National Cancer Institute
U.S. National Institutes of Health |

NCI Home
Cancer Topics
Clinical Trials
Cancer Statistics
Research & Funding
About NCI
Substance Abuse Issues In Cancer (PDQ®)
Patient Version   Health Professional Version   En español   Last Modified: 09/02/2005



Prevalance Among the Physically Ill

Defining Terms for the Medically Ill

Risk in Patients Without Substance Abuse Histories

Risk in Patients With Substance Abuse Histories

Treatment of Patients With Substance Abuse Histories

Inpatient Treatment

Outpatient Treatment

Get More Information From NCI

Changes to This Summary (09/02/2005)

Questions or Comments About This Summary

About PDQ

Page Options
Print This Page
Print Entire Document
View Entire Document
E-Mail This Document
Quick Links
Director's Corner

Dictionary of Cancer Terms

NCI Drug Dictionary

Funding Opportunities

NCI Publications

Advisory Boards and Groups

Science Serving People

NCI Highlights
Virtual and Standard Colonoscopy Both Accurate

New Study of Targeted Therapies for Breast Cancer

The Nation's Investment in Cancer Research FY 2009

Cancer Trends Progress Report: 2007 Update

Past Highlights
You CAN Quit Smoking Now!
Prevalance Among the Physically Ill

Physical dependence
Substance abuse

Substance abuse is very uncommon among patients with cancer. The number of known patients with cancer who are substance abusers may be small because these patients do not seek medical help in hospitals, or they may not acknowledge to health care providers that they have a substance abuse problem.

Physical dependence

Physical dependence is defined as the occurrence of withdrawal symptoms when a drug is abruptly stopped, the dose is significantly reduced, or when a second drug is given that counteracts the actions of the drug to which the patient has developed a dependence. The dependence is not apparent until one of these actions occurs. When a patient with cancer is receiving an opioid drug for cancer pain, care is taken to avoid stopping the drug abruptly or prescribing other drugs that decrease or negate the effect of the opioid. Physical dependence on opioid pain medications does not seem to occur in patients with cancer. In these patients, once the pain disappears (usually through the effective treatment of the cancer), the pain medicine can be stopped without difficulty.


Tolerance to opioid pain medications may develop. Tolerance is the need to take increasingly larger doses of medication to relieve pain symptoms. Among patients taking opioid drugs for medical reasons, tolerance has not been shown to lead to drug addiction or drug abuse problems.

Substance abuse

Substance abuse is the use of a drug in any manner that does not conform to the physician's orders or the use of any illegal drug.


Addiction is the use of a substance in a manner that is out of control, compulsive, used in increasing amounts, and is continued despite the risk of harm. A patient who uses opioids to relieve cancer pain may become physically dependent on the drugs, but is not described as being addicted to them.

These terms are generally used in association with people who do not have a medical illness. The terms are not entirely appropriate to use to describe medically ill people who are using drugs therapeutically.

Back to Top

< Previous Section  |  Next Section >

A Service of the National Cancer Institute
Department of Health and Human Services National Institutes of Health