Cancers are caused by an accumulation of mutations that alter the activity of genes involved in controlling cell birth, growth, and death. Some of these errors are inherited, but most occur after birth, triggered by environmental carcinogens or by mistakes during cell division.  If cancer is likened to a car speeding out of control, cancer-causing mutations are like broken brakes, a stuck accelerator, or an inept mechanic. Dr. Vogelstein explains that although there are numerous kinds of cancer, all stem from alterations that allow cell division to outstrip cell demise. From the Series:HHMI’s Understanding Biomedical Research Series