Can a higher radiation dose help older brain cancer patients live longer?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Histological confirmation of WHO grade 4 glioblastoma (IDH wild-type by immunohistochemistry or sequencing). Histopathology must be confirmed by central review. * Newly diagnosed disease, with time elapsed from diagnostic surgery/resection \<8 weeks. * Age ≥ 65 years old at time of glioblastoma diagnosis * Adequate functional status as measured by a ECOG Performance Status 0, 1 or 2, at time of enrollment. * Adequate hematological, renal and hepatic functions as defined by the following required laboratory values obtained within 45 days prior to randomization: Platelet count ≥ 100 x 10\^9/L (100,000 cells/mm\^3) Serum creatinine ≤ 1.5 times the upper limit of normal Total serum bilirubin ≤ 1.5 times the upper limit of normal ALT (SGPT) \< 2.5 times the upper limit of normal and/or AST (SGOT) \< 2.5 times the upper limit of normal -Patient may have received corticosteroids, but must be on a stable or decreasing dose for at least 14 days prior to randomization. Exclusion Criteria: * Participants with recurrent glioma. * Participants with evidence of spinal, leptomeningeal, or more distant disease. * Participants with another active central nervous system malignancies requiring treatment. * Participants with a second invasive malignancy that is A) incompletely treated or requiring ongoing treatment, or B) reasonably anticipated to be associated with a median overall survival of less than 1 year based on population-level data for the specified disease site and stage. * Participants with any other major medical illnesses or psychiatric treatments that in the treating physician's opinion will prevent administration or completion of protocol therapy. * Participants with inadequate mental capacity to provide informed consent * Participants who cannot receive gadolinium * Participants who have undergone prior head and neck or cranial radiation or radiation to any other site previously that would be reasonably anticipated to result in a significant overlap in radiation fields. * Participants who have received systemic or radiosensitizing therapy for a prior head and neck or central nervous system malignancy or any investigational cancer drug for glioblastoma prior to randomization. * Participants who have received or plan to receive any other form of non-surgical local or field treatment overlapping with the anticipated radiation field. * Patients with a serious active infection (such as a wound infection requiring parenteral antibiotics) or other acute medical conditions at the time of randomization that would impair the ability of the patient to receive protocol treatment.