Early initiation of chemoradiation following index craniotomy is associated with decreased survival in high-grade glioma

The Stupp protocol of post-resection external beam radiation therapy and concomitant temozolomide is the standard of care for patients with newly-diagnosed glioblastoma, with expanded use in anaplastic astrocytoma. However, the optimal interval between surgery and these adjuvant therapies, and its impact on survival, is unknown. To investigate this, de-identified claims from a large, private health insurance database were queried to identify adult patients who underwent index craniotomy for resection of a supratentorial neoplasm during the period 2005-2014 and began postoperative radiation and temozolomide within 13 weeks of surgery. A total of 2535 patients were assigned to groups based on interval from surgery to first radiation treatment of up to 4 weeks, 4-6 weeks, or 6-13 weeks. Of these, 1098 patients began radiation treatment within 4 weeks of craniotomy, 1019 between 4 and 6 weeks, and 418 between 6 and 13 weeks. There was significant regional variation in treatment schedule in the United States. Survival was calculated based on time from first craniotomy to death. Kaplan-Meier plot and multivariate Cox proportional hazard regression demonstrated a statistically significant association between earliest postoperative radiation and decreased survival (hazard ratio 1.31), along with older age and male sex. Earlier initiation of postoperative radiation for high-grade glioma is not associated with increased survival. Rather, beginning radiation treatment within 4 weeks of craniotomy was associated with significantly worse survival compared to initiation of treatment 4-13 weeks after craniotomy. This is the largest population-based study to date regarding timing of Stupp protocol initiation.