Radiation oncology in brain tumors: current approaches and clinical trials in progress

Radiation therapy remains a critical therapeutic modality in the treatment of adult brain tumors. However, its use continues to evolve depending on the histologic findings of the brain tumor. In high-grade gliomas, current trials focus on the addition of systemic agents and optimization of target delineation to improve the therapeutic ratio of radiotherapy. In low-grade gliomas, the life expectancy is much greater, and the possibility of late effects of radiotherapy have shaped contemporary trials to attempt to identify groups that benefit from radiotherapy versus the ones that may defer radiotherapy until tumor progression. With primary central nervous system lymphoma, the advent of high-dose methotrexate-based chemotherapy and the risk of severe early neurocognitive toxicity have brought the role of radiotherapy into question. With meningioma, the use of normal tissue-sparing techniques such as radiosurgery has allowed for the successful treatment of patients who are eminently curable and with a life expectancy that is generally no different than that of the general population. Particular attention in this review is paid to current approaches, contemporary trials, and modern therapeutic dilemmas.