MEDLINEPLUS: <p>There are two main types of brain cancer. Primary brain cancer starts in the brain. Metastatic brain cancer starts somewhere else in the body and moves to the brain. Brain tumors can be benign, with no cancer cells, or malignant, with cancer cells that grow quickly. </p><p>Brain tumors can cause many symptoms. Some of the most common are</p><ul><li> Headaches, usually worse in the morning </li><li> Nausea and vomiting</li><li> Changes in your ability to talk, hear or see</li><li> Problems with balance or walking</li><li> Problems with thinking or memory </li><li> Muscle jerking or twitching</li><li> Numbness or tingling in arms or legs</li></ul><p>No one knows the exact causes of brain tumors. Doctors can seldom explain why one person develops a brain tumor and another does not.</p><p style="font-weight:bold;font-style:italic;">NIH: National Cancer Institute</p>,NCI: A primary or metastatic malignant neoplasm affecting the brain.