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Drug and Alcohol Misuse and Cancer Risk

What Causes Cancer?

Despite declines in the death rate over the last 20 years, cancer continues to be one of the most prevalent public health issues in the U.S. According to the National Cancer Institute:1

  • About 1,806,590 new cases of cancer would be diagnosed in 2020.
  • An estimated 606,520 people would die from cancer in 2020.
  • Also in 2020, prostate, lung, and colorectal cancers accounted for about 43% of all cancers diagnosed in men. The 3 most common cancers for women were breast, lung, and colorectal cancer, and these accounted for an estimated 50% of all new cancer diagnoses.

Risk factors for cancer are wide-ranging. Certain factors like age, family history, and hormonal changes are outside of an individual’s control. However, there are several other risk factors—such as smoking, diet, and sun exposure—that can be controlled, and a major preventable contributor to cancer is substance misuse.2

Tobacco/Cigarette Smoking

According to the American Cancer Society, approximately 30% of all cancer deaths are attributed to tobacco use.3 Smoking causes about 80% of lung cancers and lung cancer deaths in the United States.3 The risk does not end with lung cancer, however. Tobacco use has been linked to cancers of the:3,4

  • Mouth.
  • Throat.
  • Larynx.
  • Esophagus.
  • Stomach.
  • Colon.
  • Rectum.
  • Pancreas.
  • Liver.
  • Kidneys.
  • Bladder.
  • Cervix.
  • Blood.

Tobacco smoke contains hundreds of harmful chemicals, and about 70 of them are known to cause cancer.4 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 of exposure to these health dangers. You are also at risk if you use:4

  • Smokeless tobacco like chew, snuff, or snus.
  • Pipes.
  • Cigars.
  • Hookahs.

Fortunately, current smokers can significantly lower their cancer risk 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.5 For women, heavy alcohol use is considered more than 4 drinks per day or 8 drinks per week.5 For men, it is defined as more than 5 drinks per day or 15 drinks per week.5

A person’s 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 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 an individual’s risk of certain cancers).
  • Drinking alcohol adds excess calories to the diet, increasing a person’s risk of obesity—another risk factor for cancer.

How alcohol causes 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.
  • Pharynx.
  • Larynx.
  • Esophagus.

According to the American Cancer Society, alcohol functions as a solvent that enables other harmful toxins like tobacco smoke to enter the cells more easily in the upper digestive tract. This has been discussed as a possible explanation for why drinking and smoking in combination appears to significantly raise a person’s 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.7 Marijuana use has been found to increase the risk of testicular cancer, especially in younger people.8 The evidence shows that males who smoke marijuana during adolescence have greater chances of developing a specific type of testicular cancer called a non-seminomatous germ cell tumor.8 Studies indicate that marijuana smoke may contain a testicular carcinogen.8

Anabolic Steroids

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 several 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.
  • Adenomas.
  • Peliosis hepatitis.

With the hormonal changes triggered by steroid use, the formation of other cancers becomes more probable.

  • In men, prostate and testicular 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 United States, the drug is used predominantly by people from or with cultural connections to countries like Somalia.12

The plant can be chewed like tobacco or brewed into a tea. Khat has been linked to several physical and mental health problems, including cancer of the mouth. It has been found that the risk increases when khat use is combined with alcohol and/or tobacco.13

Other Cancer Risks

The information above shows the specific substances of misuse that have been found to increase a user’s susceptibility to cancer. However, there are other factors that may also raise an individual’s cancer risk if they are misusing drugs.

The method of use, the mixture, and the manufacturing can indirectly expose the user and others to increased cancer risk.

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 injecting drugs.

Hepatitis B (HBV) and Hepatitis C (HCV) are regularly transferred through sharing needles.14 This practice can spread disease by increasing a person’s contact with the blood of infected individuals. In 2017, there were an estimated 44,700 new cases of acute HCV.14

Without treatment, hepatitis can progress to cirrhosis and a particular form of liver cancer called hepatocellular carcinoma (HCC).

Illicit Drugs Containing/Combined With Carcinogens

Toxins involved in the manufacturing or illicit distribution of certain drugs can increase cancer risk among 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 methamphetamine. One of these chemicals is the same carcinogen found in cigarettes and gasoline, benzene.15
  • Cocaine. It is a common for cocaine dealers to add other substances to the drug 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 a person’s risk of cancer and kidney issues.16
  • MDMA. Methylenedioxymethamphetamine (MDMA) poses risks associated with cancer that mirror issues associated with methamphetamine. During the manufacturing process, substances like safrole may be used.17 This substance has an unclear relationship to cancer in humans, but it has a history of producing cancerous tumors in rats.18

Secondhand Risk

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 (CDC), 58 million nonsmokers were exposed to secondhand smoke (based on 2019 data).19 This frequency of exposure has led to about 7,300 nonsmokers dying from lung cancer each year.20 Just like firsthand smoke, there is no safe level of contact with secondhand smoke.
  • 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 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.

Reducing the Risk of Cancer

The list of reasons to avoid misusing alcohol and other substances is long. The risk of cancer may not be the first thing that comes to mind when you think of the perils of drug use. However, it is a major risk factor when it comes to several substances of abuse. To learn about treatment options to end the use of alcohol, tobacco, or any other substance, please call American Addiction Centers (AAC) free at .

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