The short answer
Anabolic-androgenic steroids, sometimes misused for muscle building, are classified as probably carcinogenic, with a suspected link to liver cancer and tumors. Avoiding non-medical use reduces risk.
Anabolic steroids is classified as a probable human carcinogen (IARC Group 2A).
People are mainly exposed by non-medical use for muscle building, often at high doses.
It is most strongly linked to a suspected link to liver cancer and tumors.
A carcinogen classification describes hazard — whether something can cause cancer — not your personal risk at a given exposure.
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The full explanation.
The simple version
Anabolic steroids are lab-made versions of testosterone. Some people misuse them to build muscle. Beyond many other health harms, they are classified as a probable carcinogen, with a suspected link to liver tumors and cancer.
What anabolic steroids is
Anabolic-androgenic steroids are synthetic hormones related to testosterone. They have legitimate medical uses but are also misused, often at high doses, for athletic or cosmetic muscle building. IARC classifies them as probably carcinogenic to humans.
How people are exposed
Common ways people come into contact with it:
- Non-medical use for muscle building or athletic performance
- High-dose or long-term misuse
- Legitimate use is medically supervised
The cancer connection
Anabolic steroids are linked, with limited evidence, to liver cancer and benign liver tumors that can bleed or turn malignant.
The International Agency for Research on Cancer (IARC), the cancer arm of the World Health Organization, places anabolic steroids in Group 2A, probably carcinogenic to humans — meaning the evidence in people is limited but there is strong support from animal or mechanistic studies.
Hazard is not the same as risk
It helps to separate two ideas that are easy to mix up: hazard and risk. When an agency lists anabolic steroids as a carcinogen, it is making a statement about hazard — whether the substance is capable of causing cancer under some conditions. It is not, by itself, a statement about your personal risk, which depends on how much you are exposed to, for how long, and other factors. Two substances in the same group can carry very different real-world risks. The label answers "can it cause cancer?" — not "how likely is it to cause cancer for me?"
How to lower your exposure
- Avoid non-medical steroid use
- Use prescribed hormone treatments only under medical supervision
- Seek help if you are using steroids and want to stop safely
If you are looking at your overall cancer risk, small, steady steps add up. See our overview of cancer prevention and what raises cancer risk to put any single exposure in context.
The bottom line
Anabolic steroids is a probable human carcinogen (IARC Group 2A). The most important thing you can do is understand where exposure comes from and take reasonable steps to reduce it, without losing sleep over a single label. Focus your energy on the biggest, most controllable risks in your own life.
Words to know
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Common questions
▸Does anabolic steroids cause cancer?
Probably. Anabolic steroids is classified as a probable human carcinogen: the evidence in people is limited, but animal and laboratory studies support a link. "Probable" means suspected on solid grounds, not proven.
▸How are people exposed to anabolic steroids?
Most exposure happens by non-medical use for muscle building, often at high doses.
▸Which cancers are linked to anabolic steroids?
It is most strongly linked to a suspected link to liver cancer and tumors.
▸How can I reduce my exposure to anabolic steroids?
The main steps are avoiding non-medical steroid use.
▸Does a carcinogen label mean I will get cancer?
No. A classification is about hazard — whether anabolic steroids can cause cancer under some conditions — not a prediction that any one exposed person will develop cancer. Your actual risk depends on the amount and length of exposure and other factors.
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