Survival Outcomes of Elderly Patients With Glioblastoma Multiforme in Their 75th Year or Older Treated With Adjuvant Therapy.

Purpose: To assess the outcomes of the most elderly cohort of patients with a diagnosis of glioblastoma multiforme (GBM) after intensity modulated radiation therapy (IMRT).

Methods And Materials: The data of patients with GBM who had underwent IMRT from May 2007 to December 2015 were entered into a prospective database. Analysis was performed on the data from patients diagnosed during or after 75 years of age. The primary endpoint was the median survival. Univariate and multivariate analyses were performed with respect to survival for patients aged 74 to 80 versus >80 years, Eastern Cooperative Oncology Group performance status of 0 to 1 versus 2 to 3, extent of resection, a high radiation dose (60 Gy) versus any hypofractionated schedule, MGMT methylation status, planning target volume, and the use of temozolomide (TMZ) versus no TMZ.

Results: Of the 108 patients, 35 received best supportive care, 1 received TMZ alone, 40 received RT alone, and 32 received combined RT and TMZ. IMRT was delivered with a hypofractionated technique (40 Gy) in 58 patients or long-course RT (60 Gy) in 11 patients. The median age was 79 years, with 61.6% of patients aged 74 to 80 years and 38.4% aged >80 years. Of the 108 patients, 64 died during the follow-up period, with a median survival of 10 months (95% confidence interval 7.1-11.9), projected 12-month survival rate of 35.6%, and 24-month survival rate of 7.9%. On univariate analysis, the independent predictors of survival included younger age (P=.02), better performance status (P=.014), greater resection extent (P=.002), and TMZ use (P<.001). MGMT methylation status, RT dose, and planning target volume showed no significant differences between the groups. Only chemotherapy use remained statistically significant (P=.035) on multivariate analysis.

Conclusion: The current data underrepresent elderly patients aged >75 years with GBM. Despite elderly patients having a worse prognosis, the results of the present study suggest the presence of survival benefits with IMRT for selected patients that can be further extended with addition of TMZ. Further study of this cohort and an understanding of the appropriate selection criteria are warranted.