Surgical treatment of metastatic brain tumors combined with intraoperative radiation therapy (IORT)

Intraoperative radiation therapy (IORT) was performed at the time of operation in 9 of 22 patients with brain metastases. The tumor bed was irradiated with the dose of 25 Gy (8 MeV, 400 cGy/min) following gross total removal of the tumor. The electron beam energy was selected so that the 80% isodose Line fell at 2cm below the bottom of the tumor bed cavity. The median survival time was 18 months in the patients treated with IORT and 8 months in the patients treated with postoperative whole brain irradiation (WBRT). The survival rate of the patients with IORT appeared not inferior to that of the patients with WBRT. IORT could save the length of hospital stay for the patient and could avoid unnecessary irradiation to the normal brain. IORT is one of the options in the treatment of brain metastases, particularly when the metastatic lesions is larger than 3 cm in diameter which is not suitable for radiosurgery using the gamma knife or linear accelerator.