Opioid-responsive and opioid-non-responsive pain in cancer.

Cancer pain in general responds in a predictable way to analgesic drugs and drug therapy is the mainstay of treatment, successfully controlling pain in 70-90% of patients. The two major problem areas are pain associated with nerve damage, and 'incident' (movement-related) bone pain. Nerve damage pain tends not to respond well to morphine or other opioids. The difficulty with severe incident pain is that if the dose of opioid is titrated sufficiently to relieve the pain on weight-bearing or on movement and is then given regularly at this level, it is too much for the patient at rest. The patient may then experience excessive side-effects at rest, but still have pain on movement. Other examples of pain which may be resistant to treatment with opioid analgesics are bladder and rectal tenesmus, pancreatic pain, and pain associated with decubitus ulcers or other superficial ulcers subjected to pressure or shearing forces. Management of non-opioid-responsive pain may include a variety of treatments involving adjuvant analgesic drugs and non-drug measures.