Background: Liquid biopsy allows the identification of targetable cancer mutations in a minimally invasive manner. In patients with advanced non-small cell lung cancer (NSCLC), droplet digital PCR (ddPCR) is increasingly used to genotype the epidermal growth factor receptor (EGFR) gene in circulating cell-free DNA (cfDNA). However, the sensitivity of this method is still under debate. The aim of this study was to implement and assess the performance of a ddPCR assay for detecting the EGFR T790M mutation in liquid biopsies.Methods: A ddPCR assay was optimized to detect the EGFR T790M mutation in plasma samples from 77 patients with NSCLC in progression.Results: Our ddPCR assay enabled the detection and quantification of the EGFR T790M mutation at cfDNA allele frequency as low as 0.5%. The mutation was detected in 40 plasma samples, corresponding to a positivity rate of 52%. The number of mutant molecules per mL of plasma ranged from 1 to 6,000. A rebiopsy was analyzed for 12 patients that had a negative plasma test and the mutation was detected in 2 cases.A second liquid biopsy was performed for 6 patients and the mutation was detected in 3 cases.Conclusions: This study highlights the value of ddPCR to detect and quantify the EGFR T790M mutation in liquid biopsies in a real-world clinical setting. Our results suggest that repeated ddPCR tests in cfDNA may obviate tissue re-biopsy in patients unable to provide a tumor tissue sample suitable for molecular analysis.
Paradoxical embolism is an uncommon phenomenon, accounting for only 2% of all cases of systemic arterial embolism. This condition suggests the presence of a patent foramen ovale, present in 20% - 25% of the adult population. The authors report the case of a 63-year-old male patient with a history of lung adenocarcinoma and hereditary thrombophilia admitted to hospital with acute onset of dyspnea, diplopia, confusion and decreased motor strength of the right limbs. Cranial computed tomography scan showed acute ischemic injury in the left posterior cerebral artery and computed tomography pulmonary angiography revealed bilateral pulmonary thromboembolism. A transesophageal echocardiogram confirmed the presence of patent foramen ovale. The patient was treated with anticoagulant therapy with progressive clinical improvement. Due to a high risk of recurrent thromboembolic episodes, the percutaneous closure of patent foramen ovale was performed and anticoagulant therapy was maintained indefinitely.
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