Impact of timing of radiotherapy in patients with newly diagnosed glioblastoma

- In patients with a GBM, delay in RT >28 days after surgery does not worsen PFS or OS.
- In patients with STR or biopsy, a delay in RT >28 days improves PFS.
- In patients with STR or biopsy, a delay in RT >28 days improves OS.

ObjectiveTo further evaluate if a delay in the start of radiation therapy (RT) affects patient outcomes for glioblastoma (GBM).Patients and methodsFrom May 1999 to May 2010, a total of 161 patients underwent surgery followed by RT for GBM. We assessed overall survival (OS) and progression free survival (PFS), stratified by extent of surgical resection. Included in the analysis were genomic predictors of progression.ResultsMedian time from surgery to start of RT was 20 days for biopsy alone, 28 days for subtotal resection (STR) and 28 days for gross total resection (GTR). For all patients, a delay >28 days did not result in a difference in PFS when compared to no delay (6.7 vs. 6.9 months, p = 0.07). PFS was improved in biopsy or STR patients with a >28 day delay to start of RT (4.2 vs. 6.7 months, p = 0.006). OS was also improved in patients receiving biopsy or STR with a >28 day delay to start of RT (12.3 vs. 7.8 months, p = 0.005). Multivariable analysis (MVA) demonstrated an improvement in OS and PFS with time to RT >28 days for biopsy or STR patients (HR 0.52 p = 0.008 and HR 0.48 p = 0.02, respectively).ConclusionIn this retrospective review of GBM patients treated at a single institution, OS and PFS were not different between time to RT >28 days compared to <28 days. There was a modest improvement in both PFS and OS in patients who received biopsy or STR with time to RT >28 days.