In most cases, you’ll take medicines for a long time. It may be for 5 to 10 years. The type of medicine depends on the type of cancer you’re trying to prevent.
Chemoprevention for breast cancer
The most common prevention medicines for breast cancer are called selective estrogen receptor modulators (SERMs). SERMs block the effects of estrogen, a female hormone, on breast tissue to help prevent breast cancer. Examples of SERMs are tamoxifen and raloxifene.
Aromatase inhibitors are another medicine that might help prevent breast cancer. They lower the amount of estrogen in the body. This can help prevent breast cancer, or stop it from coming back, in people who have gone through menopause. The U.S. Food and Drug Administration (FDA) hasn’t yet approved aromatase inhibitors for chemoprevention. But these medicines are approved to treat existing breast cancer.
Chemoprevention for colon cancer
Studies are being done to find out more about using chemoprevention to help prevent colon cancer. Some studies have found that nonsteroidal anti-inflammatory drugs (NSAIDs), like aspirin, can help prevent colon cancer.
NSAIDs can be an option for some people at high risk of getting colon cancer. For other people, the risks of taking NSAIDs long-term outweigh the benefits. Taking NSAIDs for a long time may cause serious side effects like bleeding, especially in older adults. That’s why experts don’t recommend NSAIDs for prevention for people who are not at high risk.
Chemoprevention for prostate cancer
Studies are being done on the effects of certain medicines, vitamins, and supplements on prostate cancer. They have looked at medicines called finasteride and dutasteride. But it's not known yet if they lower the risk of dying from prostate cancer. At the moment, there's no approved chemoprevention treatment for prostate cancer.