Problem 2RCQ: How does pressure at the bottom of a body of water relate to... How does pressure at the bottom of a body of water relate to the weight of water above each square meter of the bottom surface? Chapter , Problem is solved.
The mutations that cause carcinoid tumors often affect the MEN1 gene, the same gene responsible for most familial neuroendocrine tumors and neuroendocrine cancers. But not much is known about exactly what causes these gene changes. Doctors do know that carcinoid tumors start out very small and grow slowly. When patients have parts of their stomach or small intestine removed to treat other diseases, taking a close look under the microscope often shows small groups of neuroendocrine cells that look like tiny carcinoids.
As with tumors elsewhere in the body, the exact cause of most brain tumors is unknown. The following factors have been proposed as possible risk factors for primary brain tumors, but whether these factors actually increase an individual's risk of a brain tumor is not known for sure. 1  Radiation to the head. 2  An inherited (genetic) risk. 3  HIV infection.