Brain Tumors: Primary - Causes

Prognosis

About 13,000 people die from cancerous brain tumors each year. Recent advances in surgical and radiation treatments have significantly extended average survival times and can reduce the size and progression of malignant gliomas.

The survival rates in people with brain tumors depend on many different variables:

• Type of tumor (such as astrocytoma, oligodendroglioma, or ependymoma)
• Location and size of tumor (these factors affect whether or not the tumor can be surgically removed)
• Tumor grade
• Patient's age
• Patient's ability to function
• How far the tumor has spread

Grading Tumors

Malignant primary brain tumors are classified according to tumor grade. Grade I is the least cancerous, and Grades III and IV are the most dangerous. Grading a tumor can help predict its growth rate and tendency to spread. Grading is based on the appearance of the tumor cells as seen under a microscope.

---

---

• Lower-grade (I and II) tumor cells are well defined and almost normal-shaped. Some primary low-grade brain tumors are curable by surgery alone, and some are curable by surgery and radiotherapy. Low-grade tumors tend to have the most favorable survival rates and high-grade the least. However, this is not always the case. For example, some low-grade II gliomas are at very high risk for progression.
• Higher-grade (III and IV) tumor cells are abnormally shaped and are more diffuse, which indicates more aggressive behavior. (High-grade brain tumors usually require surgery, radiotherapy, chemotherapy, and possibly investigational treatments.)

In tumors that contain a mixture of different-grade cells, the tumor is graded according to the highest-grade cells in the mixture, even if there are very few of them.

Survival Rates

Survival rates for brain tumors vary widely depending on the type of tumor and other factors, including age. Survival rates tend to be highest for younger patients and decrease with age.

Patients with some types of tumors have relatively good survival rates. Five-year survival rates for patients with ependymoma and oligodendroglioma are, respectively, 86% and 82% for people ages 20 - 44, and 69% and 48% for patients ages 55 - 64. Glioblastoma multiforme has the worst prognosis with 5-year survival rates of only 14% for people ages 20 - 44, and 1% for patients age 55 - 64.