Recurrence following neurosurgeon-determined gross-total resection of adult supratentorial low-grade glioma: results of a prospective clinical trial

Abstract

Object: In 1998, the Radiation Therapy Oncology Group initiated a Phase II study of observation for adults < 40 years old with cerebral low-grade glioma who underwent a neurosurgeon-determined gross-total resection (GTR).

Methods: Patient eligibility criteria included the presence of a World Health Organization Grade II astrocytoma, oligodendroglioma, or mixed oligoastrocytoma confirmed histologically; age 18-39 years; Karnofsky Performance Scale score > or = 60; Neurologic Function Scale score < or = 3; supratentorial tumor location; neurosurgeon-determined GTR; and pre- and postoperative MR imaging with contrast enhancement available for central review by the principal investigator. Patients were observed following GTR and underwent MR imaging every 6 months. Prognostic factors analyzed for their contribution to patient overall survival, progression-free survival (PFS), and tumor recurrence included age, sex, Karnofsky Performance Scale score, Neurologic Function Scale score, histological type, contrast enhancement on preoperative MR imaging, preoperative tumor diameter, residual disease based on postoperative MR imaging, and baseline Mini-Mental State Examination score.

Results: Between 1998 and 2002, 111 eligible patients were entered into the study. In these 111 patients, the overall survival rates at 2 and 5 years were 99 and 93%, respectively. The PFS rates in these 111 patients at 2 and 5 years were 82 and 48%, respectively. Three prognostic factors predicted significantly poorer PFS in univariate and multivariate analyses: 1) preoperative tumor diameter > or = 4 cm; 2) astrocytoma/oligoastrocytoma histological type; and 3) residual tumor > or = 1 cm according to MR imaging. Review of the postoperative MR imaging results revealed that 59% of patients had < 1 cm residual disease (with a subsequent 26% recurrence rate), 32% had 1-2 cm residual disease (with a subsequent 68% recurrence rate), and 9% had > 2 cm residual disease (with a subsequent 89% recurrence rate).

Conclusions: These data suggest that young adult patients with low-grade glioma who undergo a neurosurgeon-determined GTR have a > 50% risk of tumor progression 5-years postoperatively, warranting close follow-up and consideration for adjuvant treatment.

Fig. 1

Preoperative (A and C) and postoperative (B and D) MR images of patients who underwent a neurosurgeon-determined GTR and were found to have < 1 cm of imaging-based residual disease (A and B) or 1–2 cm residual disease (C and D).

Fig. 2

Line graph showing the overall survival and PFS curves for the 111 patients with favorable (low risk) LGG and the 251 patients with unfavorable (high risk) LGG.

Fig. 3

Line graph showing patient PFS according to 2 different tumor diameters (< 4 cm vs ≥ 4 cm).

Fig. 4

Line graph showing patient PFS according to histological type (pure oligodendroglioma vs astrocytoma and mixed oligoastrocytoma).

Fig. 5

Line graph of patient PFS according to surgical residual tumor (< 1 cm vs ≥ 1 cm).

Fig. 6

Line graph showing patient PFS according to 3 different prognostic factor groups: the favorable group (< 1 cm residual tumor, tumor diameter < 4 cm, and oligodendroglioma histological type); the unfavorable group (≥ 1 cm residual tumor according to imaging, preoperative tumor diameter ≥ 4 cm, and astrocytoma histological type); and the group of patients with tumors with a mix of favorable and unfavorable characteristics.