Sensitive Detection of EGFR Mutations in Cerebrospinal Fluid from Lung Adenocarcinoma Patients with Brain Metastases

Epidermal growth factor receptor (EGFR) mutations in cerebrospinal fluid (CSF) might be useful predictive markers for EGFR tyrosine kinase inhibitor treatment of intracranial metastatic tumors. In this retrospective study, amplification refractory mutation system (ARMS)-PCR assays were used to investigate the EGFR gene status in 30 lung adenocarcinoma patients with brain metastases. A total of 16 patients tested positive for EGFR-activating mutations in CSF or tumor tissues. These included L858R mutation in exon 21 in six CSF samples and exon 19 deletions in seven CSF samples. EGFR mutations were detected between CSF and primary tumor samples with a 75% positive predictive value (95% CI, 0.45-1.00), 75% negative predictive value (95% CI, 0.51-0.99), 67% sensitivity (95% CI, 0.36-0.97), and 82% specificity (95% CI, 0.59-1.00). Most of the patients who had EGFR mutations in CSF achieved good responses with EGFR-tyrosine kinase inhibitor treatment. In conclusion, ARMS-PCR could be a sensitive method of detecting EGFR mutations. in the CSF of patients with lung adenocarcinoma with brain metastases. As such, ARMS-PCR could play an important role in guiding EGFR-tyrosine kinase inhibitor treatments of intracranial tumors and for diagnosing brain metastases in patients with lung adenocarcinoma.