Radiotherapy

Chapter 4 - Treatment Strategies for Anaplastic Astrocytoma and Glioblastoma

Radiotherapy (RT) was shown to double median survival in adult malignant glioma patients several decades ago.

Radiotherapy Figure 1

Courtesy M. Guckenberger, Zurich

The introduction of involved-field RT as opposed to whole brain RT has not compromised overall survival.

The involved field, defined with a safety margin of 2–3 cm, is important to capture the infiltration zone around the primary radiologically defined lesion.

The optimal dose regarding tolerability, safety and efficacy has been identified as 30 × 2 Gy, or hypofractionated variations thereof at a biologically equivalent dose, e.g. 15 × 2.66 Gy.

Dose escalations beyond 30 × 2 Gy or radiosurgical boosts do not improve local control.

Radiotherapy Figure 2

Courtesy W. Küker, Tübingen

More than 90% of glioblastomas recur within the irradiated target volume.

Re-irradiation is feasible in patients with circumscribed lesions, but has not been shown to improve overall survival.

Radiotherapy Figure 3

Courtesy A. Valavanis, Zurich

Radiation necrosis is seen less frequently with modern RT fractionations and techniques.

Bevacizumab may be more active than corticosteroids in treating symptomatic radiation necrosis.

Revision Questions

  1. What is the typical target volume of RT for anaplastic astrocytoma and glioblastoma?
  2. Which patients should be considered candidates for re-irradiation?
  3. What is the most effective pharmacological treatment for radiation necrosis?

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Last update: 18 September 2017