Overview of vitamin D actions in cancer

Throughout the past four decades, it has become evident that vitamin D has effects beyond calcium and bone metabolism. A wide variety of cells and tissues are affected by vitamin D. These targets include tumor cells, and the findings have led to a vast series of studies on the actions of vitamin D on regulation of tumor cell growth, treatment of cancer, and development of potent synthetic vitamin D analogs as inhibitors of tumor cell growth. Various specialized chapters in this book will discuss in detail the effects of vitamin D on specific cancer types. In this chapter, our goal is to set the stage by providing an overview of the history, current state of knowledge, and development of the field.