Cancer pain classification

About three quarters of patients with advanced cancer experience pain. Most of these have multiple pains. Causes of pain fall into four broad categories: the cancer itself, related to the cancer +/- debility, related to treatment, concurrent disorder. From a neuropathological perspective, pain is either nociceptive or neuropathic. This distinction is important because neuropathic pain is generally less responsive to analgesics than nociceptive pain. Recognition of functional muscle pain is important. Patients with severe chronic pain do not necessarily look in pain because of the absence of autonomic concomitants. Whatever the cause, pain is a "somatopsychic' experience.