Intensity-modulated radiation therapy in newly diagnosed glioblastoma: A systematic review on clinical and technical issues

Background and purpose: Intensity-modulated radiation therapy (IMRT) could represent a new tool to improve the therapeutic ratio in the treatment of glioblastoma. This systematic review investigates the evidence behind the application of IMRT to glioblastoma, assessing the potential benefits from both the clinical and dosimetrical perspective. Materials and methods: Two independent researchers systematically identified all relevant articles available on PubMed and MEDLINE databases until December 2009. Results: Ultimately, seventeen studies were included in the analysis, for a total of 204 treated patients and 148 patient datasets used in planning studies. Most dosimetrical studies provided statistical analysis. Clinical series did not include any randomized controlled study, ultimately hindering a meta-analysis. From the dosimetrical point of view, conformal radiotherapy and IMRT provide similar results in terms of target coverage, while IMRT is better in terms of dose conformity, in reducing the maximum dose to the organs at risk and in healthy brain sparing. In clinical reports, a wide variability was recorded concerning dose per fraction, total dose, and chemotherapy administration. A comprehensive qualitative comparison with literature on similar non-IMRT clinical series showed that in most IMRT series excellent compliance and low rates of toxicity were recorded. Hypofractionated regimens in association with chemotherapy showed results that are even superior to the standard treatment. Conclusions: According to the available data, the dosimetrical advantages of IMRT translate into the clinical capability of delivering higher dose levels in a shorter time. This approach in glioblastoma patients with good prognosis suggests the possibility of improving outcomes without an increase in toxicity.