Brain Cancer Stages

When a person is diagnosed with a brain tumor, treatment will depend on several diagnostic factors, including:

• Classification: Type of tumor
• Grading: Degree of tumor malignancy
• Staging: Extent of invasiveness or metastasis.

Brain cancer, depending on the stage, may spread quickly through surrounding tissues. Understanding the tumor with respect to these variables allows the physician to predict the behavior of the mass, provide a prognosis and determine appropriate treatment options.

Brain Tumor Classification

Following a microscopic examination of tumor cells, pathologists are able to classify a brain tumor according to the type of cells from which it arises. For example, glial (non-neuronal cells in the brain) refers to the type of cells and tumors including:

• Astrocytes (astrocytomas)
• Ependymal cells (ependymomas)
• Oligodendrocytes (oligodendrogliomas).

The suffix "-oma" refers to a mass or tumor. These tumors can be further classified into subsets of tumor types, depending on the aggressiveness of the tumor and the patient's prognosis.

Grading and Brain Cancer Stages

The degree of malignancy of a tumor describes the growth rate of the cells. To determine the grade, a pathologist studies microscopic slides to evaluate prognostic factors, such as the cellular features and the percent of cells that are actively dividing. Grade I tumors are least malignant, or slowest growing, and Grade IV are the most malignant, or fastest growing masses.

Stages of Cancer

Staging of a tumor is a pathologist's way of describing a tumor, elaborating on the location, size and degree of metastasis (brain cancer spread). The different images from scans taken during the diagnosis show the oncologists where the tumor is located, if multiple masses exist and if surgery is an option. Once a neurosurgeon begins surgery, he collects more information by actually seeing how the tumor is interacting with surrounding tissues.

Stages are usually used to describe glial tumors, one of the most common types of brain tumor. This type of tumor rarely spreads outside of the central nervous system, so staging would only determine if it has spread to the spinal cord. Determination of a brain cancer stage may require a lumbar puncture to collect cerebrospinal fluid and search for abnormal cancer cells.

For example, a pathologist describing an astrocytoma—cancer that begins in the small, star-shape astrocyte cells of the brain and spinal cord—would use the following terminology:

• Grade I: Juvenile pilocytic astrocytoma is a well-defined, slow-growing brain tumor. Grade I tumors are benign and are usually removed via surgery.
• Grade II: Low-grade (or fibrillary) astrocytomas are less defined but still grow slowly.
• Grade III: Anaplastic astrocytomas tend to grow faster than grade I or II. Grade III (stage 3) cancer cells tend to invade surrounding tissue.
• Grade IV: Glioblastoma multiforme (GBM) tumors are the fastest-growing tumors and often spread into other tissue. The prognosis is poor, and surgery is usually used in conjunction with other treatments.

Resources

American Society of Clinical Oncology Staff. (2009). Brain tumor: Staging. Retrieved April 20, 2010, from the Cancer.net website: http://www.cancer.net/patient/Cancer Types/Brain Tumor'sectionTitle=Staging.

Burger, P. C. and Cohen, K. J. (n.d.). Classification, grading and staging of pediatric brain and spinal cord tumors. Retrieved April 20, 2010, from the Childhood Brain Tumor Foundation website: http://www.childhoodbraintumor.org/Burger_Cohen.html.

National Brain Tumor Society Staff. (n.d.). Tumor types. Retrieved April 20, 2010, from the National Brain Tumor Society website: http://www.braintumor.org/TumorTypes/.