Age-dependent rate of anaplastic transformation in low-grade astrocytoma

Age and histologic grade are interrelated characteristics of diffuse fibril lary astrocytomas, because the peak age incidence rises with increasing gra de. The relationship between age and grade may be explained if age determin es the rate of anaplastic progression in astrocytomas. The authors tested t his hypothesis by determining the interval between diagnosis of low-grade a strocytoma and progression to high-grade astrocytoma in patients of various ages. A two-way scatterplot of age at initial diagnosis versus interval to anaplastic progression demonstrated a strong negative correlation (n = 24; Pearson correlation coefficient = -0.83; Spearman correlation coefficient = -0.79; p < 0.001 for both values). It was concluded that the rate of anap lastic progression in low-grade astrocytoma is directly correlated with pat ient age.