Psychological dependence to an opioid drug is characterized by abnormal behavioral and other responses that always include a compulsion to take the drug to experience its psychic effects. Drug dependence is a pathological psychological response and is not physiological.
Several large studies of patients with cancer and pain have shown that, with the exception of a few patients with a past history of psychiatric disturbance or drug dependence, these patients do not become psychologically dependent. Even if it is anticipated that pain will be relieved by other means, opioid analgesics should not be withheld because of any concerns related to psychological dependence, although patients with a history of drug abuse should be managed carefully.
Woodruff R. Palliative medicine evidence-based symptomatic and supportive care for patients with advanced cancer. 4th ed. Oxford University Press, 2004. p. 107.