Redoxhigh phenotype mediated by KEAP1/STK11/SMARCA4/NRF2 mutations diminishes tissue-resident memory CD8+ T cells and attenuates the efficacy of immunotherapy in lung adenocarcinoma.

Metabolism reprogramming within the tumor microenvironment (TME) can have a profound impact on immune cells. Identifying the association between metabolic phenotypes and immune cells in lung adenocarcinoma (LUAD) may reveal mechanisms of resistance to immune checkpoint inhibitors (ICIs). Metabolic phenotypes were classified by expression of metabolic genes. Somatic mutations and transcriptomic features were compared across the different metabolic phenotypes. The metabolic phenotype of LUAD is predominantly determined by reductase-oxidative activity and is divided into two categories: redoxhigh LUAD and redoxlow LUAD. Genetically, redoxhigh LUAD is mainly driven by mutations in KEAP1, STK11, NRF2, or SMARCA4. These mutations are more prevalent in redoxhigh LUAD (72.5%) compared to redoxlow LUAD (17.4%), whereas EGFR mutations are more common in redoxlow LUAD (19.0% vs. 0.7%). Single-cell RNA profiling of pre-treatment and post-treatment samples from patients receiving neoadjuvant chemoimmunotherapy revealed that tissue-resident memory CD8+ T cells are responders to ICIs. However, these cells are significantly reduced in redoxhigh LUAD. The redoxhigh phenotype is primarily attributed to tumor cells and is positively associated with mTORC1 signaling. LUAD with the redoxhigh phenotype demonstrates a lower response rate (39.1% vs. 70.8%, p = 0.001), shorter progression-free survival (3.3 vs. 14.6 months, p = 0.004), and overall survival (12.1 vs. 31.2 months, p = 0.022) when treated with ICIs. The redoxhigh phenotype in LUAD is predominantly driven by mutations in KEAP1, STK11, NRF2, and SMARCA4. This phenotype diminishes the number of tissue-resident memory CD8+ T cells and attenuates the efficacy of ICIs.

Allelic Context of EGFR C797X-Mutant Lung Cancer Defines Four Subtypes With Heterogeneous Genomic Landscape and Distinct Clinical Outcomes.

INTRODUCTION: EGFR C797X (C797S or C797G) mutation is the most frequent on-target mechanism of resistance to osimertinib. The hypothesis that the allelic context of C797X/T790M has implications for treatment is on the basis of sporadic reports and needs validation with larger cohorts. METHODS: We identified patients with EGFR C797X-mutant NSCLC from nine centers who progressed on osimertinib, all analyzed in a single laboratory through next-generation sequencing. We analyzed genomic profiles and assessed associations between clinical outcomes and C797X status. RESULTS: A total of 365 EGFR C797X-mutant cases were categorized into four subtypes on the basis of allelic context: in cis (75.3%), in trans (6.4%), cis&trans (10.4%), and C797X-only (7.9%). Genomically, the cis&trans subtype displayed the highest frequency of concurrent alterations at osimertinib resistance sites (21.1%), while the in cis subtype had the lowest (8.4%). Clinically, cis&trans patients exhibited the worst progression-free survival (PFS) on both previous (median 7.7 mo) and subsequent treatment (median 1.0 mo) and overall survival (median 3.9 mo). In subsequent treatments, in cis patients exhibited superior PFS with combined brigatinib and cetuximab (median 11.0 mo) compared with other regimens (p = 0.005), while in trans patients exhibited variable outcomes with combined first or second- and third-generation EGFR inhibitor (PFS range: 0.7-8.1 mo, median 2.6 mo). Notably, subtype switching was observed after subsequent treatments, predominantly toward the in cis subtype. CONCLUSIONS: Allelic context could define four EGFR C797X-mutant NSCLC subtypes with heterogeneous genetic landscapes and distinct clinical outcomes. Subsequent treatments further complicate the scenario through subtype switching.

Efficacy, safety and dose selection of AZD3759 in patients with untreated EGFR-mutated non-small-cell lung cancer and central nervous system metastases in China (CTONG1702-Arm 8): a multi-center, single-arm, phase 2 trial.

Background: Central nervous system (CNS) metastases is inevitable for epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC). AZD3759 is a novel EGFR-TKI with impressive CNS penetration. Methods: We initiated a phase 2, multi-center, umbrella trial (CTONG1702, NCT03574402). The eighth arm assessed the efficacy and safety of AZD3759 in untreated EGFR-mutated NSCLC with CNS metastases. The primary objective was the objective response rate (ORR). Simon's minimax two-stage design was used to calculate the sample size. Dose optimal selection was performed using 200- and 300-mg bid cohorts. Findings: Between Oct 18, 2018 and Sep 14, 2020, 30 patients received AZD3759 at 200 mg (n = 15) or 300 mg (n = 15) bid. At data cutoff (Dec 31, 2022), median follow-up was 35.4 months. The primary endpoint was reached, with a confirmed ORR of 70% (21/30) (200 mg, 80%; 300 mg, 60%). The median progression-free survival was 12.9 months (200 mg, 15.8 months; 300 mg, 10.7 months). Grade 3 or 4 treatment-related adverse events occurred in 73% (22/30) of the patients (200 mg: 60%; 300 mg: 87%). 59% (10/17) of the patients developed a T790M mutation at disease progression. The median overall survival was 33.7 months, and 34.1 months and 25.3 months in patient treated with or without osimertinib in a later-line setting, respectively. Interpretation: AZD3759 showed promising efficacy and tolerable safety as a first-line therapy in EGFR-mutated NSCLC with CNS metastases. The 200-mg bid cohort had better clinical outcomes. Sequential use of AZD3759 and third-generation EGFR-TKIs represents a new option. Funding: Chinese Thoracic Oncology Group (CTONG).

Immune suppressive microenvironment in liver metastases contributes to organ-specific response of immunotherapy in advanced non-small cell lung cancer.

BACKGROUND: The liver is a frequent site of metastases and liver metastases (LM) correlate with diminished immunotherapy efficacy in non-small cell lung cancer (NSCLC). This study aimed to analyze whether tumor response to immunotherapy differs between pulmonary lesions (PL) and LM in NSCLC and to explore potential mechanisms through multiomics analysis. METHODS: This observational longitudinal clinical cohort study included patients with NSCLC with LM receiving immunotherapy was conducted to evaluate organ-specific tumor response of PL and LM. We collected paired PL and LM tumor samples to analyze the organ-specific difference using whole-exome sequencing, RNA sequencing, and multiplex immunohistochemistry. RESULTS: A total of 52 patients with NSCLC with LM were enrolled to evaluate the organ-specific response of immunotherapy. The objective response rate (21.1% vs 32.7%) and disease control rate of LM were lower than that of PL (67.3% vs 86.5%). One-third of patients showed mixed response, among whom 88.2% (15/17) presented with LM increasing, but PL decreasing, while the others had the opposite pattern (p=0.002). In another independent cohort, 27 pairs of matched PL and LM tumor samples from the same individuals, including six simultaneously collected pairs, were included in the translational part. Genomic landscapes profiling revealed similar somatic mutations, tumor mutational burden, and neoantigen number between PL and LM. Bulk-RNA sequencing showed immune activation-related genes including CD8A, LCK, and ICOS were downregulated in LM. The antigen processing and presentation, natural killer (NK) cell-mediated cytotoxicity and T-cell receptor signaling pathway were enriched in PL compared with LM. Multiplex immunohistochemistry detected significantly lower fractions of CD8+ cells (p=0.036) and CD56dim+ cells (p=0.016) in LM compared with PL. Single-cell RNA sequencing also characterized lower effector CD8+ T cells activation and NK cells cytotoxicity in LM. CONCLUSIONS: Compared with PL, LM presents an inferior organ-specific tumor response to immunotherapy. PL and LM showed limited heterogeneity in the genomic landscape, while the LM tumor microenvironment displayed lower levels of immune activation and infiltration than PL, which might contribute to developing precise immunotherapy strategies for patients with NSCLC with LM.

First-line pyrotinib in advanced HER2-mutant non-small-cell lung cancer: a patient-centric phase 2 trial.

To explore targeted treatment options in patients with non-small-cell lung cancer (NSCLC) with rare genetic mutations in the context of a patient-centric clinical trial, we initiated, in parallel, a phase 2 adaptive umbrella trial consisting of a criteria-fulfilled (CF) cohort and a compassionate use (CU) cohort under expanded eligibility criteria, and a prospective real-world study (RWS). Here, we present efficacy and safety data from 48 patients with treatment-naive, advanced HER2-mutant NSCLC treated with the pan-HER receptor tyrosine kinase inhibitor pyrotinib (CF and CU cohorts) or physician's therapy of choice (RWS cohort). In the phase 2 trial CF cohort (n = 28), the primary endpoint was reached with an objective response rate of 35.7% after pyrotinib treatment. Secondary endpoints included disease control rate (89.3%), median progression-free survival (PFS) (7.3 months), median overall survival (OS) (14.3 months) and toxicity, which was acceptable, with grade 3 or 4 treatment-related adverse events occurring in three patients (10.7%). The phase 2 trial CU cohort (n = 12) showed an objective response rate of 16.7%, disease control rate of 83.4%, median PFS of 4.7 months and median OS of 14.2 months after pyrotinib treatment. The RWS cohort (n = 8) had no responses to physician's therapy of choice, while median PFS and OS were 3.0 and 12.2 months, respectively. Phase 2 umbrella trial, clinicaltrials.gov identifier: NCT03574402 . RWS, clinicaltrials.gov identifier: NCT03605602 .

Selective RET inhibitors shift the treatment pattern of RET fusion-positive NSCLC and improve survival outcomes.

PURPOSE: Rearranged during transfection (RET) fusions are important genetic drivers in non-small cell lung cancer (NSCLC). Selective RET inhibitors are setting a new paradigm in RET-driven NSCLC. However, the real-world treatment patterns, outcomes and toxicity remain largely unknown. METHODS: Data from RET fusion-positive NSCLC patients treated in our centre were retrospectively analysed. Of them, patients diagnosed before and after August 2018 were included in analysis of treatment patterns; and patients received selective RET inhibitors were eligible for analysis of adverse events (AEs). RESULTS: Patients diagnosed before August 2018 (n = 30) predominantly received chemotherapy and immunotherapy (83%) as initial therapy, while patients diagnosed after August 2018 (n = 39) mainly received selective RET inhibitors (38.5% at first-line; 50.0% at second-line). In the total 69 patients, overall survival (OS) was prolonged in patients treated with selective RET inhibitors versus untreated patients (median 34.3 versus 17.5 months; p = 0.002) during a median follow-up of 28.7 months. But there was no difference between patients treated with immunotherapy versus untreated patients. In the 38 patients received selective RET inhibition, median progression-free survival (PFS) was 11.9 months. AEs ≥ grade 3 occurred in 42.1% patients and were not associated with PFS (p = 0.63) or OS (p = 0.60). Haematological toxicity ≥ grade 3 occurred in 31.6% patients and was the leading cause of drug discontinuation. CONCLUSION: Selective RET inhibitors are increasingly being adopted into clinical practice and are associated with improved OS. However, treatment-related ≥ grade 3 AEs, especially haematologic AEs, occur frequently in real-world setting.

Characteristics of and Treatment Strategies for Advanced EGFR-Mutant NSCLC With Concomitant BRAF Variations.

Introduction: BRAF variants were reported resistant mechanisms to EGFR tyrosine kinase inhibitors (TKIs) in EGFR-mutant NSCLC. Nevertheless, characteristics and subsequent treatment strategies of such patients remain unclear. Methods: From October 2016 to May 2020, patients with advanced NSCLC for whom next-generation sequencing detected mutations of both BRAF and EGFR were retrospectively included. From June 2020 to January 2021, patients with EGFR-mutant NSCLC who acquired the BRAF V600E mutation after progression on osimertinib were prospectively enrolled to explore the efficacy and safety of EGFR plus BARF co-inhibition. Results: A total of 58 patients were retrospectively identified and five prospectively included. BRAF variants were acquired after a median time of 22.7 months from initial diagnosis. The frequency of variations in TP53, PIK3CA, RB1, MET, LRP1B, APC, CDKN2A, MYC, ERBB2, and SMAD4 was all more than 10%; these mutations affected the cell cycle or p53 pathway and the EGFR downstream and bypass pathways. The median progression-free survival was 5.0 months for patients on chemotherapy and 2.1 months for those on TKIs not targeting both of EGFR and BRAF (p = 0.019). The median PFS was 7.8 months in five patients who received EGFR plus BRAF co-inhibitory drugs. RAS signaling was activated on disease progression. Conclusions: Variations in the EGFR downstream and bypass pathways were frequent in patients with dual mutations of EGFR and BRAF. The efficacies of TKIs not targeting both EGFR and BRAF were inferior to chemotherapy. EGFR plus BRAF co-inhibition improved efficacy. Such treatment strategies should be further explored.

Biomarker-Driven Studies With Multi-targets and Multi-drugs by Next-Generation Sequencing for Patients With Non-Small-Cell Lung Cancer: An Open-Label, Multi-center, Phase II Adaptive Umbrella Trial and a Real-World Observational Study (CTONG1702&CTONG1705).

BACKGROUND: With rare genetic variations having been increasingly recognized at a preclinical stage, a variety of early-phase clinical trials have been launched. Due to the low incidence rate of these variations, although the sample size of trials are small, it still needs a large number of patients for screening. With the advent of next-generation sequencing (NGS), multiple genetic variations can be detected simultaneously. Multiple biomarkers and agents can be evaluated using umbrella clinical trials, which rapidly and effectively screen and enroll patients for parallel sub-studies using NGS. PATIENTS AND METHODS: We designed an open-label, multi-center, phase II clinical trial CTONG1702. This is an adaptive umbrella trial that will evaluate the efficacy and safety of several biomarker-driven agents, including tyrosine kinase inhibitors (TKIs) and a PD-1 inhibitor, in stage IIIB to IV patients (eighth AJCC) with non-small-cell lung cancer (NSCLC) patients. Patients will be enrolled in parallel sub-studies based on the results of NGS and PD-L1 IHC analysis. Patients who are not eligible for CTONG1702 will be enrolled in the observational real-world study CTONG1705. This study aims to develop a large-scale genomic database and explore the relationship between genetic variations in NSCLC patients and clinical outcomes. CONCLUSIONS: The adaptive umbrella trial will evaluate multi-targets and multi-drugs in advanced NSCLC patients (CTONG1702). In addition, the simultaneously initiated real-world study will provide additional data for clinical practice (CTONG1705).

Single-cell transcriptome analysis revealed a suppressive tumor immune microenvironment in EGFR mutant lung adenocarcinoma.

BACKGROUNDS: Immunotherapy is less effective in patients with epidermal growth factor receptor (EGFR) mutant non-small-cell lung cancer (NSCLC). Lower programmed cell death-ligand 1 (PD-L1) expression and tumor mutation burden (TMB) are reported to be the underlying mechanism. Being another important factor to affect the efficacy of immunotherapy, tumor microenvironment (TME) characteristics of this subgroup of NSCLC are not comprehensively understood up to date. Hence, we initiated this study to describe the specific TME of EGFR-mutant lung adenocarcinoma (LUAD) from cellular compositional and functional perspectives to better understand the immune landscape of this most common subtype of NSCLC. METHODS: We used single-cell transcriptome sequencing and multiplex immunohistochemistry to investigate the immune microenvironment of EGFR-mutant and EGFR wild-type LUADs and determined the efficacy of immunotherapy. We analyzed single cells from nine treatment-naïve samples and compared them to three post-immunotherapy samples previously reported from single cell perspective using bioinformatics methods. RESULTS: We found that EGFR-mutant malignant epithelial cells had similar characteristics to the epithelial cells in non-responders. EGFR-mutant LUAD lacked CD8+ tissue-resident memory (TRM) cells, which could promote tertiary lymphoid structure generation by secreting CXCL13. In addition, other cell types, including tumor-associated macrophages and cancer-associated fibroblasts, which are capable of recruiting, retaining, and expanding CD8+ TRM cells in the TME, were also deficient in EGFR-mutant LUAD. Furthermore, EGFR-mutant LUAD had significantly less crosstalk between T cells and other cell types via programmed cell death-1 (PD-1) and PD-L1 or other immune checkpoints compared with EGFR wild-type LUAD. CONCLUSIONS: Our findings provide a comprehensive understanding of the immune landscape of EGFR-mutant LUAD at the single-cell level. Based on the results, many cellular components might have negative impact on the specific TME of EGFR-mutant LUAD through influencing CD8+ TRM. Lack of CD8+ TRM might be a key factor responsible for the suppressive TME of EGFR-mutant LUAD.

Impact of EGFR amplification on survival of patients with EGFR exon 20 insertion-positive non-small cell lung cancer.

BACKGROUND: Epidermal growth factor receptor (EGFR) exon 20 insertion (EGFR ex20ins) is a common mutation in non-small cell lung cancer (NSCLC). Patients with EGFR ex20ins generally respond poor to EGFR-tyrosine kinase inhibitors (EGFR-TKIs). EGFR ex20ins are often co-occurring with EGFR amplification. However, the impact of EGFR amplification on the survival of patients with EGFR ex20ins mutations has not been determined. METHODS: This is an observational longitudinal cohort study. A prospectively managed database included consecutive treatment-naïve adult patients with advanced NSCLC and EGFR ex20ins confirmed by next-generation sequencing (NGS) at Guangdong Provincial People's Hospital between November 2017 and February 2019. The participants were enrolled from the database and extracted their clinical characteristics, treatment and clinical outcomes. NGS was used to establish whether EGFR amplification was present in tumor tissue. Overall survival (OS) and progression-free survival (PFS) were compared between EGFR amplification and non-EGFR amplification groups using the Kaplan-Meier method and log-rank test. Subgroup analyses were performed based on the treatment used (EGFR-TKI or chemotherapy). RESULTS: Fifteen different EGFR ex20ins mutation subtypes were identified in the 39 patients included in the analysis, and the most common subtypes were p.A767_D770dup (25.6%), p.S768_D770dup (23.1%) and p.N771_H773dup (10.3%). Among 31 patients with EGFR ex20ins mutations and NGS data for tumor tissue, EGFR amplification was identified in 12 patients (38.7%) and there were no significant differences in clinical characteristics. Among 26 patients, there were no significant differences between the EGFR amplification (n=11) and non-EGFR amplification (n=15) groups in median OS (715 vs. 452 days, P=0.912). Among 20 patients administered chemotherapy, there were no significant differences between the EGFR amplification and non-EGFR amplification groups in median PFS (206 vs. 112 days, P=0.425). Among 24 patients administered an EGFR-TKI, median PFS was longer in the non-EGFR amplification group than in the EGFR amplification group (110 vs. 31 days, P=0.030). CONCLUSIONS: There is a tendency that EGFR amplification might be a poor predictor in EGFR ex20ins-positive NSCLC patients treated with EGFR-TKIs.

Mutational landscape and characteristics of ERBB2 in non-small cell lung cancer.

BACKGROUND: Tyrosine kinase domain (TKD) mutation and particularly exon 20 insertion mutations of ERBB2 have been extensively reported in non-small cell lung cancer (NSCLC). Due to the increased accessibility of next-generation sequencing, more ERBB2 mutations within the non-TKD can be detected in clinical practice. Nevertheless, the clinical significance of non-TKD mutations remains unknown. Hence, this study was designed to comprehensively outline the landscape and characteristics of ERBB2 mutations in NSCLC. METHODS: A total of 1934 patients with NSCLC from cBioPortal were included in the study. An ERBB2 mutation cohort was identified, while subsequent analyses revealed clinical and genomic characteristics. RESULTS: The frequency of ERBB2 mutation was 4.5%, and it was determined to be more likely to occur in never-smokers. ERBB2 mutations occurring in the non-TKD accounted for 57.5% of ERBB2 mutations. In the non-TKD, missense mutation was the most recurrent mutation type, and S310F was the most recurrent mutation variant. ERBB2 mutations within non-TKD also had a strong oncogenic ability where up to 37.5% of ERBB2 oncogenic mutations were within non-TKD. The co-mutation of EGFR or KRAS was higher in the non-TKD mutation compared to the TKD mutation. Shorter overall survival was observed in ERBB2-mutant patients compared with ERBB2 wild-type patients. There was no significant difference in overall survival between patients with non-TKD mutations and TKD mutations. CONCLUSIONS: The present study showed that a considerable portion of non-TKD mutations were oncogenic. ERBB2 mutation was a poor prognostic factor. The non-TKD mutation might also be used as a therapeutic target in ERBB2-directed target therapy. KEY POINTS: • Significant findings of the study ERBB2 mutations were more abundant within a nontyrosine domain than those within the tyrosine domain. Up to 37.5% of ERBB2 oncogenic mutations were within the nontyrosine domain. ERBB2 mutation was a poor prognostic factor. • What this study adds The frequency of EGFR or KRAS co-mutations were significantly higher in ERBB2 mutations within the nontyrosine kinase domain compared to ERBB2 mutations within the tyrosine kinase domain. Nontyrosine domain mutations confer equal overall survival to tyrosine domain mutations.

Benign disease prone to be misdiagnosed as malignant pulmonary nodules: Minute meningothelioid nodules.

BACKGROUND: The lung is one of the most common target organs for malignant tumor metastasis. The existence of lung metastasis may have a decisive effect on the choice of treatment regimen. Minute pulmonary meningothelial-like nodules (MPMNs) usually present as ground-glass opacity or solid nodules, mimicking the imaging findings of malignant pulmonary nodules. This study summarizes the clinical, radiological, and pathological features of MPMNs to distinguish them from malignant pulmonary nodules. METHODS: The Guangdong Lung Cancer Institute Pathology Information System was searched using the key words "minute meningothelioid nodules" and "lung." Patients who underwent pulmonary resection from 23 February 2009 to 31 May 2017 were included in the study. The 11th edition of Rosai and Ackerman's Surgical Pathology was used to confirm the diagnosis. The clinical, imaging, and pathological characteristics of MPMNs were recorded. RESULTS: Twelve patients had MPMNs. MPMNs were associated with cancerous or precancerous lesions (10/12), female gender (11/12), and non-smokers (11/12). Four patients were misdiagnosed with malignant pulmonary nodules before surgery. Positron emission tomography-computed tomography revealed an increased maximum standardized uptake value in one patient. Immunohistochemistry identified eight specimens positive for vimentin, EMA, and PR and negative for TTF-1 and CK. CONCLUSIONS: MPMNs tend to coexist with malignant tumors, mimicking the imaging findings of malignant pulmonary nodules, thus resulting in misdiagnosis. Dynamic monitoring or an invasive examination may help to distinguish MPMNs from malignant lesions.

Analysis of Genetic Screening in Couples of Reproductive Age for Thalassemia in Lingshui Li Autonomous County of Hainan Province / 中国实验血液学杂志

OBJECTIVE@#To investigate the genetic carrier rate of thalassemia and its gene mutation types as well as the distribution characteristics among the people in Lingshui Li autonomous county of Hainan province, so as to provide the basis for making the prevention programs of thalassemia in administrative departments.@*METHODS@#Samples were collected from couples undergoing premarital and pregestational screenings, in which the positive ones in preliminary screening were further tested by genetic diagnoses and the genotypes were analyzed.@*RESULTS@#The rate of thalassemia gene carriers was 19.41% （274/1412） of the couples of childbearing age in Lingshui Li autonomous County of Hainan Province. In these carriers,α-thalassemia accounted for 83.21%（228/274）, β-thalassemia for 8.03%（22/274）, and both α-and β-thalassemia gene accounted for 8.76% （28/274）.@*CONCLUSION@#The carrying rate of thalassemia gene in population Lingshui Li autonomous county of Hainan province is high, and its distribution has geographical characteristics,the major type is α-thalassemia. Blood screening and genetic diagnosis of thalassemia should be strengthened, and corresponding measures should be taken to reduce its gene frequency.

EGFR mutations in early-stage and advanced-stage lung adenocarcinoma: Analysis based on large-scale data from China.

BACKGROUND: EGFR-tyrosine kinase inhibitors play an important role in the treatment of advanced non-small cell lung cancer (NSCLC). EGFR mutations in advanced NSCLC occur in approximately 35% of Asian patients and 60% of patients with adenocarcinoma. However, the frequency and type of EGFR mutations in early-stage lung adenocarcinoma remain unclear. METHODS: We retrospectively collected data on patients diagnosed with lung adenocarcinoma tested for EGFR mutation. Early stage was defined as pathological stage IA-IIIA after radical lung cancer surgery, and advanced stage was defined as clinical stage IIIB without the opportunity for curative treatment or stage IV according to the American Joint Committee on Cancer Staging Manual, 7th edition. RESULTS: A total of 1699 patients were enrolled in this study from May 2014 to May 2016; 750 were assigned to the early-stage and 949 to the advanced-stage group. Baseline characteristics of the two groups were balanced, except that there were more smokers in the advanced-stage group (P < 0.001). The total EGFR mutation rate in the early-stage group was similar to that in the advanced-stage group (53.6% vs. 51.4%, respectively; P = 0.379). There was no significant difference in EGFR mutation type between the two groups. In subgroup analysis of smoking history, there was no difference in EGFR mutation frequency or type between the early-stage and advanced-stage groups. CONCLUSION: Early-stage and advanced-stage groups exhibited the same EGFR mutation frequencies and types.