Pathophysiology of malignant bone pain

Introduction Currently, more than 10 million people are diagnosed with cancer every year, and by 2020, it is estimated that 20 million new cases will be diagnosed each year. In 2005, cancer caused 7.6 million deaths worldwide. In the United States, cancer is a major health problem, being the second leading cause of death. Currently, 25% of U.S. deaths are cancer related. Cancer-associated pain may be present at any time during the course of the disease, but the frequency and intensity of cancer pain tend to increase with advancing stages of cancer. In patients with advanced cancer, 62-86% experience significant pain, which is described as moderate to severe in approximately 40%-50% and as very severe in 25%-30%. Bone cancer pain is the most common pain in patients with advanced cancer; two thirds of patients with metastatic bone disease experience severe pain. Most common tumors, including those of the breast, prostate, thyroid, kidney, and lung, have a remarkable affinity to metastasize to bone. Currently, the factors that drive bone cancer pain are poorly understood; however, several recently introduced models of bone cancer pain not only are providing insight into the mechanisms that drive bone cancer pain, but are guiding the development of novel mechanism-based therapies to treat the pain and skeletal remodeling that accompany metastatic bone cancer. As analgesics can also influence disease progression, findings from these studies may lead to therapies that have the potential to improve the quality of life and survival of patients with skeletal malignancies.