Many studies presented at the 2005 ASCO Annual Meeting highlight new information on ways certain drugs can help people with cancer lower the risk of cancer or cancer recurrence (return of the cancer). According to the National Cancer Institute, more than 40 chemoprevention agents are being studied in cancer clinical trials. Chemoprevention drugs include the following categories:

Hormone therapy. These therapies block the body's production of hormones, such as estrogen. Some examples of hormone therapy include the following:

• Selective estrogen receptor modulators (SERMs), such as tamoxifen (Nolvadex) and raloxifene (Evista) for breast cancer
  
  
• Aromatase inhibitors, which slow or stop the growth of breast cancer by lowering the amount of estrogen in the body. These include anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin).
  
  
• Finasteride (Proscar, Propecia), which lowers levels of dihydrotestosterone (DHT) that contributes to the growth of prostate cancer

Nonsteroidal anti-inflammatory drugs (NSAIDs). These drugs are most often used to relieve pain and reduce fever, swelling, and redness. NSAIDs include aspirin, naproxen (Aleve), ibuprofen (Advil, Motrin, Nuprin), and ketoprofen (Actron, Orudis KT). Another group of NSAIDs is called cyclooxygenase-2 (COX-2) inhibitors, and works differently than aspirin to relieve pain and reduce swelling and redness. Some of these drugs include celecoxib (Celebrex), valdecoxib (Bextra), and rofecoxib (Vioxx). Many of these drugs are being studied in cancer prevention clinical trials, such as colorectal cancer prevention. However, recent studies have shown that people taking these drugs may be at increased risk for heart attack, stroke, and stomach bleeding, therefore the risks of these side effects must be weighed against the benefit of reducing the risk of cancer.

Statins. Preliminary studies suggest an association between statin use and a lower risk of colorectal cancer. However, controlled trials would be important to see if the association is real and if the relationship is cause and effect.

Vitamins. Using vitamins for chemoprevention has had mixed results. The combination of vitamin E and selenium to prevent prostate cancer is being studied in clinical trials.

The challenge of chemoprevention is to reduce a person's risk of cancer without causing unwanted or dangerous side effects. While some of the hormone therapies have been used to reduce the risk of cancer for many years, other types of chemoprevention are not as well studied, and the potential side effects are not known. People are encouraged to talk to their doctors before taking any drug or vitamin to prevent cancer.

Last Updated: December 19, 2007