More than 10 million people are diagnosed with cancer (other than skin cancer) every year, and this number is expected to increase to 15 million per year by 2020. In 2005, cancer caused 7.6 million deaths worldwide. Cancer is a major health problem in the United States: 25% of US mortalities are related to cancer, making it the second leading cause of death.
Despite the increasing prevalence of cancer, improvements in the detection and treatment of most types of cancers have resulted in significantly increased survival rates. Pain is the first sign of cancer for many patients, most of whom will experience moderate to severe pain during the course of their disease and even into survivorship. Cancer-associated pain can be present at any time during the course of the disease, but the frequency and intensity of cancer pain tends to increase as the disease progresses, such that 62% to 86% of patients with advanced-stage cancer experience significant amounts of cancer-induced pain. If cancer patients and survivors, given their increasing life spans, are to remain functional, integrated, and contributing members of society, novel mechanism-based therapies will need to be developed to reduce cancer-related pain.
Cancer pain may arise from different processes: by direct tumor infiltration or involvement, as a result of diagnostic or therapeutic surgical procedures (eg, biopsies, resection), or as a side effect or toxicity related to therapies used to treat cancer (eg, chemotherapy, radiation therapy).