Diagnostic utility and correlation of tumor markers in the serum and cerebrospinal fluid of children with intracranial germ cell tumors

Abstract

In order to predict whether tumor markers assist in the histopathologic diagnosis of germ cell tumors (GCTs), we analyzed the correlation of beta human chorionic gonadotropin (βhCG) and alpha-fetoprotein (AFP) in serum and cerebrospinal fluid (CSF) samples at baseline and subsequent follow-up examinations. A retrospective study of patients diagnosed with intracranial GCTs between July 1985 and February 2011 at our institution was conducted to review clinical, surgical, radiological, laboratory, and histopathologic data. Of the 67 patients eligible for the study, 42 had germinomas and 25 non-germinomatous GCTs. At baseline, serum and CSF AFP agreed in 97.9 % of patients (Cohen's Kappa 0.93). Baseline βhCG samples agreed in only 72.5 % of patients (Cohen's Kappa 0.46). In most cases, values were higher in serum for AFP and in CSF for βhCG. ROC curves estimated from logistic regression model indicated that CSF and serum samples had almost equal diagnostic utility, and the DeLong test showed that the difference in area under curves was not statistically significant. During follow-up (185 paired CSF and serum values from 43 patients), 90.3 % of AFP values correlated between CSF and serum (Cohen's Kappa 0.22, showing fair agreement). For βhCG, 96.2 % of values agreed in serum and CSF (Cohen's Kappa 0.61). In some patients, intracranial GCTs can be diagnosed based solely upon positive serum AFP values. In addition, marker values from serum only may be sufficient to predict tumor relapse at interval follow-up examinations.