Study of the MIB-1 labeling index as a predictor of tumor progression in pilocytic astrocytomas in children and adolescents.
OBJECTIVE
The pilocytic astrocytoma (PA) is the most common childhood brain tumor. This report examines the MIB-1 labeling index (LI) as a predictor of progression-free survival (PFS) among childhood PAs.


METHODS
Consecutive PAs were examined to determine whether the MIB-1 LI was associated with tumor progression. Other variables evaluated included tumor location, use of adjuvant therapy, extent of resection, and age at diagnosis.


RESULTS
One hundred forty-one children were identified (mean +/- SD age, 7.6 +/- 4.7 years; range, 0.43 to 18.56 years); 118 children had adequate tissue for MIB-1 immunohistochemistry. The 5-year PFS was 61.25%. By log-rank analysis, an MIB-1 LI of more than 2.0 was associated with shortened PFS (P =.035). Patients with PAs who underwent complete surgical resection, had tumors located in the cerebellum, and were treated with surgery only also had more prolonged PFS (P =.001 for all). Tumors in the optic pathways were associated with a shorter PFS (P =.001). Restricting the evaluation of MIB-1 LI to only incompletely resected tumors revealed an insignificant trend of MIB-1 LI of more than 2.0 having a shortened PFS. Multivariate analysis demonstrated completely resected tumors and tumors located in the cerebellum as less likely to progress (P =.001 and.019, respectively).


CONCLUSIONS
Children with PAs with an MIB-1 LI of more than 2.0 have a shortened PFS. PAs that are completely resected and are located in the cerebellum have a prolonged PFS. This initial study suggests that the MIB-1 LI identifies a more aggressive subset of PAs. Further work should focus on elucidating features of pilocytic astocytomas that will identify prospectively children at risk for progression.
Bowers
Daniel C
DC
Department of Pediatrics, University of Texas Southwestern Medical School at Dallas, Dallas, TX 75390-9063, USA. daniel.bowers@ utsouthwestern.edu.
Gargan
Lynn
L
Kapur
Payal
P
Reisch
Joan S
JS
Mulne
Arlynn F
AF
Shapiro
Kenneth N
KN
Elterman
Roy D
RD
Winick
Naomi J
NJ
Margraf
Linda R
LR
D000293:Adolescent; D001254:Astrocytoma / Q000378:metabolism* / Q000473:pathology*; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology*; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D005260:Female; D006801:Humans; D007223:Infant; D019394:Ki-67 Antigen / Q000378:metabolism*; D008297:Male; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D016019:Survival Analysis
D019394:Ki-67 Antigen