Resection and survival in glioblastoma multiforme: An RTOG recursive partitioning analysis of ALA study patients

TLDR

The benefit of cytoreductive surgery for glioblastoma multiforme is unclear, with prior series showing selection bias. This study examined whether fluorescence‑guided resections using 5‑aminolevulinic acid improve outcomes and whether the Radiation Therapy Oncology Group recursive partitioning analysis predicts survival and benefits from extensive resections by RPA class. A cohort of 243 newly diagnosed GBM patients underwent surgery with or without ALA, received radiotherapy, had postoperative MRI, and were stratified into RTOG‑RPA classes III–V based on age, KPS, neurological status, and mental status. Survival declined with higher RPA class (median OS 17.8, 14.7, 10.7 months for classes III–V), complete resections significantly extended survival in classes IV and V but not III, and the RTOG‑RPA accurately predicted survival, supporting a causal benefit of resection.

Abstract

The benefit of cytoreductive surgery for glioblastoma multiforme (GBM) is unclear, and selection bias in past series has been observed. The 5-aminolevulinic acid (ALA) study investigated the influence of fluorescence-guided resections on outcome and generated an extensive database of GBM patients with optimized resections. We evaluated whether the Radiation Therapy Oncology Group recursive partitioning analysis (RTOG-RPA) would predict survival of these patients and whether there was any benefit from extensive resections depending on RPA class. A total of 243 per-protocol patients with newly diagnosed GBM were operated on with or without ALA and treated by radiotherapy. Postoperative MRI was obtained in all patients. Patients were allocated into RTOG-RPA classes III–V based on age, KPS, neurological condition, and mental status (as derived from the NIH Stroke Scale). Median overall survival among RPA classes III, IV, and V was 17.8, 14.7, and 10.7 months, respectively, with 2-year survival rates of 26%, 12%, and 7% (p = 0.0007). Stratified for degree of resection, survival of patients with complete resections was clearly longer in RPA classes IV and V (17.7 months vs. 12.9 months, p = 0.0015, and 13.7 months vs. 10.4 months, p = 0.0398; 2-year rates: 21.0% vs. 4.4% and 11.1% vs. 2.6%, respectively), but was not in the small subgroup of RPA class III patients (19.3 vs. 16.3 months, p = 0.14). Survival of patients from the ALA study is correctly predicted by the RTOG-RPA classes. Differences in survival depending on resection status, especially in RPA classes IV and V, support a causal influence of resection on survival.