Meningioma is evaluated with a grading scale, rather than the standard staging scale that is used to classify most other solid tumors. This is primarily because the traditional staging scale places a heavy emphasis on lymph node involvement and metastatic spread, two things that do not commonly occur with meningiomas. Instead, to evaluate these typically benign and slow-growing tumors, the World Health Organization created a specific meningioma grading system that focuses on the appearance of the cells and the composition of the tumors.
The meningioma grading system uses a scale of 1 to 3, with the lower numbers representing less-aggressive cancers. The grades of meningioma, and the characteristics for each, are:
- Grade 1 – These tumors are benign; they tend to grow at a very slow rate and have distinct borders. The cells look very much like normal cells when viewedbeneath a microscope.
- Grade 2 – These tumors are usually also considered benign, but may slowly spread to nearby tissues. The cells look slightly abnormal when viewed beneath a microscope.
- Grade 3 – These tumors are malignant, and the cancerous cells divide rapidly and can spread into healthy brain tissue. The cells look very abnormal when viewed beneath a microscope.
Almost 90 percent of all meningiomas are classified as grade 1. Another 7 to 8 percent are classified as grade 2 and the remaining 2 to 3 percent are classified as grade 3.
Meningioma grading has a significant impact on treatment. Because grade 1 meningiomas are benign, they might not require surgery unless they are causing pain or discomfort. On the other hand, high-grade meningiomas can potentially spread throughout the body, so a combination of surgery and radiation therapy is often recommended.
At Moffitt Cancer Center, meningioma grading is a process that is collaboratively completed by a team of experienced oncologists, radiologists and pathologists. These highly trained medical professionals work together to ensure the thorough evaluation of a patient’s diagnostic tests, which lays the groundwork for our oncologists to provide highly individualized treatment.