Glial fibrillary acidic protein and neurofilament protein in medulloblastoma

Medulloblastoma is the most common primitive neuroectodermal tumor (PNET) with the potential to differentiate along glial or neuronal lines. Thirty cases of medulloblastoma were tested by the peroxidase-antiperoxidase (PAP) method with anti-GFAP serum (DAKO) and by the avidin-biotin peroxidase complex (ABC) method with 68kd subunit of anti-NF antibody. All the cases were classified into three subtypes based on these immunohistochemical findings and were analyzed in relation to clinico-pathological features. Fifteen of thirty medulloblastomas contained GFAP positive cells, seventeen showed cells reacting to NF. The reactions for both proteins were present in eight medulloblastomas (PNET-BD, bipotential differentiation). Seventeen medulloblastomas reacted to only one protein (PNET-MD, monopotential differentiation). No reaction for either was found in five cases (PNET-NOS, not otherwise specified). The two year survival rate was 12.5% for PNET-BD compared to 49.2% for PNET-MD and 53.3% for PNET-NOS. Nine variables, i.e. age, tumor stage, metastatic stage, operation, radiotherapy, chemotherapy, histology, GFAP and NF, were analyzed using Cox's proportional hazard model. This revealed that the significant factors were tumor stage (p = 0.0002), GFAP (p = 0.0008) and operation (p less than 0.05). In conclusion, GFAP is the most important histological factor for prognosis and medulloblastoma without glial differentiation has a much better prognosis than one with glial differentiation.