Cancer, Drugs, and Alcohol | Research & Encyclopedia Articles

Medical researchers are constantly trying to determine which substances cause cancer. Among the substances they study are alcohol and drugs—both legal, prescription medications and illegal drugs of abuse. Another area of concern is the treatment of cancer patients who are or have been substance abusers.

There are several ways to study whether a substance is a "carcinogen," or a substance that causes cancer.

1. Cancer cells have certain abnormalities in their cell structures. Cells can be grown in a test tube to see if these cell-structure abnormalities develop.
2. The substance can be given to animals to see if cancers result.
3. Doctors and medical researchers can analyze the course of a disease in a human patient.
4. Researchers can compare the outcomes in a group of people who use a certain substance to outcomes in those who do not.

Identifying carcinogens is complex and difficult, partly because of the long time delay between the use of a carcinogen and the appearanceof cancer symptoms. It can take as long as thirty years for those symptoms to appear. This is why early studies of new medications are rarely successful at identifying carcinogens. Also, cancers can have many causes other than carcinogenic drugs, such as environmental, nutritional, and genetic factors. It is often difficult to separate one cause from another.

Alcohol. Research conducted on animals does not show that alcohol alone causes cancer. However, the body metabolizes alcohol to produce acetaldehyde, an enzyme that has been shown to be carcinogenic. Animals who were exposed to alcohol in combination with known carcinogens had higher rates of several kinds of cancerous tumors than did animals only exposed to the known carcinogen.

Studies show that alcoholics are more likely to have cancers of the digestive tract than nonalcoholics. The risk for cancer increases with the amount of alcohol consumed. Overall, it has been estimated that as many as 10 percent of all cancer deaths are due to alcohol.

Illicit Drugs. The role of illicit drugs as a cause of cancer is still unclear. Research reports show that heavy marijuana users sometimes get cancers in the respiratory tract, primarily the lungs. Cocaine users, who usually take the drug by inhaling it, can get cancers of the nasal passages. Opium smokers have increased rates of cancer of the esophagus.

Cancer patients have used marijuana to reduce the nausea that chemotherapy treatment sometimes produces. Marijuana may also be used to provide pain relief. However, opinion varies sharply about whether a drug that is an illegal source of abuse should be used for these medical purposes. Doctors often give cancer patients morphine or other opioids, drugs known to have the potential for addiction, to control pain. Patients with no history of substance abuse very rarely become addicted to these drugs. In contrast, treatment is complicated for patients who have abused opioid drugs in the past. A history of substance abuse may shorten a cancer patient's life expectancy, and drugs used to manage pain may not be as effective.

Cocaine; Law and Policy: Drug Legalization Debate; Opiate and Opioid Drug Abuse; Tobacco: Medical Complications.

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