What is the relationship between cancer and substance abuse?

Cancer Risks

Certain substances of abuse, including tobacco, marijuana, alcohol, methamphetamine, cocaine, and heroin, present special risks for the development of cancer.

Tobacco

Tobacco is a well-known carcinogen, and its use is the leading cause of preventable illness and death in the United States. In addition to causing lung, throat, and mouth cancer, it has been associated with cancers of the nasal cavity, esophagus, stomach, pancreas, breast, kidney, bladder, and cervix. Nicotine, which is contained in tobacco leaves, is highly addictive; however, it is not known to be carcinogenic. Nicotine is a vasoconstrictor (blood vessel constrictor), so it increases the risk of cardiovascular disease.

The National Cancer Institute has revealed the following statistics related to cancer and tobacco use in the United States:

• Cigarette smoking causes an estimated 443,000 deaths each year, including approximately 49,400 deaths from exposure to secondhand smoke.

• Lung cancer is the leading cause of cancer-related death among both men and women; 90 percent of lung cancer deaths among men and approximately 80 percent of lung cancer deaths among women are caused by smoking.

• Persons who smoke are up to six times more likely to have a heart attack than are nonsmokers, and the risk increases with the number of cigarettes smoked. Smoking also causes most cases of chronic lung disease.

• In 2009, about 21 percent of adults were cigarette smokers.

• Nearly 20 percent of high school students smoke cigarettes.

Smoking (or chewing) tobacco markedly increase the risk of cancers of the oral cavity (mouth, lips, and tongue). One of the effects of tobacco is that it weakens the immune system, which not only increases the risk of cancer but also increases the risk of infection. Aside from its relationship to cancers of the oral cavity, chewing tobacco also increases the risk of many other cancers and health problems.

Marijuana

Smoked marijuana and smoked tobacco are chemically similar; thus, like cigarettes, the greatest health hazard of marijuana is from smoking the substance. The psychoactive component of marijuana leaves, delta-9-tetrahydrocannabinol (THC), is a relatively safe drug.

Smoked marijuana, however, is a health risk. Thorough scientific analyses have identified at least six thousand of the same chemicals in marijuana smoke present in tobacco. The chief difference between the two plants is that marijuana contains THC and tobacco contains nicotine. Moreover, one of the most potent carcinogens in tobacco smoke, benzo[a]-pyrene, is present in larger quantities in marijuana smoke.

Another factor increasing the carcinogenic risk of marijuana is in the way it is inhaled; marijuana smokers frequently inhale and hold the smoke in their lungs, which increases the amount of tar deposited in the respiratory tract by a factor of about four. Approximately 20 percent of regular marijuana smokers (those who smoke three to four joints a day) have problems with chronic bronchitis, coughing, and excess mucus.

An alternative to smoking marijuana is ingesting it in pastries, drinks, and lollipops. Marijuana leaves also can be baked into brownies and other desserts. Ingested marijuana has no known carcinogenic effect; however, it still has a psychoactive effect, which can result in myriad problems, including social problems, traffic accidents, and dependence.

A problem with ingesting rather than smoking marijuana is that the digestive process markedly slows the onset of psychoactive effects. This makes ingesting less attractive to users of the substance; furthermore, because the onset of marijuana’s effect is slowed through ingestion, a large amount of the substance must be consumed, ultimately resulting in an unusually high level of THC in the body.

Alcohol

The combination of alcohol abuse and tobacco use markedly increases the risk of cancers of the oral cavity. Approximately 50 percent of cancers of the mouth, pharynx (throat), and larynx (voice box) are associated with heavy drinking. Even in nonsmokers, a strong association exists between alcohol abuse and cancers of the upper digestive tract, including the esophagus, the mouth, the pharynx, and the larynx.

Alcohol abuse, either alcoholism or binge drinking, also has been linked to pancreatic cancer, particularly in men. The risk has been reported to be up to six times greater than in men who do not abuse alcohol. A possible association may exist between alcohol abuse and other cancers, such as liver, breast, and colorectal cancers. It has been estimated that 2 to 4 percent of all cancer cases are caused either directly or indirectly by alcohol abuse. Alcohol abuse, like cigarette smoking, suppresses the immune system, which in turn increases the risk of developing cancer. These persons often do not seek treatment until the cancer is well advanced.

Methamphetamine

A number of different chemical processes can be used to make methamphetamine
; most of the processes include the use of volatile organic compounds, which are emitted gases, some of which have carcinogenic effects. Also, other toxic substances can be produced through the production of methamphetamine. Some of these substances are carcinogenic. Specifically, pancreatic cancer has been associated with methamphetamine use.

Cocaine and Heroin

Cocaine itself is not associated with a cancer risk; however, substances added to cocaine are carcinogenic. One example is phenacetin, which not only can cause cancer but also can induce kidney damage. Heroin and other opiates have no known carcinogenic properties. However, like cocaine, heroin may contain additives that are carcinogenic.

Substances Used and Abused by Persons with Cancer

Cancer, particularly in advanced stages, can cause extreme pain; thus, persons with cancer are often prescribed opiates to lessen their pain. Marijuana too is used by persons with cancer for pain relief and to reduce the side effects of chemotherapy.

Opiates

An opiate is a drug derived from opium, which is the sap of the opium poppy (Papaver somniferum). Opium has been used by humans since ancient times. Many opiates are on the market, including morphine, meperidine hydrochloride (Demerol), hydromorphone hydrochloride (Dilaudid), hydrocodone (Vicodin), and oxycodone (Oxycontin). Heroin is an excellent analgesic, but it is not prescribed for pain relief because of its highly addictive properties compared with other opiates. Another property of opiates is tolerance, which results in the need for increasingly higher doses to achieve the same effect.

Tolerance and addiction are not a major concern for a terminally ill person with cancer but they are a concern for persons with cancer that is in remission or cured. Some of these persons have “exchanged” their cancer for a drug addiction. After completing a drug rehabilitation program, these persons are at high risk to resume the use of opiates. Researchers believe that drug relapse is caused by the stress associated with cancer, combined with the ready availability of psychoactive drugs, both prescription and illegal.

Marijuana

Cancer and its treatment with chemotherapy is associated with side effects such as nausea, vomiting, anorexia (loss of appetite), and cachexia (muscle wasting). Marijuana is effective in reducing these symptoms; therefore, it has been recommended for persons with cancer.

The opinion of scientists at the National Cancer Institute, however, is that pharmaceuticals are available that are superior to marijuana in their effects. These pharmaceuticals include serotonin antagonists such as ondansetron (Zofran) and granisetron (Kytril), used alone or combined with dexamethasone (a steroid hormone); metoclopramide (Reglan) combined with diphenhydramine and dexamethasone; methylprednisolone (a steroid hormone) combined with droperidol (Inapsine); and prochlorperazine (Compazine).

Medical marijuana
legislation is a controversial topic in the United States. Despite the controversy, medical marijuana outlets (dispensaries) are increasing in number throughout the country. Their incidence depends on state and federal regulations. Many states have adopted marijuana statutes that are much more liberal than federal statutes.

Although there are legitimate medical uses for marijuana for persons with cancer and other conditions (such as glaucoma), many of the medical marijuana outlets supply the product to almost anyone for any reason.

Bibliography

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