There are many ways to define pain. A useful definition is from pain expert Margo McCaffrey, MSN,RN, FAAN: “Pain is whatever the experiencing person says it is, and exists whenever he says it does.” The International Association for the Study of Pain says it is “an unpleasant sensory and emotional experience in association with actual or potential tissue damage, or described in terms of such damage.” Whatever definition you prefer, pain is a sensation that hurts, and it has both physical and emotional aspects to consider.
Pain, which can be caused by the disease itself or by treatments, is common in people with cancer, although not all people with cancer will experience pain. Approximately 30% to 50% of people with cancer experience pain while undergoing treatment, and 70% to 90% of people with advanced cancer experience pain Lesage P. and Portenoy RK. Cancer Control; Journal of the Moffitt Cancer Center 1999;6(2):136-145.
Pain can be acute or chronic: Acute pain usually starts suddenly, may be sharp, and often triggers visible bodily reactions such as sweating, an elevated blood pressure, and more. Acute pain is generally a signal of rapid-onset injury to the body, and it resolves when pain relief is given and/or the injury is treated.
Chronic pain lasts, and pain is considered chronic when it lasts beyond the normal time expected for an injury to heal or an illness to resolve. Chronic pain, sometimes called persistent pain, can be very stressful for both the body and the soul, and requires careful, ongoing attention to be appropriately treated. Chronic cancer pain can be successfully treated by about 95% of people with the drug and non-drug therapies that are currently available [[Wood, editor. Pharmacologic Treatment of Cancer Pain. New Engl J Med 1996;335:1124-1132]]. Along with chronic cancer pain, sometimes people have acute flares of pain when not all pain is controlled by the medication or therapy. This pain, usually called breakthrough pain, can also be controlled by medications.