ASCO has published a clinical practice guideline covering radiation therapy for glioblastoma. The guideline—which endorses recommendations released previously by ASTRO—addresses 4 overarching questions:

• When is radiation therapy indicated after biopsy/resection of glioblastoma (GBM) and how does systemic therapy modify its effects?
• What is the optimal dose-fractionation schedule for external beam radiation therapy after biopsy/resection of GBM and how might treatment vary based on pretreatment characteristics such as age or performance status?
• What are the ideal target volumes for curative-intent external beam radiotherapy of GBM?
• What is the role of reirradiation among patients with GBM whose disease recurs following completion of standard first-line therapy?

These ASCO recommendations are in addition to ASTRO suggestions:

• Radiation should be initiated as soon as it is safely permissible.
• The impact of bevacizumab to standard therapy on health-related quality of life requires further validation.
• The optimal dose-fractionation schedule has not yet been determined for elderly patients.
• There is no prospective evidence supporting reirradiation in any patient subgroup.