Fig. 4

Both CDKN2A homozygous loss and histologic grade are independent predictors of survival in primary and first recurrence IDHm astrocytomas. K–M survival curves (colored lines) and Weibull AFT models (gray lines) for primary tumors (a) and first recurrences (b), stratified by percent homozygous CDKN2A deletion (left) and WHO histologic grade (right). For primary tumors, ≥ 30% CDKN2A homozygous deletion is associated with significantly shorter survivals than < 30% loss. While there was no separation between histologic grades 2 and 3, histologic grade 4 tumors showed significantly shorter survival than grades 2 and 3 combined. For first recurrence tumors, ≥ 30% CDKN2A deletion is similarly associated with shorter overall survival. By morphologic grading, survival of recurrent grade 3 tumors tracked closely with recurrent grade 4 tumors, both of which were significantly shorter than grade 2 tumors. The observed survival functions (K-M curves) closely track the parametric Weibull AFT model which separates the effects of CDKN2A deletion and histologic grade