Overview of Brain Tumors
It is a distressing experience for a patient to learn that he or she has been diagnosed with a brain tumor. However, each year researchers learn more about brain tumors and the best way to treat them, and the prognosis (predication about the future course of the disease) for many tumors is better today than it was even just a few years ago. This article may be helpful to your general understanding of the types of brain tumors, symptoms, diagnosis, and various treatment options. Keep in mind, though, that each brain tumor is unique. Your doctor will be the best source of information about your specific condition and its prognosis.
Classifying Brain Tumors
Brain tumors are abnormal growths of new and unnecessary cells in or on the brain. It is thought that tumors occur when genetic factors or environmental damage impair normal cells so that they multiply and divide rapidly. There are many different kinds of brain tumors, which are classified in different ways depending on where the tumor originates, how quickly the tumor grows, and how destructive the tumor is.
Brain tumors are usually classified as either benign or malignant. Benign tumors tend to be slow-growing clusters of cells that rarely spread. Tumors are classified as malignant when they grow aggressively, invade other parts of the body, cause damage to critical functions, or are life threatening. Malignant tumors are also known as cancerous.
Brain tumors that originate in the brain itself are called primary tumors. Primary brain tumors can start in the brain tissue, the brain lining (meninges), the skull, the nerves, or the pituitary gland. Tumors that originate somewhere else in the body and move into the brain are called metastatic tumors. Metastatic tumors are always malignant, since by definition they have invaded the brain from another part of the body. Very few primary brain tumors are benign, and even these tumors sometimes become malignant.
Tumors are graded to indicate their degree of malignancy using a system developed by the World Health Organization (WHO). This system classifies tumors into four groups (WHO Grade I through IV) depending on factors such as how abnormal the cells are, how quickly the tumor is growing, the potential for invasion or spread of the tumor, and the blood supply of the tumor. Grade I tumors are considered benign and usually have very good survival rates. Grade II tumors are slow growing, but sometimes invade nearby tissue and/or recur after treatment. Grade III tumors have more abnormal cells and grow faster than Grade II tumors. Grade IV tumors are the most malignant. They grow rapidly and spread widely.
Although these classifications can be helpful, diagnosis and classification of tumors does change. An early diagnosis may later be revised once a sample of the tumor is obtained and examined. In addition, as tumors grow they can be re-classified into higher-grade tumors.
The symptoms of brain tumors vary depending on the type of tumor and the individual, and may appear gradually if the tumor grows slowly. Symptoms are caused by tissue damage and pressure on the brain. Symptoms may also be caused by a buildup of fluid around the tumor, or the blockage of fluid by the tumor. Brain tumors often cause mental changes, which can produce symptoms such as problems with motor skills, problems with memory or communication, or changes in behavior or temperament. Headaches are another common symptom, especially headaches that are worse in the morning. Brain tumors may also cause seizures.