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Comparison of mixed anaplastic oligoastrocytoma and high-grade astrocytoma in North Central Cancer Treatment Group (NCCTG) clinical trials of high-grade glioma
Jan C Buckner, Bernd W Scheithauer, Robert P Dinapoli, Henry J Votava, Caterina Giannini, Nancy Iturria, Judith O´Fallon, Mayo Clinic, Rochester, MN; Fargo Clinic, Fargo, ND.
Mixed oligoastrocytomas>/b> (OA) are relatively uncommon high-grade gliomas. While oligodendroglial elements are thought to be associated with better outcomes, the magnitude of the difference is not clear.
Methods: Between 1980 and 1999, Mayo Clinic and the NCCTG conducted 10 trials of radiation therapy and chemotherapy in adult patients with newly-diagnosed high-grade gliomas. All pathology slides were reviewed by one of the authors (BWS or CG) and classified by histologic cell type and grade without knowledge of outcomes. We grouped patients by grade and cell type, generated Kaplan-Meier survival distributions, compared distributions by the log-rank statistic, and performed multivariate Classification and Regression Tree (CART) analysis.
Results: Of 1368 patients, 69 (5%) had OA (22 Grade 3 (OA3); 47 grade 4(OA4)}, 152 (11%) had anaplastic astrocytoma (AA), and 1147 (84%) had glioblastoma multiforme (GBM). Median age and survival are summarized in the table below. Patients with OA3 survived significantly longer than those with OA4 (p=0.0003) or AA (p=0.0064). Patients with OA4 lived significantly longer than those with GBM (p=0.0004) but died faster than those with AA (p=0.198). Prognostic factors identified by CART analysis were histology, age, ECOG performance score, and extent of surgical resection, but not treatment administered.
Conclusions: Patients with anaplastic mixed oligoastrocytoma have distinct outcomes based upon grade (OA3 vs OA4) and in comparison with pure astrocytoma (AA or GBM). Future trials which include more than one histologic entity need to report results by cell type and grade and account for the varying prognoses in interpreting treatment outcomes.
N Median Age Median Survival (months) 2-Year Survival
OA3 22 39.5 52.3 81.8%
OA4 47 56 15.6 32.4%
AA 152 44 18.8 44.7%
GBM 1147 58 10.9 12.5%
Source: ASCO