PROLIFERATIVE ACTIVITY AND PROGNOSIS OF LOW-GRADE ASTROCYTOMAS

Well-differentiated astrocytomas may transform into malignant astrocyt omas in time. In surgical specimens, when the histological picture str ictly corresponds to that of grade II glioma, the transformation is un predictable. Clinically, the bad outcome of a quota of astrocytomas is a well known phenomenon. The use of proliferation markers, and recent ly of MIB-1 LI, for detecting the proliferation potential comes out to be a useful tool for prognosis. A survival analysis of fifty astrocyt omas grade II according to the WHO classification was performed with u nivariate and multivariate analysis of a series of clinical and histol ogical parameters. MIB-1 LI was calculated and compared with all the o ther parameters. A cut-off of 8% of MIB-1 LI divided the astrocytomas in two groups with significantly different survival (p = 0.0066): medi an survival time of 1062 versus 1686 days. According to multivariate a nalysis MIB-1 LI resulted to be an independent factor (p = 0.002) alon g with extension of surgical removal (partial versus total), postopera tive Karnofsky status (greater than or equal to 70 versus < 70) and ag e (less than or equal to 30 versus > 30). The interpretation of well-d ifferentiated astrocytomas with high MIB-1 LI is that the increasing n umber of cycling cells precedes phenotypic transformation. MIB-1 LI ca n be used as a prognostic factor.