors, head & neck tumors, colorectal tumors, renal cell tumors, testicular cancers. Clinical trial registry number: NCT05671887. Enrollment began November 16, 2022. Trial is open and recruiting as of January 12, 2023. Citation Format: Young Chae, Liam Il-Young Chung, Rade Tomic, Ankit Bharat. Double lung transplant registry aimed for lung-limited malignancies (DREAM) - a prospective registry study of bilateral lung transplantation for medically refractory cancers confined to the lungs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT051.

A novel NGS‐based diagnostic algorithm for classifying multifocal lung adenocarcinomas in pN0M0 patients

The classification of multifocal lung adenocarcinomas (MLAs), including multiple primary lung adenocarcinomas (MPLAs) and intrapulmonary metastases (IPMs), has great clinical significance in staging and treatment determination. However, the application of molecular approaches in pN0M0 MLA diagnosis has not been well investigated. Here, we performed next-generation sequencing (NGS) analysis in 45 pN0M0 MLA patients (101 lesion pairs) who were initially diagnosed as having MPLA by comprehensive histologic assessment (CHA). Five additional patients with intrathoracic metastases were used as positive controls, while 197 patients with unifocal lung adenocarcinomas (425 random lesion pairs) were used as negative controls. By utilizing a predefined NGS criterion, all IPMs in the positive control group could be accurately classified, whereas 13 lesion pairs (3.1%) in the negative control cohort were misdiagnosed as IPMs. Additionally, 14 IPM lesion pairs were diagnosed in the study group, with at least 7 misdiagnoses. We thus developed a refined algorithm, incorporating both NGS and histologic results, that could correctly diagnose all the known MPLAs and IPMs. In particular, all IPMs identified by the refined algorithm were diagnosed to be IPMs or suspected IPMs by CHA reassessment. The refined algorithm-diagnosed MPLAs patients also had significantly better progression-free survival than the refined algorithm-diagnosed IPMs (p < 0.0001), which is superior to conventional NGS or CHA diagnoses. Overall, we developed an NGS-based algorithm that could accurately distinguish IPMs from MPLAs in MLA patients. Our results demonstrate a promising clinical utility of NGS to complement traditional CHA-based MLA diagnosis and help determine patient staging and treatment.

1153P Classification of multifocal lung adenocarcinomas subtypes using next-generation sequencing in pN0M0 lung adenocarcinomas

The incidence of multifocal lung adenocarcinomas (MLAs) increased remarkably over the past decade, owing to the advancement in imaging technology. The classification of MLAs subtypes, including multiple primary lung adenocarcinomas (MPLAs) and intrapulmonary metastases (IPMs), has great clinical significance in staging and treatment decisions. However, the application of molecular approaches in MLAs diagnosis, especially in pN0M0 patients, has not been well-investigated.

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.

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

BackgroundSynchronous multifocal lung cancer (SMLC) is diagnosed with increasing frequency in clinical practice globally. Due to innate variation in clinical management and outcome, it is vital to properly distinguish between synchronous multifocal primary lung cancer (SMPLC) and intrapulmonary metastasis (IM). The pathologic features and principal classification criteria of multifocal lung cancer remain unclear. Our objective was to evaluate the diagnostic value of histological morphologic features and driver gene mutations in SMLC classification.MethodsWe collected a unique cohort of Chinese patients with SMLC, and fully explored the morphologic, immunohistochemical, and molecular features of the disease. Twenty-one SMLC patients with a total of 50 tumours were included in our study. The pathological features that were presented by these patients were analysed, including the tumours location, tumours size, pathological types, predominant pattern of adenocarcinoma, and immunohistochemical staining. We conducted molecular testing of nine driver oncogenes that are associated with lung cancer, namely, EGER, KRAS, BRAF, NRAS, ALK, ROS1, RET, HER2, and PIK3CA.ResultsAccording to the Martini-Melamed classification and refined standard, 8 and 17 patients, respectively, were considered to have SMPLCs. Gene mutations were identified in 18 tumours (36%). Twelve patients had different gene mutations.ConclusionsWe demonstrate that conventional morphological assessment is not sufficient to clearly establish the clonal relationship of SMPLCs. Instead, the evaluation of histological subtypes, including nonmucinous adherent components, is required. Multiplex genotypic analysis may also prove to be a useful additional tool.

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

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

Major challenges in accurate mutation detection of multifocal lung adenocarcinoma by next-generation sequencing

ABSTRACTBackground: Many patients with advanced non-small cell lung cancer manifested with metastasis, and molecular heterogeneity may exhibit between primary and metastatic tumors. We sought to investigate the clinical detection strategy of primary and metastatic tumors in Chinese patients with NSCLC.Methods: Here, 77 paired tumors of Chinese patients with lung adenocarcinoma were analyzed, and 1836 mutation in hotspot regions of 22 genes were identified by next-generation sequencing. The expression of ALK in these paired tumors was also detected by immunohistochemistry.Results: The results showed that the concordance rate in multiple pulmonary nodules, primary-LN metastasis pairs and primary-distant metastasis pairs was 67.7%, 94.1% and 86.7%, respectively. In multiple pulmonary nodules, the concordance rate was 100% when the pathologic diagnosis was intrapulmonary metastasis, whereas the concordance rate was 23.1% when the pathologic diagnosis was multiple primary tumors. TP53 and CTNNB1 mutations were detected as the recurrent alterations in LN metastasis. Moreover, the concordance of ALK status was observed in these pairs.Conclusions: Our data suggested that hotspot mutations and ALK status in the primary-metastasis pairs had a high concordance in lung adenocarcinoma. Clinical detection of one lesion may be enough to identify the key alterations except that patients are diagnosed with multiple primary tumors or have disease progression after benefiting from target therapy.

Abstract 582: Tumor immunoediting in a lung cancer mouse model harboring EGFR mutations

Abstract Background: Anti-Programed cell death 1 (PD-1) antibodies such as nivolumab or pembrolizumab show promising treatment effects in smoking-related lung cancer. However, anti-PD-1 antibodies have very little effect on epidermal growth factor receptor (EGFR) mutant non-small cell lung cancer (NSCLC). EGFR mutations are the most frequent oncogenic drivers in non-smoking related NSCLC. Therefore, we aimed to explore the mechanism underlying tumor immunoediting in a lung cancer mouse model harboring EGFR mutations. Methods: We previously established two strains of transgenic lung cancer mouse (C57BL/6) harboring a mouse Egfr exon 19-deletion (mDEL) or a human EGFR L858R (hLR) mutation, driven by a surfactant protein (SP)-C promoter (Ohashi, Cancer Sci. 2008; Ohashi, Cancer Res. 2009). These mice developed EGFR-dependent multifocal lung adenocarcinomas from type II pneumocytes. We modified the two models by transplanting lung tumors subcutaneously into C57BL/6 (Ohashi, AACR. 2018). Evaluation of mice tumor lymphocyte profile was done through flow cytometry or immunohistochemistry (IHC). Effects of T cell depletion or anti-mouse PD-1 antibody (4H2) in vivo were also assessed. Comprehensive analysis of mRNA expression of immuno-checkpoint molecules in the tumors was performed using PanCancer Immune Profiling Panel (NanoString Technologies). Results: CD4+ T cells and/or CD8+ T cells were depleted in the subcutaneously transplanted tumor model followed by treatment with gefitinib (50 mg/kg/day, 5 days/week) for 2 weeks. As a result, after gefitinib discontinuation, rapid regrowth was seen in the tumors from groups with depletion of CD8+ T cells; depletion of CD4+ T cells had little effect on tumor regrowth, and tumor inhibition continued for 2 weeks after cessation of gefitinib. IHC showed relatively increased numbers of CD4+ T cells in the mice tumors whereas a decrease in the number of CD8+ T cells or Foxp3 positive cells was noted. PD-L1 expression was not observed in the tumors. Consistently, 4H2 showed little effect on tumor growth in vivo. The cancer immune panel showed increased expression of immune mediators such as Ccl6, Clec4n, and Lcn2. Conclusions: Our results suggest that CD8+ T cells can recognize mice tumors in vivo. New immuno-checkpoint molecules regulating CD8+ T cells from PanCancer Immune Profiling Panel were evaluated. Further, we plan to evaluate the efficacy of various immuno-checkpoint inhibitors in vivo. Citation Format: Kazuya Nishii, Kadoaki Ohashi, Kiichiro Ninomiya, Go Makimoto, Hiromi Watanabe, Hirohisa Kano, Naofumi Hara, Heiichiro Udono, Katsuyuki Kiura. Tumor immunoediting in a lung cancer mouse model harboring EGFR mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 582.

Concomitant EGFR Mutation and EML4-ALK Rearrangement in Lung Adenocarcinoma Is More Frequent in Multifocal Lesions

BackgroundThe coexistence of epidermal growth factor receptor (EGFR) mutation and anaplastic lymphoma kinase (ALK) rearrangement in patients with multifocal lung adenocarcinomas (LUAC) constitutes a rare molecular subtype of lung cancer. We aimed to investigate the intertumoral heterogeneity of pathologic and genetic characteristics of multifocal LUAC with EGFR/ALK co-alterations. Patients and MethodsA total of 1059 LUAC patients who underwent resection were investigated to screen for EGFR or ALK alterations using amplification refractory mutation system polymerase chain reaction and immunohistochemistry/fluorescence in situ hybridization. Molecular testing was extensively performed in patients with synchronous multifocal LUAC. Clonal evolution analysis was implemented using next-generation sequencing. ResultsA total of 97 multiple synchronous lesions were observed among 1059 LUAC patients. Patients with at least 1 sample harboring EGFR mutation or ALK rearrangement were 62.89% (61/97) and 14.43% (14/97), respectively. Patients with concomitant EGFR and ALK alterations were 4.71% (4/97). Comparatively, patients with unifocal LUAC harboring EGFR mutation, ALK rearrangement, and EGFR/ALK co-alterations were 58.25% (570/962), 6.44% (62/962), and 0.83% (8/962), respectively. The prevalence of EGFR/ALK co-alterations in the multifocal LUAC was significantly higher than that in the unifocal LUAC (4.71% (4/97) vs. 0.83% (8/962)). Furthermore, we present 4 cases of EGFR/ALK co-altered multifocal LUAC with different morphological and molecular patterns. In addition to radiographic, pathological, and molecular testing results, clonal evolutional analysis could also be used to distinguish intertumoral heterogeneity. ConclusionThe results highlight the importance of distinguishing synchronous primary tumors from intrapulmonary metastases, and of assessing the relative abundance of EGFR mutation and ALK rearrangement in patients with multifocal adenocarcinomas with EGFR/ALK co-alterations.

Applying comprehensive histologic assessment and genetic testing to synchronous multifocal lung adenocarcinomas and further survival analysis.

Applying comprehensive histologic assessment and genetic testing to synchronous multifocal lung adenocarcinomas and further survival analysis.

Clonality assessment of multifocal lung adenocarcinoma by pathology evaluation and molecular analysis

The aim of this study was to explore morphologic and molecular features distinguishing between multifocal lung adenocarcinoma (MLA) and intrapulmonary metastases (IMs). Sixteen patients with MLAs, a total of 34 tumors, were reviewed. Four approaches were used: (1) array-comparative genomic hybridization (CGH) as a standard clonality assessment; (2) EGFR and KRAS mutational profiles as a supplementary method; (3) comprehensive histologic assessment (CHA) was method I in pathology evaluation; and (4) CHA combined with lepidic component analysis was method II. The lepidic component was divided into low grade and high grade according to extent of atypia; tumors with low-grade lepidic component were defined as primary. Eight patients were found to have IMs and 8 to have multiple primaries (MPs) by array-CGH; 7 had MPs and 9 had IMs by method I; 5 had MPs and 11 had IMs by method II. Compared with array-CGH, method I had a lower coincidence rate (65%) than method II (85%). Univariate analysis revealed that patients with MP had a better clinical outcome than those with IM only if the MPs were diagnosed by array-CGH (P = .034) or method II (P = .027) but not EGFR/KRAS mutation (P = .843) or method I (P = .493). Our results suggest that a low-grade lepidic component is a sign of a primary tumor. CHA combined with a low-grade lepidic component (method II) is more accurate clinically and more cost-effective in distinguishing MLAs from IMs. Also, EGFR mutation is not an appropriate molecular marker for clonality assessment.

Subjecting appropriate lung adenocarcinoma samples to next-generation sequencing-based molecular testing: challenges and possible solutions.

Next‐generation sequencing (NGS) has recently been rapidly adopted in the molecular diagnosis of cancer, but it still faces some obstacles. In this study, 665 lung adenocarcinoma samples (558 TKI‐naive and 107 TKI‐relapsed samples) were interrogated using NGS, and the challenges and possible solutions of subjecting appropriate tissue samples to NGS testing were explored. The results showed that lower frequencies of HER2/BRAF/PIK3CA and acquired EGFR T790M mutations were observed in biopsy samples with <20% tumor cellularity than in those with ≥20%, but there were no significant differences in the frequencies of EGFR or KRAS mutations. Moreover, tumor heterogeneity was assessed by heterogeneity score (HS), which was calculated through multiplying by 2 the mutant allele frequency (MAF) of tumor cells. In TKI‐naive samples, intratumor heterogeneity could occur in EGFR,KRAS,HER2,BRAF, and PIK3CA mutant tumors, but the degree was variable. Higher EGFR, but lower BRAF and PIK3CA HS values were observed compared with KRAS HS. In TKI‐relapsed samples, analysis of concomitant sensitizing EGFR and T790M MAFs showed that intratumor heterogeneity was common in acquired EGFR T790M mutant tumors. The mutational status between primary and metastatic tumors was usually concordant, but KRAS,HER2, and PIK3CA HS were significantly higher in metastatic tumors than in primary tumors. Additionally, the discordance rate of mutational status in multifocal lung adenocarcinomas diagnosed as equivocal or multiple primary tumors was high. Together, our findings demonstrate that a comprehensive quality assessment is necessary during tissue process to mitigate the challenges of poor tumor cellularity, tumor heterogeneity, and multifocal clonally independent tumors.

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.

Next-Generation Sequencing: A Novel Approach to Distinguish Multifocal Primary Lung Adenocarcinomas from Intrapulmonary Metastases

Distinguishing between multiple lung primary tumors and intrapulmonary metastases is imperative for accurate staging. The American Joint Committee on Cancer (AJCC) criteria are routinely used for this purpose but can yield equivocal conclusions. This study evaluated whether next-generation sequencing (NGS) using the 50-gene AmpliSeq Cancer Hotspot Panel version 2 can help facilitate this distinction. NGS was performed on known primary-metastatic pairs (8 patients) and multiple lung adenocarcinomas (11 patients). Primary-metastatic pairs had high mutational concordance. Seven pairs shared mutations, and 1 was concordant for having no mutations. Driver mutations in KRAS (n = 4), EGFR (n = 2), and BRAF (n = 1) were always concordant. Multiple lung tumors from 3 patients were completely concordant and predicted by NGS to be intrapulmonary metastases, whereas 8 had completely discordant mutations and were predicted to be independent primary tumors. The NGS prediction correlated with the AJCC (eighth edition) prediction in all patients for whom the latter was unequivocal (8 of 11). Furthermore, it separated patients by overall survival. Patients with predicted multiple independent primary tumors by NGS had better survival than those with distant metastases (P=0.016, log-rank test), whereas those with predicted intrapulmonary metastases had no difference (P=0.527). With further validation, the 50-gene panel has the potential to serve as an adjunct to the AJCC criteria.

P1.02-040 Heterogeneity of the EGFR / KRAS Gene Mutation in Multifocal Lung Adenocarcinoma and the Clinical Significance

Significant advances on EGFR-targeted therapy have allowed increasing availability of therapeutic options for non-small cell lung cancers. For multifocal lung adenocarcinoma patients in clinic, the EGFR gene mutation is generally examined only on the largest tumor or the one containing the most tumor cells, which could omit the tumors harboring the EGFR mutation and thus loss of opportunity for the tyrosine kinase inhibitors therapy. A total of 58 cases of multifocal lung adenocarcinoma, including 129 intrapulmonary tumors resected surgically, was recruited for this study. The genome DNA samples were prepared from formalin-fixed and paraffin-embedded tumor tissues. The EGFR / KRAS mutational status of each tumor was examined by Sanger’s DNA sequencing. The targeted hotspot mutations in EGFR gene included p.G719S/C/A (exon 18), p.T790M (exon 20), p.S768I (exon 20), p.L858R (exon 21), p.L861Q (exon 21) and deletions in exon 19. The hotspot mutations in KRAS gene were within codon 12 including p.G12C/V/S/R/D/A. In this group of 58 patients with multifocal lung adenocarcinoma, 38 patients were found EGFR or KRAS mutations in their tumors. Among them, the EGFR mutations were detected in 59 tumors derived from 34 cases; while the KRAS mutations were detected in 7 tumors from 5 cases. One patient (Case 30) was identified EGFR (exon 18, p.G719A) or KRAS (p.G12A or p.G12C) mutation in her 3 tumors, respectively. It is noteworthy that there were 21 (36.2%) in the 58 cases showing the mutational heterogeneity among the multiple intrapulmonary tumors derived from one individual, and that 6 tumors harbored 2 different types of EGFR mutation. However, none of the specimens investigated contained both EGFR and KRAS mutations within a same tumor. Comparing data from the present study along with the molecular pathological diagnosis records from the Department of Pathology, among the 58 cases enrolled, 30 cases accepted routine molecular pathological examination to check the EGFR / KRAS mutation, and 28 cases did not. However, 37 out of 66 tumors from the 30 cases were tested -- only 5 patients had all their tumors examined; whereas in the rest total 92 tumors unchecked, 42 EGFR sensitive mutations were identified in this study. Current finding suggests that the EGFR and KRAS mutational heterogeneity is widely existed in multifocal lung adenocarcinomas. Therefore, reliable and exhaustive examination for EGFR/KRAS mutation should be executed in the every tumor, to provide more individualized therapy choices for the patients.

SC02.02 Surgical Choices for Patients with Multifocal Lung Cancer

SC02.02 Surgical Choices for Patients with Multifocal Lung Cancer