Definition: Chancer is a type of cancer that affects the blood vessels, particularly in the brain and spinal cord. It can be caused by exposure to certain chemicals or toxins, such as asbestos, which can damage the blood vessels and lead to the development of chancers. Chancers are usually diagnosed when they reach stage 3 or higher on the National Cancer Institute (NCI) cancer registry. Treatment for chancers typically includes radiation therapy, chemotherapy, and possibly surgery if it is indicated.