Table 1.

Major advantages and disadvantages of GMB diagnosis and treatment modalities.

GBM Diagnosis Techniques
Technique	Advantages	Disadvantages
Molecular Markers	Some molecular markers are useful to predict the response to chemotherapy. In the future more specific and reliable molecular markers could be used as diagnostic and prognostic markers and/or as targets for therapy (personalized medicine).	Currently, there are no molecular markers for GBM diagnosis. Molecular markers are measured only in a tumor biopsy. Expression levels of a specific molecular marker may vary between two GBM patients or with tumor progression.
Non-Invasive Brain Imaging Diagnosis	Provides images and maps (including 3D images) of the brain in a non-invasive manner. Allows for more accurate GBM diagnoses.	Some techniques may increase cancer risk (as a result of radiation). The intravenous injection of exogenous agents -needed for imaging- can trigger unwanted side effects. Most of the equipments are very expensive.
Tumor Biopsy	Histologic analysis of the tumor remains the gold standard for the diagnosis of GBM and other tumor types.	Tumor heterogeneity, non-specific morphologic features, and tumor sampling may reduce the diagnosis value. Sometimes, the histological analysis is not conclusive and the procedure must be repeated. All types of brain biopsies may result in swelling or bleeding on the brain.

GBM Treatment and Post-treatment Techniques
Technique	Advantages	Disadvantages
Tumor Resection	Extent resection of GBMs increases OS and PFS. Craniotomy and debulking offers a modest survival advantage over biopsy. The use of 5-ALA enables more tumor resection and increases PFS.	Invasive. Surgical and Anesthesia risks involved. May increase OS and PFS with a tax in quality of life.
Chemotherapy	Temozolomide (Temodar) in combination with radiotherapy is the gold standard for GBM treatment. Several drugs to target specific cell survival pathways I cancer cells are under investigation and/or in clinical trials.	Most chemotherapeutic agents affect also normal cells and cause side effects. Most chemotherapeutic drugs do not cross the BBB. Most patients become resistant to chemotherapy. Inefficacious when GBM is in advanced stages (highly infiltrated).
Radiotherapy	Non invasive high field energy that kills cancer cells. The technology has improved in such a way that it allows the radiation beam to focus better at the tumor tissue and decrease damage to surrounding non-neoplastic areas.	Affects normal brain tissue and significantly lower in efficacy if used without Temodar concomitantly. Induce other side effects: hair loss, sickness, tiredness, worsening of the brain tumor symptoms.
Intraoperative Radiotherapy	Delivers more specifically a dose of radiation to the tumor bed intraoperatively.	Involves a craniotomy, debulking of tumor and the surgical risks that are involved. Not available everywhere.
Electric Fields	Tumor Treatment Fields affect rapidly dividing tumor cells. OS comparable to current Chemotherapy and XRT.	Battery dependent hardware and multiple components to the system. Not indicated for newly diagnosed GBM patients.
Post-treatment Imaging	Non invasive follow up on tumor progression and staging of disease.	Confounding factors of pseudoprogression and radionecrosis. Require specialized techniques and expensive equipment.