To identify the effect of delaying the initiation of chemoradiation therapy (CRT) with Temozolomide after first surgical intervention on overall survival (OS) and progression free survival (PFS) in patients with newly diagnosed glioblastoma (GBM).

Currently, there is no standard or recommended time interval for post-surgical CRT initiation. There is conflicting information on the impact of when to initiate CRT in patients with newly diagnosed GBM. We examined the relationship of delay (up to 6 week) of CRT initiation on outcomes in newly diagnosed GBM treated at our tertiary care center.

We reviewed 465 charts of GBM patients from July 2012 to September 2015. Patients underwent surgical resection or biopsy, and received CRT post-operatively as per Stupp protocol. A multivariate proportional hazard Cox model was used to assess an association between CRT delay at < 4 weeks (short delay) vs. ≥ 4 to 6 weeks (long delay) and OS.

Of the 227 patients included in the final analysis, 124 patients began their CRT within 4 weeks of surgery. 134 were male, 77&shy; (33.9%) had MGMT methylation, 164 (72.2%) were IDH-wild type, and 91 (40.1%) were EGFR not amplified. Median OS was 14.8 and 15.5 months (p-value = 0.49) for the CRT initiation within 4 weeks compared to 4 or greater, respectively.    

The adjusted hazard ratio in the Cox-model analysis of the long delay cohort to the short delay cohort revealed no significant difference in either OS (HR = 1.14 ¦ p-value = 0.38 ¦ CI (97.5%) = 0.85 – 1.55) or PFS (HR = 1.03 ¦ p-value = 0.82 ¦ CI (97.5%) = 0.76 – 1.40).

There was not a significant difference in OS and PFS between patients who received CRT within 4 weeks of surgery and those who received CRT between 4 and 6 weeks.