Mechanisms of Cancer Pain

This chapter focuses on neurobiological mechanisms of cancer pain. In human patients, tumor metastasis is the most common cause of pain associated with cancer. The pain caused by cancer can be classified into two categories-cancer-related pain and cancer-unrelated pain. The chapter summarizes current knowledge related to peripheral mechanisms of cancer pain, and then provides an overview of the central mechanisms, particularly at the level of the spinal cord, that contribute to this chronic pain state. It also summarizes some of the peripheral mediators released at the tumor site that are responsible for cancer pain. Cancer itself can induce pain both peripherally and centrally. There are many substances or mediators released during cancer growth that induce and maintain cancer pain. In addition, cancer pain may occur indirectly via chemotherapy, and coexisting painful conditions may be present. Understanding these complex mechanisms is necessary to effectively control and manage pain.