Staging and Prognosis

Meeting Abstract

Prognostic significance of histologic subtyping in high grade astrocytoma: North Central Cancer Treatment Group (NCCTG) results

Ravi D Rao, Bernd W Scheithauer, Caterina Giannini, Nancy L Iturria, Judith R O'Fallon, Paul L Schaefer, Jan C Buckner

Mayo Clinic, Rochester, MN; Toledo Clinic, Toledo, OH

Goal. To evaluate the prognostic significance of histologic subtyping of high-grade astrocytomas (HGA), we analyzed outcomes in 3 prospective NCCTG clinical trials in newly diagnosed HGA (1980-1993).
All patients received radiation and nitrosourea-based chemotherapy.
Therapy did not influence outcome.
Pathology was centrally reviewed.

Materials. Of 900 patients, 833 had astrocytoma with no oligodendroglial/gliosarcomatous elements.
Of these, 130 (16%) were grade 3, 703 (84%) were grade 4.
Histological subtypes: 417 pure fibrillary [Fib] (grades 3/4: 75/342); 75 pure small cell [SC] (grades 3/ 4: 8 /67); 35 pure giant cell [GC] (grades 3/4: 2 /33); 32 pure gemistocytic [Gem] (grades 3/4: 14/18); 190 mixed (i.e. with a component of another subtype) Fib (grades 3/4: 14/176), and 84 mixed non-Fib subtypes (grades 3/4: 17/67).
ECOG-PS was £ 1 in 570 (68%), ³ 2 in 259 (32%), unrecorded in 4 (0.5%).
Surgery: biopsy: 213 (26%); gross total resection: 146 (18%); subtotal resection: 474 (57%).

Result. In grade 4 astrocytomas, pure Fib histology led to worse survival than pure GC (p=0.013), those without any Fib component (p=0.002), and those with non-Fib subtype histologies (p=0.025).
Among grade 3 astrocytomas, only those with pure-Gem histology had survival advantage over pure-Fib subtype that approached significance (p=0.0742). 
In all 833 astrocytomas, those with pure-Fib histology had a poorer survival than those with pure-Gem (p=0.006), and those that lacked any Fib component (p=0.005). 
Multivariate Classification and Regression Tree (CART) analysis identified age, grade and PS, but not histological subtype as significant covariates. 

Conclusions. Univariate analysis suggests that HGA containing Gem or GC elements have better outcomes when compared to pure Fib astrocytomas. 
CART analysis suggests that these differences are related to covariates of age, PS, and grade.

© Copyright 2002 American Society of Clinical Oncology