Understanding Your Glioblastoma Pathology Report

When you have glioblastoma, a pathology report documents vital information about your brain tumor, which helps your healthcare team decide on the best treatment path. But trying to make sense of the technical language can feel confusing.

“Pathology and radiology (MRI) reports are written by doctors for doctors,” says Fernando Santos, MD, a neuro-oncologist at Orlando Health in Florida. “That is why it is not uncommon for patients to feel overwhelmed by the official medical terms frequently used in such reports.”

Some people wait until their provider can translate their reports, Dr. Santos says: “Your doctor can walk you through what everything means in a way that is clear and relevant to your specific situation.”

Although it’s always important to have your oncologist and care team explain the details of your pathology report so that you can understand them, it also may help to know a bit more about your report beforehand.

What Does ‘Grade 4’ Mean?

“Glioblastoma, which is, unfortunately, always grade 4, is a very difficult disease to treat,” says Edjah K. Nduom, MD, a neurosurgeon and professor in the department of neurosurgery at Emory University School of Medicine in Atlanta.

“This is then followed by 6 to 12 months of oral chemotherapy,” he says.

Key Biomarkers

“Molecular markers play a significant role in helping doctors choose the best treatment tailored specifically to the cancer type,” Santos says. “They also allow us to predict how the tumor will behave after being exposed to treatments.”

Your glioblastoma pathology report may include a number of common biomarkers.

IDH Mutation Status

Tumors with an IDH mutation grow slowly, but most glioblastomas don’t have this mutation, which makes them more aggressive, says Nitesh V. Patel, MD, a brain and tumor neurosurgeon and the codirector of the neurosurgical oncology program at Hackensack Meridian Jersey Shore University Medical Center in Neptune, New Jersey.

“This [biomarker] is one of the strongest predictors of prognosis,” Dr. Patel says.

MGMT Methylation

TERT Promoter

“[But] we do not make any changes to our treatment based on the presence or absence of TERT promoter mutation,” he says.

EGFR Amplification

“Currently, there are no EGFR-inhibitors (also known as targeted therapy) that have been FDA-approved for use in glioblastoma,” says Santos, adding that clinical trials are underway on oral chemotherapy options for people with this mutation.

Mismatch Repair

Mismatch repair (MMR) deficiency is when your cells have a difficult time noticing errors when they duplicate themselves, which creates mutations, Nduom says.

BRAF Mutations

Ki-67 Labeling Index

Mesenchymal Epithelial Transition Proto-Oncogene

Neuron-Glial Antigen 2

Hyaluronic Acid Receptor CD44

Common Pathology Report Terms

• Hemisphere Each half of your brain, left and right, is called a hemisphere.
• Lobe Each hemisphere is divided into lobes: frontal, parietal, temporal, and occipital.
• Gyri and Sulci Gyri are the ridges and sulci are the grooves on your brain’s surface.
• Corpus Callosum This is an area in the middle of your brain that lets your two hemispheres communicate.

• Astrocyte/Astrocytic A type of brain cell

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• Chromosomes Strands of DNA
• Giant Cell A glioblastoma subtype (other subtypes include small cell, epithelioid, sarcomatous, and gliosarcoma)
• Hemorrhage Bleeding from an injured blood vessel

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• Heterogeneous Sample containing different parts, like blood and tumor tissue
• Hyperchromatic/Hyperchromasia A darker-looking cell center

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• Immunohistochemical Stains Additives used to find specific biomarkers in the sample, causing it to change color

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• Infiltrating Cancer cells growing into nearby tissues

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• Mitotic Cells preparing to divide

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• Multinucleated Cells with more than one nucleus, typically found in giant cell glioblastomas

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• Necrosis Injury and death of cells

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• Neoplasm Abnormal growth (the tumor)
• Nucleus The part of the cell that carries DNA
• Pleomorphic Varied sizes and shapes of cancer cells and other structures (not uniform)

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If your pathology report feels too overwhelming, focus on the final diagnosis, tumor grade, and key markers, Patel says.

“And remember, you don’t have to interpret it alone — your care team will guide you,” he says.

Even if you feel you understand your report, it’s vital to talk it over with your provider.

“Establishing a trusting and confident relationship with your care team is one of the most important factors of this journey,” Santos says. “It is important that patients feel comfortable reaching out to their providers whenever they have a question or concern about their medical condition.”