Aromasin Slightly Better Than Tamoxifen at Reducing Recurrence Risk

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Aromatase inhibitors and tamoxifen are two types of hormonal therapy medicine given to postmenopausal women to lower the risk of hormone-receptor-positive, early-stage breast cancer coming back (recurrence). Hormonal therapy medicine given after surgery and other treatments (chemotherapy, radiation therapy) is called adjuvant hormonal therapy.

A study found that taking the aromatase inhibitor Aromasin (chemical name: exemestane) as adjuvant hormonal therapy lowers the risk of breast cancer coming back somewhat better than tamoxifen. These results were presented at the 2008 San Antonio Breast Cancer Symposium.

Postmenopausal women treated for early-stage, hormone-receptor-positive breast cancer commonly take hormonal therapy medicine for 5 years after surgery and other treatments. In some cases, women start taking tamoxifen and then switch to an aromatase inhibitor after a couple years. Some research suggests that taking hormonal therapy medicine for longer than 5 years might make sense for some women.

In this study, researchers found that women who took Aromasin as their first adjuvant hormonal therapy medicine were 17% less likely to have the cancer come back than women who took tamoxifen as their first adjuvant hormonal therapy medicine. Other research has shown that taking either of the other aromatase inhibitors: Armidex (chemical name: anastrozole) or Femara (chemical name: letrozole) as the first adjuvant hormonal therapy medicine also does a somewhat better job than tamoxifen at reducing the risk of breast cancer coming back. The benefits compared to tamoxifen is about the same for each of the three aromatase inhibitors.

Aromatase inhibitors help stop breast cancer from coming back by preventing the formation of estrogen. Tamoxifen works by blocking the effects of estrogen on breast cancer cells.

The study reviewed also is trying to figure out if starting on one type of adjuvant hormonal therapy medicine and then switching to another type after several years offers benefits. Other research has suggested that switching hormonal therapy types may make sense for some women.

Research continues to show that an aromatase inhibitor is the best hormonal therapy medicine to start with after initial breast cancer treatment for postmenopausal women diagnosed with early-stage, hormone-receptor-positive breast cancer. But tamoxifen is still a good choice, depending on your unique situation. For a number of reasons, including side effects and cost, tamoxifen may be a better choice for some women.

When you're deciding on a treatment plan, keep two things in mind:

  • Every woman responds differently to treatment. What works for someone else may not work for you and what works for you may not work for someone else.
  • Your treatment plan isn't written in stone. You can always switch medicines if another treatment has greater benefits and fewer side effects.

If you're a postmenopausal woman being treated for hormone-receptor-positive, early-stage breast cancer, talk to your doctor about the differences in benefits and side effects of aromatase inhibitors and tamoxifen. If you're currently taking tamoxifen, discuss whether switching to an aromatase inhibitor makes sense for you. Together, you can decide on a treatment plan that is best for YOU.

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