Glioma – Diagnostics – Overview of Information and Clinical Research

Diagnosing glioma requires a careful combination of clinical evaluation, advanced imaging techniques, and laboratory analysis of tumor tissue to determine the exact type and characteristics of the tumor, which then guides treatment decisions and helps predict outcomes.

Introduction: Who Should Undergo Diagnostics and When

If you experience symptoms that suggest something may be affecting your brain or spinal cord, seeking medical attention promptly is important. Gliomas can cause a wide range of symptoms depending on where they develop and how quickly they grow. Common warning signs include persistent headaches that are often worse in the morning, unexplained nausea and vomiting, changes in vision such as blurred sight or double vision, difficulty with balance or walking, seizures that appear for the first time, personality changes or mood swings, confusion, memory problems, and weakness or numbness on one side of the body.^[1]^[2]

Anyone experiencing these symptoms should consult a healthcare provider, though it’s important to remember that these symptoms can also be caused by many other conditions that are not brain tumors. Gliomas are most commonly diagnosed in adults over the age of 65 and in children under age 12, though they can occur at any age.^[2] People with certain genetic conditions that run in families, such as neurofibromatosis (a disorder that causes tumors to grow on nerve tissue) or tuberous sclerosis complex (a condition that causes non-cancerous tumors in many organs), have a higher risk of developing gliomas and may benefit from more vigilant monitoring.^[8]

Early diagnosis matters because it allows treatment to begin sooner, which may help control the tumor and reduce symptoms. The diagnostic process helps doctors understand not just whether a tumor is present, but also what type it is, how aggressive it might be, and what treatment approach would work best for your specific situation.

Diagnostic Methods for Identifying Glioma

Diagnosing a glioma typically begins with a thorough physical examination and a neurological examination, which is a series of tests that check how well your brain and nervous system are working. During this exam, your doctor will assess your vision, hearing, balance, coordination, strength, and reflexes. If you have difficulty with any particular task, it might indicate that a brain tumor could be affecting that area of your brain.^[9]^[10]

Brain Imaging Studies

If your doctor suspects a glioma based on your symptoms and neurological exam, the next step is usually brain imaging. Magnetic resonance imaging, or MRI, is the most common and useful imaging test for detecting gliomas. This test uses powerful magnets, radio waves, and computer technology to create detailed pictures of the soft tissues inside your brain and spinal cord. An MRI can show the size, location, and some characteristics of a tumor. Often, you will receive an injection of a special dye called contrast material into a vein before the scan. This dye helps certain tissues show up more clearly on the images, making it easier for doctors to see the tumor’s edges and blood supply.^[9]^[10]

Another imaging test that may be used is a computed tomography scan, also called a CT scan. This test uses X-rays and computer technology to create cross-sectional images of your brain. While not as detailed as MRI for soft tissue, CT scans are faster and may be used in emergency situations or when MRI is not available or suitable for a patient.^[9]

In some cases, doctors may order a positron emission tomography scan, or PET scan. This type of imaging shows how active the cells in different parts of your brain are. Cancer cells typically show up as more active areas because they use more energy than normal cells. PET scans can help distinguish between tumor tissue and other changes in the brain, such as those caused by previous treatments.^[9]

⚠️ Important

While an MRI can suggest the presence of a glioma based on how the mass looks, it cannot confirm the diagnosis on its own. Other conditions, such as strokes, infections, or different types of tumors, can look similar on imaging scans. That’s why obtaining a tissue sample for examination under a microscope is essential to confirm the diagnosis and determine the specific type of glioma you have.^[19]

Biopsy and Tissue Analysis

To make a definitive diagnosis of glioma, doctors need to examine a sample of the tumor tissue under a microscope. This sample is obtained through a procedure called a biopsy. There are different ways to perform a biopsy depending on the location and characteristics of the tumor.^[9]

If your tumor can be surgically removed and you are healthy enough for surgery, the biopsy may be done during the operation to remove the tumor, which is called a resection. The surgeon will remove as much of the tumor as safely possible, and this tissue will be sent to the laboratory for analysis. In cases where surgery to remove the tumor is not advisable—perhaps because the tumor is in a difficult-to-reach location or removing it might damage important brain tissue—a stereotactic needle biopsy may be performed instead. During this procedure, a small hole is drilled in your skull, and a thin needle is carefully guided to the tumor using imaging technology. A small sample of tissue is removed through the needle for testing.^[9]^[10]

Once the tissue sample reaches the laboratory, it is examined by doctors who specialize in analyzing cells and tissues, called pathologists. They look at the tumor cells under a microscope to determine what type of glial cells they came from and how abnormal they appear. The pathologist also performs advanced tests on the tumor’s DNA to look for specific genetic changes, or mutations, in genes such as IDH (isocitrate dehydrogenase) and others. These molecular characteristics have become crucial in classifying gliomas and predicting how they might behave.^[9]^[10]

Tumor Grading and Classification

After examining the tissue sample, doctors classify the glioma using a grading system developed by the World Health Organization, or WHO. This system assigns a grade from 1 to 4 based on how much the cancer cells look like normal cells and how quickly the tumor is likely to grow. Grade 1 and 2 gliomas are considered low-grade, meaning they grow slowly and the cells look relatively normal. Grade 3 and 4 gliomas are called high-grade, meaning they grow quickly, the cells look very abnormal, and they are more aggressive.^[2]^[10]

Modern glioma classification relies heavily on molecular and genetic information. For example, gliomas are now categorized based on whether they have mutations in the IDH gene. A glioma described as “IDH mutant” has changes in this gene, while “IDH wildtype” means the gene is unchanged. Gliomas with IDH mutations generally have a better outlook than those without these mutations. Other important genetic markers include 1p/19q codeletion, which is found in certain types of gliomas called oligodendrogliomas and is associated with better responses to treatment.^[3]^[5]

The three main types of glioma in adults, based on the 2021 WHO classification, are astrocytoma, IDH mutant, oligodendroglioma, IDH mutant and 1p/19q codeleted, and glioblastoma, IDH wildtype. Each type behaves differently and requires different treatment approaches. Glioblastoma is the most aggressive form, classified as grade 4, and represents the most common type of malignant brain tumor in adults.^[5]^[10]

Diagnostics for Clinical Trial Qualification

Clinical trials are research studies that test new treatments or combinations of treatments to find better ways to help patients with glioma. The National Comprehensive Cancer Network recommends that people diagnosed with glioma explore whether there are clinical trials available that might be suitable for them.^[13]

To determine if you are eligible to participate in a clinical trial, you will need to undergo specific diagnostic tests that meet the trial’s requirements. These tests help researchers ensure that all participants in the study have similar disease characteristics, which makes the results more reliable and easier to interpret.

Standard Enrollment Criteria

Most clinical trials for glioma require recent brain imaging, typically an MRI scan performed within a certain timeframe before enrollment, often within a few weeks. This baseline scan allows researchers to accurately measure the tumor’s size at the start of the trial and track any changes during treatment. The imaging must often include contrast enhancement to clearly show the tumor’s borders.^[9]

Detailed pathology reports are essential for trial enrollment. The tumor tissue must have been analyzed not only for the basic cell type and grade but also for specific molecular markers. Many trials now require knowledge of IDH mutation status, 1p/19q codeletion status, and other genetic markers. Some trials specifically target patients whose tumors have certain mutations, such as alterations in the PDGFRA gene (platelet-derived growth factor receptor alpha), which can be treated with targeted drugs.^[15]

Blood tests are typically required to assess your overall health and ensure your organs are functioning well enough to tolerate the experimental treatment. These may include tests of liver function, kidney function, and blood cell counts. Your performance status—a measure of how well you can carry out daily activities—is also evaluated, as many trials only accept patients who are functioning relatively well.^[3]

Specialized Testing for Targeted Therapies

As researchers develop treatments that target specific genetic changes in tumors, clinical trials increasingly require specialized molecular testing. For instance, if a trial is testing a drug that targets tumors with PDGFRA mutations, participants must have their tumor tested specifically for these changes. This type of testing is done on the biopsy or surgical tissue using advanced laboratory techniques that examine the tumor’s DNA and proteins.^[15]

Some clinical trials may also require additional imaging beyond standard MRI, such as specialized MRI sequences that measure blood flow in the tumor or PET scans using specific tracers that highlight particular features of the cancer cells. These tests help researchers understand how the tumor is behaving and how it responds to the experimental treatment.

The screening process for clinical trials can take several weeks as all the required tests are completed and the results are reviewed. Your healthcare team can help you understand what tests are needed for specific trials and coordinate the necessary evaluations.

Prognosis and Survival Rate

Prognosis

The outlook for people with glioma varies greatly depending on several important factors. The type and grade of the glioma are the most significant predictors of outcome. Low-grade gliomas, such as grade 2 astrocytomas and oligodendrogliomas, typically have a better prognosis, with median survival times of five to seven years or longer. Many patients with low-grade gliomas can be controlled for extended periods with treatment. In contrast, high-grade gliomas, particularly glioblastoma, have a much more serious outlook, with median survival typically ranging from 12 to 18 months despite aggressive treatment.^[3]^[16]

Beyond the tumor type, several other factors influence prognosis. Younger age at diagnosis is associated with better outcomes—patients diagnosed in their 30s or 40s generally do better than those diagnosed after age 65. Better performance status, meaning you are able to carry out normal daily activities with little or no difficulty, also predicts longer survival. Molecular genetic factors have become critically important in determining prognosis. Gliomas with IDH mutations generally have significantly better outcomes than those without these mutations. Similarly, tumors with 1p/19q codeletion, which occurs in oligodendrogliomas, respond better to treatment and have longer survival times.^[3]^[8]

The extent of surgical removal also affects prognosis. Patients who have more complete tumor removal during surgery tend to have better outcomes than those who can only have partial removal or biopsy alone. However, the surgeon’s ability to remove tumor tissue safely depends on the tumor’s location—tumors in certain critical areas of the brain cannot be extensively removed without causing serious damage to important functions.^[16]

Survival Rate

Survival rates for gliomas vary widely based on the specific diagnosis. For glioblastoma, which is the most aggressive type, the five-year survival rate ranges from approximately 5 to 13 percent. Most patients with glioblastoma survive between 7.8 and 23.4 months after diagnosis with standard treatment, though some patients, particularly those who are younger with favorable molecular markers, may survive considerably longer.^[12]^[16]

Low-grade gliomas have substantially better survival statistics. Patients with grade 2 gliomas that have favorable molecular characteristics, such as IDH mutations and 1p/19q codeletion, often survive for many years—the median survival for these tumors can be a decade or more. However, many low-grade gliomas eventually transform into higher-grade tumors over time, which worsens the prognosis. Early detection and treatment of low-grade gliomas may slow or potentially prevent this transformation to more aggressive disease.^[10]^[16]

Grade 3 gliomas fall in the middle range, with median survival times varying from several years for anaplastic oligodendrogliomas with favorable markers to shorter periods for anaplastic astrocytomas without favorable molecular features. It’s important to understand that survival statistics are based on large groups of patients and represent averages. Individual outcomes can vary significantly based on the specific characteristics of your tumor, your overall health, and how well you respond to treatment.^[12]

#1 Clinical Trials Search in Europe