Integrating pain metrics into oncology clinical trials.

Cancer-related pain is highly prevalent and often severe, and as a result is often one of the defining experiences for patients with malignancy. Patients and patients' families almost always live with the ever-present reality that cancer treatment and progression may be accompanied by pain. For patients nearing the end of life, most fear that their final days will be spent living with the terrible effects of the disease, the most important of which is pain. Despite this, there is far less systematic research on the mechanisms of cancer-related pain or on the development of new agents to reduce or eliminate pain in cancer patients compared with research to combat the disease itself. Further, even when the focus of research is treatment of the tumor, the effects of anticancer treatments on pain are often underreported in publications and other forums. To illustrate the relative drought in the cancer pain control area, there have been no new drugs approved for cancer-related pain in recent years. A number of methodologic and logistical challenges that hinder the ability to assess pain response in clinical trials are discussed in this article. Possible ways to address these challenges are also discussed.