Outlook for Varying Types of Glioma

Prognosis, or recovery outlook, for glioma is highly variable and depends on the tumor grade, size, and location.

Factors such as age, extent of tumor removal during surgery, and overall mental and physical function of patients at the time of diagnosis are also useful indicators of prognosis.

In short, the prognosis of a brain tumor estimates the length of time an average person lives after diagnosis.

Since these estimates are created using population statistics, outliers (people living more or less than the estimate) do exist. Here, we will discuss many of the factors involved in determining the prognosis, or recovery outlook, for patients diagnosed with glioma.

One of the most important considerations regarding prognosis is how aggressive a patient’s tumor is. This is often determined under the microscope by the pathologist using a specimen from a biopsy and is described in detail in our glioma overview section.

The World Health Organization (WHO) classifies glioma in 4 grades: Grade I through Grade IV. The higher the grade, the more invasive and malignant a particular glioma is. In general, a slow-growing and less invasive tumor usually carries a better prognosis than a fast-growing and invasive tumor.

Specific outlooks by tumor grade are included below:

• Grade I (pilocytic astrocytoma): These tumors generally have an excellent prognosis. Several studies have reported up to a 95% 5-year survival rate, which means that 95% of patients are living after 5 years of being diagnosed.
• Grade II (astrocytoma, oligodendroglioma, mixed oligoastrocytoma): These tumors are more unpredictable and can progress into Grade III and IV tumors even with treatment. The infiltrative nature of Grade II as well as Grade III and IV tumors make recurrences more likely.
• Grade III (anaplastic astrocytoma, anaplastic oligodendroglioma, anaplastic mixed oligoastrocytoma): These tumors are more aggressive and have a reasonable risk of recurrence. Some patients may live longer after surgical resection and adjuvant (supplemental) treatments such as radiation and chemotherapy.
• Grade IV (glioblastoma): These tumors are the most aggressive, cancerous, and generally have worse outcomes. Survival is often limited, with most patients living up to 1 or 2 years. Long-term survival is very rare.

It may be helpful to think of gliomas on a spectrum with low-grade gliomas being at one end of the spectrum with the best survival rates. Low-grade gliomas consist of WHO Grades I and II.  They often have an excellent prognosis and thus tend to have a longer survival rate.

Several types of low-grade glioma carry survival rates that can surpass 15 years. For example, a pilocytic astrocytoma often has survival rates greater than 15 years (assuming the patient undergoes treatment).

In fact, an overwhelming majority (just under 95%) of patients with pilocytic astrocytoma are living 5 years after diagnosis.

On the other end of the brain tumor spectrum are those that are very invasive and malignant. Tumors in this category carry a poor survival time, and while treatment can help to prolong survival, this is usually and unfortunately measured in months rather than years.

Glioblastoma is the most common malignant brain tumor and makes up about 14% of all primary tumors within the brain.

Glioblastomas can grow very quickly. Rapid expansion of the tumor does not allow accommodation by healthy brain tissue, as is the case with slower-growing tumors.

Many patients with glioblastoma will not survive longer than 1 year. Unfortunately, it is estimated that less than 7% of patients with glioblastoma will survive to 5 years after their diagnosis.

This difference in survival time will undoubtedly impact both the patient and their family a great deal. It is very important for the patient (and their loved ones) to have support from one another, friends, the medical team, chaplains, and other members of the care team.

Aggressive tumors often require aggressive treatments to slow progression and maximize survival time. Many patients elect to undergo treatment so they can have more time with their loved ones.

Nevertheless, treatment options such as surgery, chemotherapy, and radiation have side effects that can impact quality of life. The decision to undergo treatment must be informed.

While risks and benefits should be carefully considered, the patient retains the ultimate decision about the treatment goals and may change these goals at any time.

Radiation therapy after tumor resection can lead to cognitive impairment, including difficulty thinking, memory issues, and reductions in processing speed.

While radiation is aimed at eliminating a patient’s tumor, it also can damage healthy tissue within the brain.

When tissues are damaged, they can trigger an inflammatory response. This response can cause swelling (edema) and a shift of fluid into the brain. This inflammatory response, or edema, can aggravate previous symptoms or cause more symptoms to arise.

Many patients will also undergo chemotherapy. Chemotherapy is often widely distributed throughout the body.

Chemotherapy also carries a risk of cognitive impairment as well as other side effects that vary depending on the type of chemotherapy that is used.

Age is an important factor to consider when trying to predict a patient’s prognosis and long-term glioma survival. 

Generally speaking, the age group with the best prognosis with brain cancer is young adults (ages between 15 and 39). This age group tends to do better than children under 15 and adults older than 40.

The glioma survival rate for children with low-grade tumors is relatively high, often exceeding 90% for a 5-year period. High-grade gliomas, such as glioblastomas, have a more guarded prognosis, with survival rates ranging from 20% to 30% over five years. Early diagnosis and advancements in treatment have significantly improved outcomes in recent years. 

This age group sees varied outcomes based on the grade of the glioma. Low-grade gliomas generally have favorable prognoses, with some patients achieving long-term survival. Approximately 26% of adolescents and young adults aged 15 to 29 survive for over five years.

However, higher-grade gliomas have poorer outcomes, with median survival rates around 1 to 2 years. 

In most cases, adults older than 40 have a worse prognosis when compared to individuals younger than 40. This is primarily due to the aggressive nature of high-grade tumors and the presence of other health conditions in this age group. 

The median survival time for older patients with glioblastoma is approximately 9 to 12 months. Lower-grade gliomas in older adults also tend to progress more rapidly than in younger patients. Ultimately, treatment may be challenging due to the lower tolerance of aggressive therapies in older adults. 

It is important to remember that these trends do not guarantee specific outcomes. Many factors should be considered when predicting outcomes. Every patient’s case is unique.

People with gliomas with a genetic marker called MGMT methylation generally experience a better glioma tumor survival rate. MGMT (O6-methylguanine-DNA methyltransferase) methylation makes the tumor cells more responsive to certain chemotherapies, enhancing the effectiveness of the treatment and potentially improving glioma survival rate. 

MGMT is a gene responsible for repairing damaged cells, including fixing glioblastoma cells destroyed by chemotherapy. The methylation of MGMT hinders this repair mechanism, resulting in a higher mortality of tumor cells.

It’s normal to feel anxious and distressed after receiving a diagnosis. Finding the right support can significantly enrich emotional well-being and quality of life. 

Support groups provide a space to share experiences, exchange practical tips, and build a community with others in similar situations. Organizations like the National Brain Tumor Society and the American Brain Tumor Association offer various resources, including online and in-person support groups, educational materials, and caregiver resources. Engaging in these groups can help reduce feelings of isolation and give you the information you need to navigate the journey ahead.

• A recent diagnosis of glioma is very challenging for patients and family members alike.
• While it may be informative to understand which risk factors are associated with prolonged survival, it is more important to recognize that each patient is different.
• Health-related quality of life and maximizing quality time with loved ones are important when considering whether to initiate or remain under treatment. This is particularly critical with aggressive treatments which are more likely to come with side effects.
• In any case, a detailed and frank discussion with your care team is critical so that both the patient and physician have a clear understanding of the goals of care.

• National Brain Tumor Society
• American Brain Tumor Association
• Brain Tumor Foundation
• Children's Brain Tumor Foundation
• Pediatric Brain Tumor Foundation
• Glioblastoma Foundation