Baseline serum/cerebrospinal fluid ratio of carcinoembryonic antigen and carbohydrate antigen series biomarkers in non-neoplastic diseases: a cross-sectional study on 224 patients.

BACKGROUND: The measurement of carcinoembryonic antigen, carbohydrate antigen series biomarkers in cerebrospinal fluid (CSF), is useful for the diagnosis of brain metastasis and leptomeningeal metastases to a certain extent. Their serum/CSF ratios may be of benefit to earlier diagnosis and treatment. However, the normal reference values of the ratios were not available. Accordingly, in this study we analyzed the serum/CSF ratios of tumor markers levels in non-neoplastic diseases patients for possible normal values.

MATERIAL AND METHODS: We screened our database for paired CSF and serum samples which have been collected by lumbar puncture. 224 pairs of CSF and serum samples were obtained and compared. The 97.5th percentile, maximum value, and their serum/CSF ratios were obtained.

RESULTS: The 97.5th percentile and maximum value of CSF CEA, CA125, CA19-9, CA15-3, CA724, and CYFRA21-1 concentration for overall participants were 0.572 μ/mL, 4.343 μ/mL, 2.872 μ/mL, 2.108 μ/mL, 1.62 μ/mL, and 1.997 μ/mL, respectively. Gender had no significant difference in these CSF biomarkers except CA15-3. The 97.5th percentile serum/CSF ratio of CEA, CA125, CA19-9, CA15-3, CA724, and CYFRA21-1 level were 34.554, 44.772, 51.232, 20.941, 20.737, and 5.389 respectively. The serum/CSF ratios in different age groups were also described.

CONCLUSIONS: Here, serum/CSF ratios of six tumor markers were determined in non-neoplastic diseases. The usefulness of this index for diagnosis, management, and prognostic utility of leptomeningeal metastases must be validated in larger cohort studies over the long term.