Even when managed according to guidelines, approximately 14% of cancer patients have unrelieved pain or unacceptable side effects, and there is good evidence that patients still are not receiving optimal therapy. Implantable drug delivery systems (IDDS) administer small amounts of drugs directly to the spinal cord and reduce systemic narcotic exposure by a factor of 300 to one. In a large randomized trial of 202 patients with pain scores of 7.5 or higher, despite 200 mg or more of morphine or equivalent narcotics, IDDS gave better clinical success than comprehensive medical management (84.5% vs 70.8%, P=0.05). Pain scores were reduced by 52% versus 39%, drug toxicity scores were reduced by 50% versus 17%, and IDDS patients lived longer. Even the most refractory pain patients--those failed by a month of comprehensive medical management by experts--when subsequently provided with IDDS, had a 27% reduction in pain scores and a 50% reduction in drug side effects. Given multiple positive small cohort studies and a positive high-power randomized trial, IDDS should be considered as the best treatment for this population.