Personalized radiation therapy for glioblastoma.

Glioblastoma is the most common primary brain tumor with an estimated 14,000 Americans diagnosed with this disease annually. This disease is treated with maximal surgical resection followed by adjuvant radiation therapy. Radiation therapy was initially delivered to the whole brain and with no concurrent or adjuvant systemic therapy. Advances in imaging and treatment delivery have allowed for partial brain irradiation to minimize radiation dose to normal structures, as well as sparing structures important for memory such as the hippocampus, decreasing morbidity and toxicity. While there is no consensus on the optimal radiation volume needed to successfully treat glioblastoma, there is consensus that the tumor bed with margin is preferable to treatment of the whole brain. Additionally, advances in knowledge regarding tumor biology have demonstrated the benefit of concurrent and adjuvant chemotherapy, as well as demonstrated that methylation of genes in the tumor can predispose greater responsiveness to chemotherapy. The following review describes the advancements in specific radiation techniques that have been used to improve the therapeutic ratio for management of glioblastoma and methods used to personalize radiation treatment for patients based on genomic markers as well as clinical factors. The review also describes future investigations that are currently taking place in order to enable a further improvement of clinical outcomes for patients with glioblastoma.