Comparison of Cyclin A and MIB-1 expression in astrocytic tumors using image-based cell analysis system

Traditional prognostic indicators for astrocytic tumors include tumor size, type, and histologic grade. Data suggest that tumor growth fraction assess ed by MIB-1 is an important predicator of survival. Cyclin A, like MIB-1, i s a recently described specific marker of proliferation, detectable primari ly in S phase of the cell cycle as it undergoes progression to G2 phase. Th irty-seven cases of astrocytic tumors-14 cases of World Health Organization grade 1 and 2 (low grade tumors), 8 cases of grade 3 (anaplastic astrocyto ma), and 15 cases of grade 4 (glio-blastoma multiforme)-were simultaneously evaluated using routine paraffin immunohistochemical methods with commerci al antibodies against MIB-1 and cyclin A. The results were quantitated usin g a Cell Analysis System (CAS) 200 image analyzer. The mean percentage posi tive nuclear area for MLB-I was 3.32% in grade 1 and 2, 19.27% in grade 3, and 24.00% in grade 4 astrocytic tumors. Cyclin A showed a similar pattern of positivity in the same cases: 2.84% in grade 1 and 2, 16.27% in grade 3, and 24.88% in grade 4 astrocytic tumors. The data suggest that both prolif eration markers correlated significantly with histologic grade. Cyclin A ap pears to be as good an indicator of brain tumor proliferation as MIB-1. Bec ause cyclin A is detectable primarily in the S phase of the cell cycle, the fraction of cells positive for cyclin A should allow for a more accurate i ndicator of tumor progression.