Drugs and Cancer Risk
Despite the declines in the death rate over the last 20 years, cancer continues to be one of the most prevalent public health issues in the US. According to the National Cancer Institute 1:
- More than 68 million people will receive a cancer diagnosis in 2016 (with breast, lung, prostate, colon, and bladder cancer being the most common).
- About 40% of all people will be diagnosed with cancer in their lifetime.
- Nearly 600,000 people are expected to die from the disease in 2016 alone.
Risk factors for cancer are wide-ranging. Certain factors like age, family history, and hormonal fluctuations are outside of individual control. However, there are numerous other risk factors like diet and sun exposure that can be controlled, and a major preventable contributor to cancer is substance abuse 2.
According to the American Cancer Society, approximately 30% of all cancer deaths are attributed to tobacco use. Smoking causes 87% of lung cancer deaths in men and 70% of lung cancer deaths in women.
The risk does not end with lung cancer, however. Tobacco use has been linked to cancers of the 3, 4.
Tobacco smoke contains hundreds of harmful chemicals, and about 70 of them are known to cause cancer. Once ingested, the toxic effects of tobacco smoke can potentially damage every organ system in the body, which explains the vast variety of cancers triggered by use of the substance 4.
Because of this, there is no safe level of smoking, and there is no safe method of using tobacco products. Cigarettes are not the only method to confer these health dangers. You are also at risk if you use 4:
- Smokeless tobacco like chew, snuff, or snus.
Even electronic cigarettes have been found by some tests to have cancer-causing chemicals in the aerosol 22.
Fortunately, current smokers can significantly lower their risk for cancer by quitting. Cancer risk will significantly decrease within a few years after the last use 4.
According to the National Cancer Institute, about 3.5% of cancer deaths are caused by heavy alcohol use (more than 4 drinks per day/14 per week for men and more than 3 drinks per day/7 per week for women).
The risk of developing cancer from drinking alcohol increases with:
- Higher volume use.
- Use over a long period.
Heavy alcohol use is linked to higher levels of 5,6:
- Liver cancer.
- Esophageal cancer.
- Head and neck cancers, especially of the mouth, throat, and voice box.
- Breast cancer.
In the body, heavy use of alcohol is known to cause cancer in several ways including the following 5, 6:
- As the body processes alcohol, it becomes acetaldehyde – a fleeting, yet highly toxic carcinogen capable of damaging genetic material and causing cellular injury.
- Through a process called oxidation, alcohol triggers increased production of free radicals that damage DNA, proteins, and fats.
- Alcohol increases the levels of estrogen in the blood, which is linked to an increased risk of certain types of breast cancer.
- Alcohol hinders the body’s natural capacity for converting and absorbing helpful nutrients like folate (which may lower the risk of certain cancers).
- Drinking alcohol adds excess calories to the diet, increasing the risk of obesity, another risk factor for cancer.
Combining Alcohol and Tobacco
While both tobacco and alcohol individually raise cancer risk, smoking and drinking in combination heightens the risk exponentially. This is especially true for cancers of the:
- Oral cavity.
According to the American Cancer Society, alcohol functions as a solvent that enables other harmful toxins like tobacco smoke to more easily enter the cells in the upper digestive tract. This has been discussed as a possible explanation for why drinking and smoking in combination appears to significantly raise the risk of mouth and throat cancers. Additionally, alcohol makes it more difficult for the body to rid itself of certain toxins 6.
Though marijuana is commonly seen as safe and is increasingly legalized, it may be a factor in the development of certain cancers. There have been reports of increased incidents of cancers of the lungs, head, neck, and respiratory tract as a result of carcinogens and toxins 7.
Marijuana use also increases the risk of testicular cancer, especially in younger people. The evidence shows that males who smoke marijuana during adolescence have greater chances of developing a specific type of testicular cancer called non-seminomatous germ cell tumor 8. Studies indicate that marijuana smoke may contain a testicular carcinogen 21.
Anabolic steroids are a class of substances with androgenic, or testosterone-like effects, frequently used by those seeking to increase their muscle mass or improve performance in a physical activity or sport. Steroids also are linked to a number of unwanted effects including cancer.
Since the liver is the primary organ responsible for processing and clearing steroids from the body, this organ is subjected to damage in the form of 9:
- Liver tumors.
- Peliosis hepatitis.
With the hormonal changes triggered by steroid use, the formation of other cancers becomes more probable.
- In men, prostate cancer risk is increased 10, 11.
- In women, the danger of cervical and endometrial cancer grows 10.
Khat is a plant native to Eastern Africa and the Arabian Peninsula and used by 10 million people worldwide. In the US, the drug is used predominantly by people from or with cultural connections to countries like Somalia 12.
The plant can be chewed in a way similar to tobacco or brewed into a tea. Khat has been linked to a number of physical and mental health problems including cancer of the mouth. It appears that the risk increases when khat use is combined with alcohol and/or tobacco 13.
Other Cancer Risks
The above shows the specific substances of abuse that have been found to increase a user’s susceptibility to cancer. However, there are other factors that may also raise your risk if you’re abusing drugs.
The method of use, the mixture, or the manufacturing can indirectly expose the user and others to increased cancer risks.
Injection Drug Use
Most substances of abuse can be ingested in a variety of ways. Smoking, snorting, and swallowing all carry their own set of risks. One method of delivery that causes increased risk is injection.
Hepatitis B and hepatitis C are regularly transferred through sharing needles 14. This practice can spread disease by increasing the person’s contact with blood of infected individuals.
Without treatment, hepatitis can progress to cirrhosis and a particular form of liver cancer called hepatocellular carcinoma (HCC). Liver cancer causes more than 20,000 deaths each year in the US alone 14.
Illicit Drugs Containing/ Combined With Carcinogens
Toxins involved in the manufacturing or illicit distribution of certain drugs can increase cancer risk for those who handle the chemicals. There are several examples of this, including:
- Methamphetamine/crystal meth. Many toxic chemicals are used in the illicit manufacture of meth. One of these chemicals is the same carcinogen found in cigarettes and gasoline, benzene. The risk does not end there, however, as there are many chemicals used during meth production that are known to be toxic and cancer-causing 16.
- Cocaine. It is a common practice of cocaine dealers to add or mix in other substances to the drug in order to create more of the product and boost profits. At times, the product used to “cut” the cocaine can be carcinogenic. This was the case when phenacetin was found in some cocaine sold in the United Kingdom. Exposure to this substance is shown to increase the risk of cancer and kidney issues 17.
- MDMA. This substance poses risks associated with cancer that mirror issues associated with meth. During the manufacturing process, substances like safrole may be used 19. This substance has an unclear relationship to cancer in humans but has a history of producing cancerous tumors in rats 18.
Secondhand contact with certain substances may also increase cancer risk in some individuals. Two examples of particularly concerning secondhand exposures are:
- Secondhand smoke. According to the Centers for Disease Control and Prevention, 58 million nonsmokers were exposed to secondhand smoke between 2011 and 2012. This frequency of exposure has led to about 7,300 nonsmokers dying from lung cancer each year. Just like firsthand smoke, there is no safe level of contact with secondhand smoke. It is known to increase the risk of multiple forms of cancer 20.
- Meth lab exposure. Anyone living in or visiting a meth lab is at risk of being exposed to many dangers including chemical contamination from the carcinogenic toxins used during production. These toxins will be difficult to remove from the area with a simple cleaning, so many items around the house may stay contaminated for some time. Additionally, if the materials used during manufacturing are not disposed of thoroughly, others in the community may be put in harm’s way should they come in contact with these byproducts 16.
Reducing the Risk
The list of reasons to avoid abusing alcohol and other substances is long. The risk of cancer is rarely the first thing that comes to mind when you think of the perils of drug use; however, it is a major risk factor for several substances of abuse.
- National Cancer Institute. (2016). Cancer Statistics.
- National Cancer Institute. (2015. Risk Factors.
- American Cancer Society. (2014). Tobacco-Related Cancers Fact Sheet.
- National Cancer Institute. (2014). Harms of Cigarette Smoking and Health Benefits of Quitting.
- National Cancer Institute. (2013). Alcohol and Cancer Risk.
- American Cancer Society. (2014). Alcohol Use and Cancer.
- Substance Abuse and Mental Health Services Administration. (2015). Cannabis.
- National Institute on Drug Abuse. (2016). What are marijuana's effects on general physical health?
- Hoffman, J. R., & Ratamess, N. A. (2006). Medical Issues Associated with Anabolic Steroid Use: Are They Exaggerated? J Sports Sci Med, 5(2): 182–193.
- New York State Department of Health. (2008). Anabolic Steroids and Sports: Winning at any Cost
- National Institute on Drug Abuse. (2106). Anabolic Steroids.
- Drug Enforcement Administration. (2013). Khat.
- Kassie F, Darroudi F, Kundi M, Schulte-Hermann R, Knasmüller S. Khat (Catha edulis) consumption causes genotoxic effects in humans. (2001). Int J Cancer, 92(3):329-32
- National Institute on Drug Abuse. (2013). Viral Hepatitis-A Very Real Consequence of Substance Use.
- American Cancer Society. (2016). Benzene and Cancer Risk.
- Home Office. (2015). Fact Sheet: Cutting Agents.
- Department of Health and Human Services. (n.d.). Report on Carcinogens: Safrole.
- Drug Enforcement Administration. (n.d.). Advisories to the Public.
- Centers for Disease Control. (2015). Secondhand Smoke (SHS) Facts.
- Lacson, J. C., Carroll, J. D., Tuazon, E., Castelao, E. J., Bernstein, L., & Cortessis, V. K. (2012). Population-Based Case-Control Study of Recreational Drug Use and Testis Cancer Risk Confirms Association between Marijuana Use and Non-Seminoma Risk. Cancer, 118(21): 5374–5383
- NIDA for Teens. (n.d.). Tobacco, Nicotine, & E-Cigarettes.