Transdermal fentanyl for chronic cancer pain: detailed case reports and the influence of confounding factors.

Patients were entered into an open label study to evaluate the efficacy of transdermal fentanyl as an analgesic for chronic cancer pain. The clinical course of 3 patients is described as well as an emphasis on the apparent influence of confounding factors, i.e., factors unique to each patient that appeared to affect that individual's analgesic requirements. Our anecdotal clinical experience suggests that transdermal fentanyl is an acceptable, efficacious, and safe means of pharmacologic management for patients with chronic cancer pain. Our results reinforce the concept that cancer pain is a dynamic, multiply determined process and that, as a result, the effects of a single intervention are difficult to analyze.