High-grade gliomas are malignant brain tumors that recur despite surgery, chemotherapy, or conventional radiotherapy. Since median overall survival for glioblastoma multiforme was reported to be 14.6 months with standard treatment (surgery and temozolomide) [1], temozolomide has often been used after surgery. For recurrent high-grade glioma, bevacizumab with stereotactic radiotherapy (SRT) is also safe and well tolerated [2]. Recently, stereotactic radiosurgery (SRS), SRT, and intensity-modulated radiation therapy (IMRT) have advanced as new standard additional irradiation modalities for the first recurrence of high-grade glioma [[3], [4], [5], [6], [7], [8]] However, high-grade gliomas eventually recur. Repeated high precision radiotherapy may be a further salvage treatment for patients with recurrent high-grade glioma, even after radiotherapy for recurrence.

Tomotherapy (Tomotherapy Inc., Madison, WI, USA) involves a computed tomography (CT) - image guided radiation therapy (IGRT) system and a helical intensity-modulated radiation therapy (IMRT) delivery system. The IGRT co-registers daily pretreatment megavoltage (MV) CT scans to the initial planning CT scans to ensure accurate patient setup. The IMRT uses an MV linear accelerator (Linac) mounted on a continuously rotating gantry, a platform that moves the patient continuously through the radiation beam, detectors for MV CT imaging on the gantry opposite the radiation source, and a 64 multi-leaf collimator (51 times per gantry) that dynamically modulates the radiation beam [9]. Simultaneous integrated boost (SIB) technique by tomotherapy can deliver a homogeneous brain dose and a conformal dose to the tumor [10]. The tomotherapy equipped with the various latest functions may offer repeated irradiation to control two or more recurrences of high-grade glioma effectively, while sparing normal brain tissue and limiting side effects.

This preliminary study examined whether repeated tomotherapy can be performed for patients with repeated recurrences as additional salvage treatment with minimum symptomatic adverse events.