BACKGROUND: Aromatase inhibitors (AIs) are a relatively new class of drugs for women with breast cancer. While AIs have been around for years, the data from the longer studies is now becoming available. These studies are showing how AIs may play an important role in the treatment and prevention of a recurrence of breast cancer. AIs help to prevent the growth of tumors that are estrogen sensitive by lowering the amount of estrogen in the body. Tamoxifen is the treatment of choice and gold standard for hormone therapy for breast cancer patients. Both tamoxifen and AIs help reduce the growth of the estrogen-sensitive breast tumors, but they work differently. AIs reduce the amount of estrogen in the body, while tamoxifen blocks a tumor’s ability to use estrogen. There are three AIs approved by the FDA including anastrozole (Arimidex), exemestane (Aromasin) and letrozole (Femara).

THE RESEARCH: Research shows tamoxifen therapy stops working after five years, yet one-third of cancers come back five to 10 years later. But that may be where AIs may play a major role. A study published in 2004 in The New England Journal of Medicine shows taking Aromasin after two to three years of tamoxifen reduces breast cancer recurrence by 32 percent. Another study shows women can cut their risk of recurrence by nearly half by taking Femara after they completed five years of tamoxifen. And a third study shows post-menopausal women who switched to Arimidex after two or three years of tamoxifen had fewer recurrences of cancer than those who continued to take tamoxifen for the full five years. There are many more studies showing the benefits of AIs in preventing recurrence of breast cancer.

SIDE EFFECTS: Another benefit of AIs is patients tend to have fewer side effects. The risks with tamoxifen include endometrial problems and blood clots, but these risks have not been seen with AIs. However, AIs do cause bone loss, so women on these drugs need to take extra steps to prevent osteoporosis or bone fractures. AIs are also only a treatment choice for postmenopausal women. Because they act only on estrogen that’s produced outside the ovaries, AIs are only effective in post-menopausal women. Before menopause, most of the body’s estrogen is produced in the ovaries. However, doctors are looking at putting a woman with breast cancer into menopause in order to give her more treatment options.

WHAT SHOULD PATIENTS DO? While researchers are optimistic that AIs help prevent recurrence of breast cancer, it is still not clear what the best strategy is to do this. But experts say patients need to talk to their oncologist about the emerging data to help them determine their options.

For More Information, Contact:
Imez Sims
Clinical Research Coordinator
Moffitt Cancer Center
12902 Magnolia Dr. MBC-PR
Tampa, FL 33612
(813) 745-1656