MIB-1 labeling index in nonpilocytic astrocytoma of childhood: A study of 101 cases

BACKGROUND. The prognosis of pediatric patients with nonpilocytic astrocytoma, and in particular those with anaplastic astrocytoma, is somewhat unpredictable. This study used MIB-1 monoclonal antibody, a proliferative marker that can be used in formalin fixed paraffin embedded tissues, to study nonpilocytic pediatric astrocytoma. METHODS. Astrocytoma, anaplastic astrocytoma, and glioblastoma specimens excised from a total of 101 pediatric patients during the period from January 1975 to September 1996 were retrieved from the authors' surgical pathology file. Histologic grading of the specimens was performed based on a modified Ringertz system. The proliferative potential of the tumors was estimated by using the MIB-1 labeling index (LI), which was evaluated with morphologic grades of tumors and survival of the patients. RESULTS. Of the 101 patients, 34 had astrocytoma, 33 had anaplastic astrocytoma, and 34 had glioblastoma. Their mean survival times were 165.2 ± 14.9 months (mean ± standard error; SE), 46.1 ± 9.9 months, and 21.8 ± 5.6 months, respectively. The mean MIB-1 LI of different tumor grades were as follows: astrocytoma, 3.9 ± 4.3 (mean ± standard deviation; range, 0.0-21.6); anaplastic astrocytoma, 24.3 ± 15.6 (range, 1.7-62.8); and glioblastoma, 35.9 ± 16.4 (range, 7.36-63.3). The mean survival of the entire group of patients with LIs ≤ 11 was 173.2 ± 12.2 months (mean ± SE), and the mean survival of those with LIs > 11 was 20.3 ± 4.1 months. The survival of anaplastic astrocytoma patients with LIs ≤ 11 was similar to that of astrocytoma patients, whereas the survival of anaplastic astrocytoma patients with LI > 11 was similar to that of patients with glioblastoma. CONCLUSIONS. The results of the current study show that histopathologic grading can predict the outcome for patients with astrocytomas and glioblastomas, whereas MIB-1 LI can separate better and worse prognostic groups in patients with anaplastic astrocytoma.