The potential impact of delayed radiation therapy on patients with glioblastoma

Abstract

Background: Radiation therapy (RT) is the major component of glioblastoma treatment; however, the time to initiate RT after surgical intervention varies between institutions. Our study examined the time from diagnosis to the initiation of RT and its effects on overall patient survival. Methods: We retrospectively examined 267 patients with glioblastoma who received RT as part of their therapy in two Canadian tertiary care centers. The primary goal of the study is to assess if time to RT can predict/impact survival in glioblastoma patients. Results: The following variables were associated with an increased risk of death: hazard ratio (HR) of time to RT was 0.95 [95% confidence interval (CI), 0.91-0.99] for every extra week. HRs for the type of surgery (resection or biopsy) and type of management received (standard of care in comparison with RT regardless of chemotherapeutic agents other than concomitant and adjuvant temozolomide) were 0.50 (95% CI, 0.37-0.66) and 0.53 (95% CI, 0.38-0.75), respectively. HR for age was 1.02 (95% CI, 1.01-1.03) for every extra year. Standard 60 Gy RT HR was 0.70 [95% confidence interval (CI), 0.51-0.97] in younger patients. Conclusions: The time from diagnosis to the initiation of RT was found to be a significant prognostic factor for overall patient survival. The addition of temozolomide to the treatment protocol, age, standard RT dose in younger patients and extent of surgery are others factors associated with longer survival periods.