Radiation Therapy (RT) remains the most effective post-operative treatment for high-grade glioma (HGG). 90% of patients that are diagnosed with HGG will experience recurrence soon after initial RT. Stereotactic Radiosurgery (SRS) has been utilized in the management of glioma as a boost after conventional RT. Currently, median survival for HGG has remained stagnant at around 14.6 months, however current research justifies the use of a boost of 10Gy to 20Gy via SRS to increase survival. This review aims to determine the efficacies of dose escalation via salvage SRS to manage recurrent HGG, whilst not increasing risks of radiation induced toxicities.
A retrospective review was carried out from 7 separate studies; all patients underwent conventional RT in conjunction with an SRS boost for HGG after local recurrence. All patients underwent IMRT or 3D-Conformal initial RT of up to 60Gy and then underwent an SRS boost of 10-20Gy. Various fractionation schedules for SRS were implemented.
The primary end point was median survival and radiation induced toxicities. From the time of initial RT to local failure was overall 7 months. The SRS boost given at the time of local failure, increased survival on average by 10 months. Various low-grade toxicities were noted such as nausea and fatigue, however minimal grade 3 toxicities such as radiation-induced necrosis were noted.
Overall, this review highlights the promising advances within radiotherapy and in turn that SRS increases survival for recurrent HGG. Techniques such as SRS have been proven to increase survival by safely delivering a higher dose to the tumour, whilst sparing critical structures. Greater information relating to radiation-induced toxicities, caused by dose escalation, is needed due to possible under reporting by patients themselves.