Ependymomas: MIB-1 proliferation index and survival

The biologic behavior of ependymomas is highly variable, and its correlatio n with histologic features is at best imprecise. This retrospective study a ttempted to correlate the malignant histologic characteristics of ependymom as with MIB-1 proliferation index and survival. Biopsy and resection specim ens taken from 34 patients who received treatment 1972 to 1996 were histolo gically examined. The patients' ages range was 1 to 59 years. The histologi c specimens were assessed for anaplastic features (necrosis, mitosis, vascu lar proliferation, cellular pleomorphism, and overlapping of nuclei) and an MIB-1. (Ki-67 antigen) proliferation index was also determined. The overal l median MIB-1 proliferation index was 7.8% (range 0.1 - 62.5 %). An MIB-1 of 20% was significant for a decrease in survival (RR = 5.7) (p = 0.0013). The median MIB-1 for patients < 20 years old was 20.6 % with range (0.1, 43 %), while that for patients > 20 years was 5.1% (range 0.2, 9.4%) (KW p = 0.055). Three of 5 histological features evaluated were significantly assoc iated with outcome: > 5 mitotic figures per high-power field, necrosis, and vascular proliferation, but not nuclear overlap or pleomorphism. All patho logic factors except pleomorphism were significantly related to the MIB-1 p roliferation index. In brief, our data support the association of poor prog noses in ependymomas with young age, the presence of three to four anaplast ic histologic features, and an MIB-1 proliferation index > 20 %.