What Are the Best Aromatase Inhibitors?

Aromatase inhibitors stop estrogen production in postmenopausal women. This is useful in women who have a type of breast cancer that responds to estrogen hormones. All three aromatase inhibitors are equally effective and have similar side effects, but some patients may tolerate one drug better than another.

Aromatase inhibitors are a type of hormone therapy that stops the production of estrogen in postmenopausal women. They work by blocking the enzyme aromatase, which converts other hormones such as androgens into estrogen in the body. This reduces the amount of estrogen available, which slows or stops the growth of hormone-receptor-positive breast cancer cells.

Aromatase inhibitors are used to treat hormone receptor-positive early, locally advanced, and metastatic breast cancers.

Women who have hormone receptor-positive breast cancer may be prescribed an aromatase inhibitor (alone or after several years of tamoxifen) to lower the risk of:

• Breast cancer recurrence
• Breast cancer in the opposite breast
• Death from breast cancer

There are three aromatase inhibitors currently available. All are taken orally, in pill form, and are available as generics. 

• Anastrozole (Arimidex)
• Exemestane (Aromasin)
• Letrozole (Femara)

Side effects of aromatase inhibitors include: 

• Muscle pain
• Joint pain or stiffness
• Menopausal symptoms (such as hot flashes, night sweats, and vaginal dryness)
• Loss of bone density (osteoporosis)/broken bones
• Increased risk of heart problems compared to tamoxifen
• Increased cholesterol

All three aromatase inhibitors are equally effective and have similar side effects, but some patients may tolerate one drug better than another.