Combined Salvage Therapies for Recurrent Glioblastoma Multiforme: Treatment Options in Multifocal and Multicentric Patterns of Recurrence

Despite the advancement made in the fields of neurosurgery, neuro-oncology, medical oncology, and radiation oncology, patients with recurrent high grade gliomas represent a unique challenge to the treating physicians [1,2]. Gliomas have the ability to disseminate along established CNS routes, such as white matter tracts, cerebrospinal fluid, or local invasion [3]. Multifocal appearance according to Budka et al. consists of tumors separated by white matter tracts within the same hemisphere, whereas multicentric glioma consists of tumors in opposite hemispheres or separated by the tentorium [4]. Tumor dissemination can serve as a prognostic marker at the time of the primary diagnosis [5] but a multifocal and multicentric recurrence of the glioblastoma into the surrounding and distant brain tissue is also associated with rapid clinical decline.