Substance abuse in cancer patients who do not have histories of substance abuse is exceptionally rare. Opioids and other controlled substances can be prescribed judiciously for symptom management, without concern about misuse. When problematic drug-taking behavior is manifested by such patients, it is often the result of poor pain control. However, many people with cancer have a history of drug abuse or live among those who do. They have special needs that are often underappreciated because this problem is overlooked.[1] Nearly one-third of the population of the United States has used illicit drugs, and an estimated 6% to 27% have a substance abuse problem of some type.[2,3,4,5] The abuse of prescription opioids has grown rapidly since the mid-1980s and is now as frequent as the abuse of cocaine.[6] Because of the prevalence of substance abuse and the association between drug abuse and some types of cancer,[1] problems related to abuse and addictions are encountered in palliative care settings.

The population of patients who have histories of substance abuse or addiction is extremely heterogeneous, and the status of each patient will affect concerns central to his or her palliative care. Patients who are actively abusing alcohol, illicit drugs, or prescription drugs present problems distinct from those experienced by patients in drug-free recovery or patients in methadone maintenance programs. Appropriate diagnosis of substance abuse may be challenging because of the variability in abuse behaviors over time, the changes in comorbid physical and psychosocial factors that influence drug abuse, and the problems inherent in the nomenclature of drug abuse in the physically ill.

Patients who have histories of substance abuse present many clinical problems. Clinicians must control and monitor drug use in all patients. Compliance with treatments for the underlying disease may be so poor among cancer patients who are actively abusing drugs that the substance abuse actually shortens life expectancy by preventing the effective administration of primary therapy. Prognosis may also be altered by the use of drugs in a manner that negatively interacts with therapy or predisposes the patient to other serious morbidity.

Active or past substance abuse also may weaken social support networks. Among these supports is the patient's relationship with the treatment team. Lack of mutual trust can characterize the relationships between substance-abusing patients and members of the treatment team. Concerns about drug abuse may lead clinicians to doubt the veracity of the history divulged by the patient, the report of symptoms, and compliance with therapy. A desire to build trust may lead clinicians to hide these concerns from the patient. Patients with histories of substance abuse may sense the mistrust, question the team's good will, and have negative expectations that become self-fulfilling prophecies. Mistrust can disrupt assessment, management, and follow-up and can result in the failure of therapies intended to improve quality of life.