It has been suggested that neuropathic pain, which accounts for 15% 20% of pain problems that are difficult to manage, is opioid-resistant and that opioid drugs should not be used in this patient population. In fact, studies exploring reasons for inadequate pain treatment have identified that up to two thirds of cancer pain patients have some contribution of neuropathic pain to their global pain syndrome ; when the concept of bone pain as a neuropathic pain syndrome is included, this number Jumps again. Studies involving cancer patients with both nociceptive and neuropathic pain, as well as controlled studies of nonmalignant neuropathic pain, demonstrate the variable responsiveness of neuropathic pain to opioid analgesics. Hence, the contribution of neuropathic pain must be considered when assessing opioid responsiveness