Objective: To analyze the correlation between the concentration of plasma cell free DNA (cfDNA) of patients with lung cancer or esophageal cancer and clinical features, and to assess the coincidence rate of the EGFR/KRAS mutations between the cfDNA and tumor tissue DNA.
Methods: A total of 30 cases lung cancer and esophageal cancer (including 15 lung cancer, 15 esophageal cancer) were enrolled in this study. The tumor tissue and plasma sample of patients were collected. The tumor tissue DNA and plasma cfDNA were extracted. The EGFR/KRAS mutations of the tumor tissue DNA and plasma cfDNA were detected by fluorescence PCR.
Results: The concentration of cfDNA of patients with lung cancer (5.0 ± 1.4) μg/L and esophageal cancer (7.0 ± 0.8) μg/L were positively correlated with tumor size (r = 0.574, P = 0.01). There was no significant correlation between the concentration of cfDNA and TNM stage of tumor, gender, and age of patients. There was no EGFR/KRAS gene mutations in tumor tissue DNA and plasma cfDNA of esophageal cancer. A total of 6 tumor tissue samples of lung cancer patients were detected EGFR mutation, and 1 tumor tissue sample was detected KRAS mutation. Meanwhile, 4 plasma cfDNA samples of lung cancer patients were detected EGFR mutation, and 1 plasma cfDNA sample was detected KRAS mutation.
Conclusion: The concentration of cfDNA of patients with lung cancer and esophageal cancer was positively correlated with tumor burden. There was high coincidence rate of the EGFR/KRAS mutations between the cfDNA and tumor tissue DNA.