Treatment of Newly Diagnosed HGGs
Anaplastic astrocytomas carry a 2-year survival rate of up to 50% and have a strong tendency to progress to GBM in approximately 2 years. Glioblastoma multiforme accounts for the majority of adult brain tumors and, without treatment, the median overall survival in patients with GBM is reported to be 9 weeks. The current standard of care for newly diagnosed GBM with temozolomide and radiation therapy increases median survival to 14.6 months. The temozolomide and radiation combination therapy is well tolerated and increases 2-, 3-, and 5-year survival to 27.2%, 10.1%, and 9.8%, respectively. Cytoreduction by resection has also been shown to increase survival in patients with HGG compared with biopsy alone. Several retrospective studies have shown increased median survival with gross-total resection (GTR) of HGGs.[12,37,42,61] This has been corroborated by a prospective study of 124 newly diagnosed patients with HGG, which demonstrated that GTR was associated with longer survival and better quality of life than biopsy alone.
Surgical adjuvants such as intraoperative MRI[15,29,36,66] and 5-aminolevulinic acid[46,70,71] are associated with greater extent of HGG resection and improved progression-free survival. Hence, the current standard treatment algorithm for newly diagnosed HGGs is GTR of the enhancing tumor, followed by temozolomide and radiation therapies.[52,77] Although chemoradiation therapy is generally well tolerated, surgery is not always a viable option. In certain circumstances, the patient may be too ill to tolerate a craniotomy for tumor resection. In other situations, the tumor may be in a location involving eloquent cortex or deep-seated structures, in which case resection would lead to significant neurological deficits. For these patients, current treatment typically includes biopsy for diagnosis followed by chemoradiation. Therefore, novel technologies such as LITT aimed at maximal local cytoreductive therapy would potentially have a significant impact on overall outcomes for these patients. The main treatment indication for the use of LITT in newly diagnosed HGG has been for patients with inoperable brain tumors or those who are not candidates for open surgery due to advanced age and/or medical comorbidities. Common tumor locations that are ideal for up-front LITT include deep gray matter regions (e.g., thalamus and basal ganglia), the corpus callosum, and the insula (Fig. 2A and B)—providing cytoreductive therapy while minimizing the morbidity of the surgical approach.
Radiographic results after stereotactic laser ablation of brain tumors. A: Preoperative (left) and postoperative (right, 3 months post-LITT) T1-weighted axial MRI of brain obtained with Gd contrast showing thalamic GBM treated de novo with LITT. Postoperative image shows stable ring enhancement at the edge of treatment zone. Reproduced with permission from Neurosurgery. Hawasli AH et al: Magnetic resonance imaging-guided focused laser interstitial thermal therapy for intracranial lesions: single-institution series. Neurosurgery 73(6):1007–1017, 2013. B: Preoperative (left) and postoperative (right, 5 months post-LITT) T1-weighted axial MRI of brain obtained with Gd contrast showing GBM in right corpus callosum treated with LITT. C: Preoperative (left) and postoperative (right, 3 months post-LITT) T1-weighted axial MRI of brain obtained with Gd contrast showing treatment of recurrent frontal lobe GBM.
Neurosurg Focus. 2014;37(6):e1 © 2014 American Association of Neurological Surgeons