"I find it impossible to describe how targeted cancer treatments work without mentioning what it is they target. And when I try to explain what it is they target, I find myself going back to the beginning and explaining where cancers come from, what faults they contain, and why they behave as they do. And, to explain that, I need to explain concepts such as DNA damage, oncogenes, tumor suppressor genes, and the hallmarks of cancer cells. In recent years, we've also made great progress in using a patient's immune system to treat cancer using immunotherapy. When explaining how immunotherapies work, I find it useful to offer at least a brief description of our immune system and the ways in which cancer cells and white blood cells interact. Armed with this knowledge, various strategies to use the immune system to destroy cancer cells begin to make sense. In this chapter, my goal is to bring together much of this background knowledge. I hope it will provide you with a useful foundation that enables you to understand individual targeted therapies and immunotherapies that I mention in later chapters"-- Provided by publisher.