Others, however, have reported that the combination of CSF concentrations of CEA, neuron specific enolase (NSE) and cytokeratin 19 fragments (CYFRA21-1) using cut-off values without consideration of the respective serum levels appears to be useful for the detection of meningeal carcinomatosis of lung cancer [27]. This evidence concerns the gene CEACAM5 and leptomeningeal metastasis.