Image: A histopathology of a brain showing metastatic lesions from a patient with non-small cell lung cancer (Photo courtesy of Peter Anderson).
The analysis of mutations in cerebrospinal fluid of lung cancer patients with brain metastases has been explored. Tumor tissue from brain metastasis is difficult to obtain and therefore less invasive methods are needed to identify and monitor the presence of known actionable mutations.
Brain metastases are a frequent complication of non-small cell lung cancer (NSCLC), especially in patients with lung adenocarcinoma. Patients with epidermal growth factor receptor (EGFR) mutations benefit from EGFR tyrosine kinase inhibitors (TKIs), but most relapse within one or two years, many with brain metastases.
A team of scientists working with those at Zhengzhou University (Zhengzhou City, China) compared EGFR mutation status in blood and cerebrospinal fluid and their relationship to neurological symptoms and leptomeningeal metastases. The study included 41 lung adenocarcinoma patients with EGFR mutations and brain metastases. EGFR mutation status was analyzed in the blood of 37 patients and cerebrospinal fluid of all patients. The presence of leptomeningeal metastases was assessed with magnetic resonance imaging (MRI).
The investigators found that in the entire study population, the rate of EGFR mutations in blood (65%) was significantly higher than in cerebrospinal fluid (37%). Eleven patients had leptomeningeal metastases detected by MRI. The rate of EGFR mutations in cerebrospinal fluid was significantly higher in patients with leptomeningeal metastases (73%) than in those without leptomeningeal metastases (23%). Neurological symptoms were present in 27 patients and the rate of EGFR mutations in cerebrospinal fluid was significantly higher in patients with neurological symptoms (48%) than in those without symptoms (14%).
Stefan Zimmermann, MD, a Medical Oncologist at Lausanne University Hospital (Lausanne, Switzerland) said, “Genotyping of cell-free DNA using droplet digital polymerase chain reaction (PCR) in cerebrospinal fluid as a less invasive modality to identify and monitor the presence of known actionable mutations is certainly interesting, as tumor tissue from brain metastasis is difficult to obtain.” There is now a consensus among global experts that liquid biopsy using blood samples should be used to test for T790M and EGFR mutations in patients with NSCLC when tumor tissue is not available. The study was presented at the European Society for Medical Oncology Asia 2017 Congress held November 17-19, 2017, in Singapore.
Lausanne University Hospital