Glioblastoma

🧠 Standard of Care & Symptoms

Glioblastoma (also known as Glioblastoma Multiforme or GBM) is the most common and aggressive malignant primary brain tumor in adults. It is characterized by rapid growth and diffuse infiltration into the surrounding brain tissue.

• Presentation: Key clinical features.
  • *Headaches:* Often worse in the morning or when lying down, due to elevated intracranial pressure (ICP) from tumor mass effect.
  • *Neurological Deficits:* Progressive weakness or numbness on one side of the body (hemiparesis), difficulty speaking (Aphasia), visual changes, or balance issues.
  • *Seizures:* New-onset seizures in an adult are a key presenting symptom, caused by tumor-induced cortical irritation.
  • *Cognitive Decline:* Changes in personality, memory loss, confusion, or apathy due to selective frontal or temporal lobe involvement.

🧬 Diagnostics & Molecular Pathology

Diagnosis relies on contrast-enhanced neuroimaging and definitive histopathological analysis following surgical biopsy or resection.

• Diagnostic Markers: Key criteria.
  • Brain MRI with Contrast: DWI, T2/FLAIR, and T1 post-contrast sequences typically show a thick, irregularly ring-enhancing mass with a central hypointense necrotic core and surrounding vasogenic edema.
  • MGMT Promoter Methylation Status: Deployed as a key predictive biomarker. Patients with a methylated *MGMT* gene promoter have silenced expression of the DNA repair enzyme MGMT, rendering the tumor highly sensitive to alkylating chemotherapy (Temozolomide).
  • IDH Mutation Status: GBMs are classified based on mutation of the Isocitrate Dehydrogenase (*IDH*) gene. IDH-wildtype accounts for 90% of cases (primary GBM, poorer prognosis), whereas IDH-mutant (secondary GBM) carries a relatively better prognosis.

Pathophysiology of Glioblastoma Growth

The aggressive clinical behavior of GBM is driven by key cellular and molecular mechanisms:

• Microvascular Proliferation: GBM cells secrete high levels of Vascular Endothelial Growth Factor (**VEGF**), inducing the rapid formation of abnormal, leaky blood vessels to sustain tumor growth.
• Pseudopalisading Necrosis: Rapid tumor cell division outstrips the oxygen supply, causing localized necrosis. Keratinocytes and astrocytes migrate away from these hypoxic zones, forming characteristic "pseudopalisades" surrounding necrotic centers.
• EGFR Amplification and EGFRvIII Mutation: Over 50% of GBMs show amplification of the Epidermal Growth Factor Receptor (**EGFR**) gene. The **EGFRvIII** mutation results in a constitutively active receptor that continuously drives downstream oncogenic PI3K/Akt/mTOR pathways, promoting cell survival and invasion.

💊 Therapeutic Interventions & TTFields

The standard of care for newly diagnosed glioblastoma involves maximal safe surgical resection followed by concurrent chemoradiation.

The Stupp Protocol

• Surgical Resection: The primary goal is the maximal safe removal of tumor mass to relieve mass effect and obtain tissue for molecular profiling.
• Concurrent Chemoradiation: Following surgery, patients undergo 6 weeks of focal brain radiotherapy (60 Gy total) combined with daily oral **Temozolomide (TMZ)** chemotherapy.
• Adjuvant Temozolomide: Following a 4-week break, patients receive 6 additional cycles of monthly adjuvant Temozolomide (5 days of dosing every 28 days).

Adjuvant Technologies

• Tumor Treating Fields (TTFields - Optune): A non-invasive regional therapy that applies low-intensity, alternating electric fields to the scalp via transducer arrays. Deployed during the adjuvant TMZ phase, TTFields disrupt mitotic spindle formation in dividing cancer cells, slowing tumor progression.
• Cerebral Edema Management: High-dose corticosteroids like **Dexamethasone** are used to control peritumoral edema, and anti-VEGF monoclonal antibodies (**Bevacizumab**) are indicated for refractory edema and recurrent disease.

🔬 Active Clinical Trials

Clinical trials are currently investigating EGFRvIII-targeted CAR-T cells, peptide vaccines, and novel tyrosine kinase inhibitors.

🗺️ Next Steps After Diagnosis

If you or a loved one has recently been diagnosed with Glioblastoma, coordinate these clinical steps:

1. Confirm Pathology and Biomarkers: Review surgical pathology report to confirm MGMT methylation status and IDH mutation status.
2. Schedule Chemoradiation: Coordinate with a neuro-oncologist and radiation oncologist to begin the 6-week Stupp Protocol chemoradiation window (usually 3 to 6 weeks post-surgery).
3. Discuss Optune (TTFields): Contact an Optune educator or neuro-oncology team to arrange training for Tumor Treating Fields during the maintenance phase.
4. Screen for Clinical Trials: Explore clinical trials immediately post-resection, as many immunotherapy and vaccine trials require enrollment prior to beginning radiotherapy.

❓ Patient FAQ

Q: What is the significance of the MGMT promoter methylation status?
A: MGMT is a DNA repair enzyme that repairs the damage caused by Temozolomide (TMZ) chemotherapy. If the *MGMT* promoter is methylated (silenced), the tumor cells cannot repair this damage, making the chemotherapy significantly more effective. Unmethylated patients may still receive TMZ, but are prime candidates for clinical trials exploring alternative treatments.

Q: Can Optune be used at the same time as chemotherapy?
A: Yes. Tumor Treating Fields (Optune) are FDA-approved to be used concurrently with maintenance Temozolomide chemotherapy. The transducer arrays are worn directly on the shaved scalp and must be kept in place for at least 18 hours per day for maximum efficacy.