THE INFLUENCE OF VOLUMETRIC TUMOR DOUBLING TIME, DNA-PLOIDY, AND HISTOLOGIC GRADE ON THE SURVIVAL OF PATIENTS WITH INTRACRANIAL ASTROCYTOMAS

PURPOSE: To improve the prediction of individual survival in patients with intracranial astrocytomas through the analysis of volumetric tumo r doubling time (VDt) and DNA ploidy. METHODS: A pilot study was retro spectively conducted on a group of 25 patients with intracranial astro cytomas in whom recurrent and/or progressive disease was observed on s erial contrast-enhanced CT or MR examinations. VDt was computed using two or more data points from a semilogarithmic plot of tumor volume ve rsus time. Size-adjusted survival was calculated using a method based on VDt and initial tumor volume to decrease the lead time bias attribu table to differing tumor sizes at presentation. RESULTS: Slower VDt wa s associated with significantly longer survival and size-adjusted surv ival as determined by a univariate Cox proportional hazard analysis. A neuploidy was a significant indicator of poor survival. Aneuploid and multiclonal astrocytomas had poor size-adjusted survivals compared wit h diploid astrocytomas. Grade IV astrocytomas had significantly poorer survival and size-adjusted survival compared with lower grades (I to III), which individually were not significantly correlated. However, g rade IV histology was not a significant independent predictor of size- adjusted survival in a multivariate Cox model, whereas VDt and DNA plo idy remained significant. VDt also had a significant direct linear cor relation to survival and size-adjusted survival. CONCLUSIONS: VDt and DNA ploidy were more sensitive than histologic grading as indicators o f individual survival. Initial tumor size needs to be considered when staging and assessing survival in patients with intracranial astrocyto mas.