Diagnostic sensitivity of serum and lumbar CSF bHCG in newly diagnosed CNS germinoma

Abstract

Marked elevations of AFP and bHCG in serum or CSF may serve as surrogate diagnostic markers in lieu of histology for primary CNS mixed, malignant germ cell tumors. There is less information on the diagnostic sensitivity of bHCG assays in germinoma. We report baseline serum and lumbar CSF bHCG values in 58 newly diagnosed, histologically confirmed germinoma patients gathered from two prospective clinical trials which required that patients have a normal AFP and bHCG ≤50 mIU/ml in serum and lumbar CSF. The location of the primary tumors was: suprasellar(23); pineal(20); suprasellar/pineal(9); and other sites(6). The mean age of the study population was 13.5 (4.3-25.9) years. A total of 23(40%) patients had elevations of bHCG in either serum or CSF, 20(34.5%) of whom had only bHCG elevations in CSF. The patients' bHCG profiles were divided into four categories: I (normal serum and lumbar CSF bHCG), 35(60%); II (normal serum and elevated CSF bHCG), 20(34.5%); III (elevated serum and CSF bHCG), 2(3.5%); and IV (elevated serum and normal CSF bHCG), 1(2%). The median CSF bHCG level was 7.7(2.5-16) in the 22 patients with abnormal CSF values and the lumbar value was higher than the serum value in 20 of 23(87%) patients with bHCG elevations. Lumbar CSF was a more informative screen for bHCG than serum but the majority of patients (60%) had normal bHCG values at diagnosis. Until a more sensitive tumor marker for germinoma is devised, histologic confirmation remains the standard of care. Pediatr Blood Cancer 2012; 59: 1180-1182. © 2012 Wiley Periodicals, Inc.