Brain Tumors

The term "brain tumor" includes any tumor within the skull: tumors that are within the substance of the brain and those that are outside the substance of the brain but within the skull.  In addition, there are tumors that start within the skull and tumors that come from someplace else (like the lung or breast, for example) and metastisize to the brain or the coverings of the brain.
When brain tumors are malignant, they are classified as cancerous. There are 130 different types of brain tumors, making diagnosis and treatment very difficult. More than 612,000 people in the U. S. are living with a diagnosis of a primary brain or central nervous system tumor.
Tumors that start in the brain are called primary brain tumors. Often, tumors found in the brain have started somewhere else in the body and spread to one or more parts of the brain. These are called metastatic brain tumors (or brain metastases). Metastatic brain tumors are more common than primary brain tumors.
The types of cancer that commonly spread to the brain are melanoma and cancer of the breast, colon, lung, and unknown primary site. The types of cancer that commonly spread to the spinal cord are lymphoma and cancer of the lung, breast, and prostate. About half of metastatic brain and spinal cord tumors are caused by lung cancer. Leukemia, lymphoma, breast cancer, and gastrointestinal cancer may spread to the leptomeninges (the two innermost membranes covering the brain and spinal cord).
Brain tumors are the deadliest form of childhood cancer. Brain stem gliomas, atypical teratoid/rhabdoid and glioblastoma multiforme have survival rates of less than 20 percent. Non-malignant/benign brain tumors can kill children if their location in the brain prevents surgical removal or other curative treatments. Pediatric brain tumors aren't like those in adults. Children's brain tumors require specific research and different treatments. Even though survival rates for some childhood brain tumors have increased over the past 30 years, survivors often suffer from lifelong side effects of treatments such as surgery, radiation and chemotherapy.

Removing adult tumors through surgery

If doctors think there may be a brain tumor, a biopsy may be done to remove a sample of tissue. For tumors in the brain, the biopsy is done by removing part of the skull and using a needle to remove the tissue sample. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are found, the doctor may remove as much tumor as safely possible during the same surgery. After the surgery, a pathologist checks the cancer cells to find out the type and grade of brain tumor. The grade of the tumor is based on how abnormal the cancer cells look under a microscope and how quickly the tumor is likely to grow and spread. A CT scan or MRI may be used to find out if any cancer cells remain after surgery.
The following tests may be done on the tumor tissue that is removed:

• Immunohistochemistry study: A laboratory test in which a substance such as an antibody, dye, or radioisotope is added to a sample of cancer tissue to test for certain antigens. This type of study is used to tell the difference between different types of cancer.

• Light and electron microscopy: A laboratory test in which cells in a sample of tissue are viewed under regular and high-powered microscopes to look for certain changes in the cells.

• Cytogenetic analysis: A laboratory test in which cells in a sample of tissue are viewed under a microscope to look for certain changes in the chromosomes.

Sometimes a biopsy or surgery cannot be done safely because of where the tumor formed in the brain or spinal cord. These tumors are diagnosed based on the results of imaging tests and other procedures.