What is Chemoprevention?

Author: OncoLink Team
Content Contributor: Allyson Distel, MPH
Last Reviewed: March 01, 2024

Chemoprevention is the use of a medication, vitamin, or supplement to stop cancer from happening. This is most often used for people who have a high risk of cancer. They may have a strong family history, carry a certain gene, or have a personal health history that makes their risk higher.

It can be used in three ways:

  • Primary prevention: Prevent cancer in a healthy person.
  • Secondary prevention: Prevent a pre-cancerous area from becoming cancer.
  • Tertiary prevention: Used for a person who has already had cancer, to prevent them from developing another cancer.

What makes a good chemoprevention agent?

  • Does not cause side effects that affect the quality of life or are dangerous.
  • Does not cost a lot of money and is easy to get.
  • Can prevent cancer.

What are some examples of chemoprevention?

Chemoprevention in Breast Cancer

Breast cancer chemoprevention trials have set the standard for other cancer types to follow. Tamoxifen and Raloxifene are medications (also called SERMs). SERMs work to prevent breast cancer by interfering with estrogen, a female hormone that causes breast cancer growth. Both medications have been found to reduce breast cancer risk.

Chemoprevention in Prostate Cancer

Prostate cancer is the most common cancer that occurs in men. Many studies have looked at medications (finasteride and dutasteride), vitamins, and supplements (vitamin E, selenium, beta-carotene) to prevent prostate cancer. The studies of finasteride and dutasteride found that their risks outweighed the benefits. Studies have found that the risk of prostate cancer was not reduced when taking selenium or beta-carotene. There were higher rates of prostate cancer when high-dose vitamin E was taken. Due to these studies, chemoprevention is not used to prevent prostate cancer. But, researchers continue to look for a substance that will help reduce risk.

Chemoprevention in Colon Cancer

Studies have found that regular use of aspirin and/or other non-steroidal anti-inflammatory drugs (NSAIDs) results in a 20-40% reduction in the risk of developing colorectal polyps and cancer. This sounds like great news, but there are a few things to think about. These medications need to be taken regularly, for a long period (10 or more years). NSAIDs and aspirin have side effects such as bleeding and can cause an increased risk of heart disease. These medications may be most useful in people with a high risk of colon cancer, including those with a genetic risk. Talk to your healthcare provider before starting any medication.

Other Cancer Types

Chemoprevention is also being studied in other cancers such as head and neck, lung, and skin cancer. Only large clinical trials that are done for many years can show if a compound will reduce the risk of cancer.

Is chemoprevention right for you?

Every medication, vitamin, or supplement can have side effects. In some cases, these can be serious. Talk about the risks of any chemoprevention with your healthcare provider. In some cases, there are more risks than benefits, and you may decide chemoprevention is not right for you. In other people, the benefit of cancer prevention may make the side effects tolerable. It is your choice, and you need to think about your personal cancer risk and health history.

Cancer.net (2019). Chemoprevention.

Fisher B, Jeong JH, Dignam J, et al. Findings from recent National Surgical Adjuvant Breast and Bowel Project adjuvant studies in stage I breast cancer. J Natl Cancer Inst Monogr 2001;30:62–66.

Lippman SA, Klein EA, Goodman PJ, et al. Effect of Selenium and Vitamin E on Risk of Prostate Cancer and Other Cancers. JAMA. 2009;301(1):39-51.

National Cancer Institute (2023). Breast Cancer Prevention.

National Cancer Institute (2023). Prostate Cancer Prevention.

The STAR Trial Questions & Answers.

Up to Date – Chemoprevention strategies in prostate cancer.

Up to Date – NSAIDS: Role in prevention of colorectal cancer.

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