In this book, "Selenium: A Silent Warrior Against Prostate Cancer", we explore the complex and multifaceted role of selenium, an essential trace element, in the fight against prostate cancer. Selenium, although present in small quantities in our bodies, plays a crucial role in many of the body's protective functions.We begin with an introduction to selenium and its importance to human health. Next, we look in detail at how selenium can help prevent prostate cancer, how it influences the development of prostate cancer, and how it can be used in the treatment of this disease.In addition, we explore selenium's role in detoxification against heavy metals, which are sometimes cancer provoking factors. We also discuss the challenges and opportunities associated with the use of selenium in combinatorial therapy.Finally, we conclude with a discussion of future prospects for research into selenium and prostate cancer. The aim is to understand and exploit the potential of selenium in the fight against prostate cancer.