Treatment Protocols and Outcomes of Intraoperative Radiotherapy for Brain Metastases: A Systematic Review

Intraoperative radiotherapy (IORT) is the delivery of ionizing radiation to the tumor or tumor bed during surgery while the targeted tissue is exposed.[1] In contrast to other radiation modalities such as whole brain radiotherapy (WBRT), external beam radiotherapy (EBRT), and stereotactic radiosurgery (SRS), IORT has the advantages of increased precision and minimal radiation exposure to adjacent normal tissues,[2] thereby minimizing side effects. Because IORT is administered at the time of surgery, there is also the theoretical advantage of preventing tumor cell repopulation by not giving them time to proliferate, as may be the case in post-operative radiotherapy (RT).[3,4] Patient satisfaction and convenience are also improved since the surgery and radiation are performed in the same sitting,[5] potentially decreasing the duration of treatment. Given these advantages, IORT has been used in a wide range of Juan Silvestre G. Pascual,1 Ella Mae D. Cruz-Lim,2 Aveline Marie D. Ylanan,2 Katrina Hannah D. Ignacio,3 Johanna Patricia A. Cañal,2 Kathleen Joy O. Khu1