Cancer and Addiction: Does Substance Abuse Increase the Risk of Cancer?

Can Drugs or Alcohol Cause Cancer?

While it’s difficult to determine exactly what caused someone’s cancer, science has revealed a host of risk factors that can increase the chances of developing it. Some forms of substance misuse are clear risk factors for multiple types of cancer development while others are suspected risk factors for only a few cancer types.¹

For example, alcohol use is a definitive risk factor for several forms of cancer. When it comes to opioids and marijuana, however, research is limited and at times contradictory.^2-4 Nevertheless, the following content provides an overview of substances that are closely, loosely, or indirectly associated with an increased risk of cancer.

Alcohol and Cancer Risk

According to data from the National Cancer Institute, alcohol consumption is linked to several types of cancer, often in a dose-dependent manner. That is, the more a person drinks and the more regularly a person drinks over time, the higher the risk of developing some forms of alcohol-related cancer. Note, however, that not all cancer associations are dose dependent. That is, both binge drinkers and those who consume no more than one drink per day have a modestly increased risk for some cancers.²

Alcohol consumption has been linked to cancers including:^2,3,5

• Head, neck, and oral cancers. Alcohol can change the rate at which certain types of substances penetrate the mucosa within the mouth, which in turn may foster the development of cancer.⁵ Thus, higher risks of some head and neck cancers—including cancers of the oral cavity, throat, and larynx—are associated with moderate to heavy alcohol consumption.² Esophageal squamous cell carcinoma (which occurs inside the muscular tube connecting the throat to the stomach) is also associated with alcohol consumption as is an increased incidence of oropharyngeal cancer, which affects the back of the tongue, soft palate, tonsils, and side and back walls of the throat.^2,3
• Breast cancer. While alcohol consumption is sometimes linked to breast cancer in a dose-dependent fashion, even as few as 3 to 6 drinks per week can increase breast cancer risk.^2,3
• Liver cancer. Alcohol is a causative factor in liver cirrhosis, which can predispose people to cancer.³ So the link between liver cancer and alcohol is complex. That said, heavy alcohol consumption is associated with a roughly 2-fold increased risk of two particular types of liver cancer (i.e., intrahepatic cholangiocarcinoma and hepatocellular carcinoma).²
• Colorectal and prostate cancer. Up to a 1.5-fold increased risk of colon and rectum cancers are associated with moderate to heavy alcohol consumption.² However, even minimal consumption is linked to an increased risk of some prostrate and colorectal cancers.³

It’s important to note that the use of both alcohol and tobacco can have a compounding impact on cancer risk. Compared to the use of alcohol or tobacco, individuals who use both substances have a greater risk of developing cancers of the throat, oral cavity, larynx, and esophagus.²

Marijuana and Cancer

Carcinogens (i.e., substances that can increase cancer risk) are found in both tobacco and marijuana smoke, but marijuana contains 50% more carcinogenic hydrocarbons than tobacco.^6,7 Plus, a marijuana cigarette deposits 4 times as much tar in a smoker’s respiratory tract compared to a cigarette of the same weight.⁶

However, research has produced conflicting results on the cancer burden of marijuana, with one small study suggesting a link to laryngeal cancer, and an epidemiological survey-based study of 35 to 49-year-olds suggesting long-term use is associated with an increased risk of lung cancer.³

To further complicate matters, a recent systematic review and metanalysis of the research found insufficient evidence on the association between marijuana use and the development of lung cancer. The authors suggest that the heavy tar burden of marijuana joints vs. cigarettes appears to be counterbalanced by the usual practice of smoking fewer marijuana joints than tobacco cigarettes per day.⁸ The research review found a similar lack of sufficient evidence linking marijuana with nearly all other forms of cancer, with the exception of low-strength evidence that suggests that smoking marijuana is associated with the development of a specific type of testicular cancer.^8,9

Opioids and Cancer Risk

Opioids are an important drug class often used for cancer-related pain management.¹⁰ However, current data about opioids and cancer risk is contradictory, as it shows both positive and negative associations between cancer and opioids.⁴

For instance, some research shows that opioids such as fentanyl seem to inhibit cancer growth, metastasis, and proliferation.^4,10 Meanwhile, other studies suggest that some opioid receptors are linked to the increase and growth of cancer cells, enhanced formation of blood vessels, and metastasis (i.e., the development of secondary malignant growths).¹¹ Some data also suggests that opioids are linked to tumor development in the esophagus, stomach, and oral cavity.⁴

Researchers caution that data revealing potential cancer risks of opioids shouldn’t be interpreted as an argument against using opioids for pain management in cancer patients. Rather, nonopioid options should also be considered, and further research on the link between opioids and cancer risks need to be conducted.¹⁰

Cancer Risks Related to Cocaine, MDMA, and Inhalants

Does cocaine cause cancer? And what about inhalants and 3,4-methylenedioxy-methamphetamine (aka MDMA)? Are they among the list of substances that cause cancer?

The simple answer is: sort of. That is, sometimes it’s not the substances of abuse in and of themselves that increase cancer risk. Rather, the adulterants they’re mixed with and/or the chemicals that comprise their makeup may be carcinogenic. Some examples include:^12-15

• Benzene. Benzene—which is found in inhalants such as glues, adhesives, gasoline, paint strippers, cleaning products, and more—is associated with an increased risk of leukemia and other blood disorders.¹²
• Phenacetin. Data from the United Nations Office on Drugs and Crime reveals that various types of cocaine and cocaine derivatives are adulterated with phenacetin, a type of local anesthetic that’s also a suspected carcinogen. For example, U.N. testing revealed phenacetin was found in basuco (i.e., a form of Columbian cocaine), paco (a Latin American alternative), and crack in South America.¹³
• Safrole. According to an advisory from the Drug Enforcement Administration, safrole is sometimes used in the manufacture of MDMA (aka ecstasy and molly).¹⁴ Various animal studies suggest that safrole is a human carcinogen.¹⁵

Resources for Cancer and Substance Use

Myriad resources for cancer information and treatment are available. Two primary sources include:

• National Cancer Institute. Part of the National Institutes of Health (NIH), this government-funded organization is the principal agency for cancer research and training. Its website also offers a host of content regarding cancer-related topics, including diagnosis and staging, treatment, and cancer types.
• American Cancer Society. This national organization provides advocacy, research, and patient support. It offers educational content, links to research, and cancer-related programs and services.

Get Help for Addiction and Substance Misuse

For those facing cancer and substance misuse issues, it’s imperative to treat both conditions. Similar to cancer treatment, substance use disorder rehab is highly individualized. Multiple levels of care are available, including:¹⁶

• Detox.
• Inpatient rehab.
• Outpatient programs—including Intensive Outpatient Programs (IOPs), Partial Hospitalization Programs (PHPs), and telehealth care.

With facilities scattered across the country, American Addiction Centers offers the full spectrum of care, and rehab centers are in-network with myriad insurance providers, which typically cover part or all treatment costs.

Contact an AAC admissions navigator at to learn more about treatment and payment options, or fill out our insurance verification form to check insurance benefits. Treatment professionals can speak with you 24/7 to answer your confidential questions and help you take the first steps toward recovery today.