If you have a higher risk of developing cancer or of cancer coming back, there may be medication available to help lower that risk. This is called "chemoprevention."
Cancer begins when healthy cells change and grow out of control. The process of a healthy cell becoming cancerous often takes years. Many genetic and lifestyle factors, such as smoking, may affect this process. Cancer chemoprevention uses drugs, vitamins, and other substances to help keep cancer from developing or keep cancer from coming back.
There are many reasons why a person might have a higher risk of developing cancer. These include:
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A personal history of cancer, which puts you at risk for the cancer coming back (called a recurrence) or a second cancer developing
Although it is not possible to always prevent cancer from happening, chemoprevention can lower a person's chance, or risk, of getting cancer.
Researchers are always trying to find new ways to prevent and reduce the risk of cancer. This article is about the different types of chemoprevention that are available for specific types of cancer. Talk to their doctor about your personal risk of cancer and discuss the ways to reduce the chance that cancer will develop. Learn more about understanding cancer risk.
What are the risks and benefits of chemoprevention?
The risks and benefits of chemoprevention are different for each person and depend on the drug being taken. When considering taking a drug for chemoprevention, it is important to think about the following:
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Like other medications, drugs that may lower the risk of cancer can also cause side effects. People with a higher risk of developing cancer may be willing to accept some side effects. But others may not want to use a drug that gives them side effects when they are not sick. This is a personal decision.
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The risk-reduction effect of chemoprevention seen in research studies may be different from what you experience.
Ask your doctor about the potential risks and potential benefits of chemoprevention for you.
Below is general information about chemoprevention for three common types of cancer: breast cancer, colorectal cancer, and prostate cancer. There is also information about clinical trials exploring chemoprevention for other types of cancer.
What drugs are used to help prevent breast cancer?
Some breast cancer tumors need hormones to grow. This type of breast cancer is called hormone-receptor positive (HR+) breast cancer. Medication that blocks these hormones can help prevent this type of breast cancer from developing.
Tamoxifen (available as a generic drug). Tamoxifen is a type of drug called a selective estrogen receptor modulator (SERM). It blocks the effects of estrogen on tumor growth and is used to treat breast cancer. It can also be used to reduce the risk of developing breast cancer for people who are at a high risk of developing the disease.
Tamoxifen may be an option for women who are age 35 and older who have a high risk of developing breast cancer. It can also help if you have been diagnosed with:
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Non-invasive breast cancer, also called ductal carcinoma in situ (DCIS)
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Precancerous breast conditions called lobular carcinoma in situ (LCIS) or atypical hyperplasia of the breast
Tamoxifen is not recommended during pregnancy, if you are trying to become pregnant, or during breast feeding. It is also not recommended for people with a history of blood clots or strokes, or who are immobilized (unable to move around) for a long time.
Raloxifene (available as a generic drug). Raloxifene is also a SERM. It may be an option after the age of 35 when there is a higher risk of breast cancer and after menopause. It is also used to prevent bone loss from osteoporosis. Raloxifene is not recommended for people with a history of blood clots or strokes, or who are immobilized for a long time.
Aromatase inhibitors (AIs). This category of drug reduces estrogen by blocking estrogen production. Aromatase inhibitors can be used to prevent a breast cancer recurrence after menopause. There are three aromatase inhibitors that can be used as chemoprevention for breast cancer:
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Anastrozole (Arimidex)
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Exemestane (Aromasin)
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Letrozole (Femara)
Aromatase inhibitors are not usually recommended for people who have a history of osteoporosis.
Learn more about breast cancer risk factors and prevention.
What drugs are used to help prevent colorectal cancer?
Some research has suggested that aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce the development of polyps in people who have a history of colorectal cancer or polyps. However, regular use of aspirin or NSAIDs has serious side effects, including bleeding of the stomach lining as well as blood clots that can lead to stroke or heart attack. People should talk with their doctor about the risks and benefits of taking aspirin on a regular basis.
Learn more about colorectal cancer risk factors and prevention.
What drugs are used to help prevent prostate cancer?
The drugs dutasteride (Avodart) and finasteride (Proscar) are used to treat a condition called benign prostatic hypertrophy (BPH). These drugs are in a category called 5-alpha-reductase inhibitors (5-ARIs). They may also lower the risk of developing prostate cancer. However, long-term research of these drugs is currently ongoing and they are not currently approved for the prevention of prostate cancer.
The decision to take a 5-ARI is different for each person. Anyone considering taking this class of medication should talk about the possible benefits and possible side effects with their doctor.
Learn more about prostate cancer risk factors and prevention.
What kinds of chemoprevention are currently being studied in cancer clinical trials?
Clinical trials are research studies involving volunteers. Researchers use clinical trials to find out if chemoprevention substances are safe and effective in delaying or preventing certain types of cancer. Many types of chemoprevention have been studied in clinical trials, and research in this area is ongoing. For example, researchers are testing different ways of using medication to prevent esophageal cancer, stomach cancer, laryngeal and hypopharyngeal cancer, oral and oropharyngeal cancer, and more.
Sometimes, clinical trials have shown that some medication can cause harm instead of help prevent cancer. For example:
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Beta carotene, a substance found in carrots, squash, and similar vegetables, was once thought to help prevent lung cancer. But clinical trials showed that taking a beta carotene supplement raised the risk of lung cancer in people who smoked.
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A clinical trial of selenium and vitamin E supplements for prostate cancer showed that neither lowered the risk of the disease. And there was evidence that people who took vitamin E had a higher risk of prostate cancer. Learn more about vitamins and minerals and cancer prevention.
Clinical trials also show that some substances used for chemoprevention do not work for everyone. When looking at the results of chemoprevention clinical trials, make sure to ask about the group of participants. Often, people participating in these types of clinical trials have known, increased risks for cancer. These may include smoking or having a family history of cancer. This means the results of the study may not apply to everyone.
Always talk with your doctor before taking any medications or dietary supplements, even if it is one you have taken in the past. Some dietary supplements, including herbal products, can interfere with other medications you are taking. Supplements can cause unwanted side effects or even reduce a medication's effectiveness.
Your health care team can also help you understand any research you read about chemoprevention. Learn more about understanding cancer research. Your doctor can also talk with you about your specific risk for different cancers and other potential ways to reduce cancer risk.
Questions to ask the health care team
Consider asking your health care team the following questions about chemoprevention:
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What is my risk of developing cancer?
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How does my current health affect my risk of developing cancer?
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Are there any chemoprevention medications I can take to reduce my risk of developing cancer?
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How much will this chemoprevention lower my cancer risk? For which types of cancer?
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What side effects could I experience if I take this medication?
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What are the risks and benefits of chemoprevention for me?
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Is a chemoprevention clinical trial an option for me?