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Circulating tumor DNA (ctDNA) is DNA fragment shed from tumor cells and can be isolated from peripheral blood. ctDNA carries genomic information of cancer and is the most widely utilized indicator in liquid biopsy. The application of ctDNA is gaining traction due to its reproducible, non-invasive, and easy-to-obtain characteristics. With the development of detection approaches, ctDNA plays an important role in the management of patients with cancers. In this review, we summarize the basic ctDNA detection measurements and review its application in early screening, prognosis evaluation after the surgery, and efficacy prediction of different therapies in non-small cell lung cancer.

In the clinical treatment of lung cancer, therapy failure is mainly caused by cancer metastasis and drug resistance. Here, we investigated whether the tyrosine phosphatase Shp2 is involved in the development of metastasis and drug resistance in non-small cell lung cancer (NSCLC). Shp2 was overexpressed in a subset of lung cancer tissues, and Shp2 knockdown in lung cancer cells inhibited cell proliferation and migration, downregulated c-Myc and fibronectin expression, and upregulated E-cadherin expression. In H1975 cells, which carry double mutations (L858R + T790M) in epidermal growth factor receptor (EGFR) that confers resistance toward the tyrosine kinase inhibitor gefitinib, Shp2 knockdown increased cellular sensitivity to gefitinib; conversely, in H292 cells, which express wild-type EGFR and are sensitive to gefitinib, Shp2 overexpression increased cellular resistance to gefitinib. Moreover, by overexpressing Shp2 or using U0126, a small-molecule inhibitor of extracellular signal-regulated kinase 1/2 (ERK1/2), we demonstrated that Shp2 inhibited E-cadherin expression and enhanced the expression of fibronectin and c-Myc through activation of the ERK1/2 pathway. Our findings reveal that Shp2 is overexpressed in clinical samples of NSCLC and that Shp2 knockdown reduces the proliferation and migration of lung cancer cells, and further suggest that co-inhibition of EGFR and Shp2 is an effective approach for overcoming EGFR T790M mutation acquired resistance to EGFR tyrosine kinase inhibitors (TKIs). Thus, we propose that Shp2 could serve as a new biomarker in the treatment of NSCLC.

Lung cancer is one of the most common cancers and the predominant cause of cancer‐related death in the world. The low accuracy of early detection techniques and high risk of relapse greatly contribute to poor prognosis. An accurate clinical tool that can assist in diagnosis and surveillance is urgently needed. Circulating tumor DNA (ctDNA) is free DNA shed from tumor cells and isolated from peripheral blood. The genomic profiles of ctDNA have been shown to closely match those of the corresponding tumors. With the development of approaches with high sensitivity and specificity, ctDNA plays a vital role in the management of lung cancer as a result of its reproducible, non‐invasive, and easy‐to‐obtain characteristics. However, most previous studies have focused on advanced lung cancer. Few studies have investigated ctDNA in the early stages of the disease. In this review, we focus on ctDNA obtained from patients in the early stage of lung cancer, provide a summary of the related literature to date, and describe the main approaches to ctDNA and the clinical applications.

The combination of cisplatin and vinorelbine is an evidence-supported regimen for adjuvant chemotherapy for treating non-small cell lung cancer (NSCLC). But this doublet has considerable toxicity and unfavorable tolerability, and results in poor compliance. The cisplatin and gemcitabine regimen is one of the most active and well-tolerated regimens against advanced NSCLC, but its toxicity and tolerability has not been adequately evaluated in the adjuvant setting.From a lung cancer database we retrospectively reviewed NSCLC patients receiving adjuvant chemotherapy of cisplatin (75 mg/m(2)) and gemcitabine (1250 mg/m(2)) between January 2005 and December 2011. Postoperative demographics, compliance to adjuvant therapy and toxicity were retrieved from medical records.A total of 132 patients met the criteria and were included in the study, 96 were male (72.7%) and 36 were female (27.3%). Median age was 60.5 years old, range 29 - 75 years, and 41.7% of patients were ≥ 65 years old. Overall, 68.2% patients received all four planned cycles, and the cumulative dose delivered for gemcitabine was 8333 mg (83.3% of the planned dose) and cisplatin 248 mg (82.7% of the planned dose). There were no treatment-related deaths. Grade 3/4 neutropenia developed in 47 patients (35.6%) and was the predominant hematologic toxicity. Common grade 3/4 non-hematologic toxicities were nausea/vomiting (22.0%), infection (12.3%), and febrile neutropenia (11.4%).Cisplatin and gemcitabine are feasible for use in the adjuvant setting with a favorable toxicity profile and superior tolerability compared with published data on cisplatin and vinorelbine.

Mediastinal lesions are often difficult to diagnose in clinical practice because of the unique anatomical position of the mediastinum, which makes performance of biopsy difficult. The value of endobronchial ultrasound-guided transbronchial needle aspiration in the diagnosis of lung cancer and mediastinal lymph node staging has been widely accepted. However, few studies have been conducted on the value of endobronchial ultrasound-guided transbronchial needle aspiration in the diagnosis and differential diagnosis of mediastinal lesions. The current study was conducted to investigate the value of endobronchial ultrasound-guided transbronchial needle aspiration in the diagnosis and differential diagnosis of isolated mediastinal lesions without lung abnormalities.We retrospectively analyzed the data of patients with isolated mediastinal lesions without lung abnormalities for whom endobronchial ultrasound-guided transbronchial needle aspiration examination was performed at the Department of Thoracic Surgery of Peking University People's Hospital, between September 2009 and December 2010. For patients who could not be diagnosed with endobronchial ultrasound-guided transbronchial needle aspiration, surgical biopsy or more than 6 months of clinical and imaging follow-up was carried out.Endobronchial ultrasound-guided transbronchial needle aspiration was performed for 60 patients with isolated mediastinal lesions. Correct diagnosis was made in 48 cases. Nineteen cases were malignant, and 29 were benign. The rate of correct diagnosis was 80%. The sensitivity, specificity, and accuracy of endobronchial ultrasound-guided transbronchial needle aspiration in distinguishing benign from malignant mediastinal lesions were 95%, 100%, and 98%, respectively. The examination was tolerable for all patients. No associated complications were observed.Endobronchial ultrasound-guided transbronchial needle aspiration is a safe and effective method of diagnosing mediastinal lesions.