Same Outcomes for Women Who Take Aromasin for 5 Years or Switch After Taking Tamoxifen

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Many postmenopausal women take hormonal therapy medicine -- either an aromatase inhibitor or tamoxifen -- after breast cancer surgery and other treatments for hormone-receptor-positive, early-stage breast cancer. Most women usually take hormonal therapy medicine for 5 years. Hormonal therapy can reduce the risk of the cancer coming back (recurrence). Hormonal therapy taken after surgery and other treatments is called adjuvant hormonal therapy.

A study found that women who took tamoxifen for 2.5 to 3 years and then switched to the aromatase inhibitor Aromasin (chemical name: exemestane) for 2 to 2.5 years (for a total of 5 years of hormonal therapy) had the same risk of recurrence as women who took Aromasin for 5 years. Other studies looking at other aromatase inhibitors also suggest that starting on tamoxifen and then switching to an aromatase inhibitor after 2 to 3 years is just as good as taking an aromatase inhibitor for 5 years. These results were reported at the 2009 San Antonio Breast Cancer Symposium.

This study, called the TEAM (Tamoxifen Exemestane Adjuvant Multinational) trial looked at 9,766 postmenopausal women diagnosed with hormone-receptor-positive, early-stage breast cancer. When the study started, the women were going to get either tamoxifen or Aromasin for 5 years. But other research suggested that Aromasin was more effective at preventing breast cancer recurrence, so 2.5 to 3 years after starting tamoxifen, those women were switched to Aromasin. The women who were taking Aromasin continued to take that medicine. All the women took hormonal therapy for 5 years.

Early results from the TEAM trial suggested that taking Aromasin for 5 years was better than starting on tamoxifen and switching to Aromasin. Still, as more information was collected the later results reported here showed no differences in outcomes for the two treatments.

Recurrence risk after 5 years was the same for both treatments:

  • 85.7% of the women who took Aromasin for 5 years were alive and didn't have a breast cancer recurrence
  • 85.4% of the women who took tamoxifen and then switched to Aromasin were alive and didn't have a breast cancer recurrence

Other benefits also were the same for the two treatments:

  • overall survival was the same
  • among women who had a recurrence, there was no difference in the length of time until the cancer came back

Other research has shown that an aromatase inhibitor is better than tamoxifen at reducing the risk of recurrence when the medicines are taken for 5 years, with no switching. Still, for a number of reasons, including side effects and cost, starting on tamoxifen and then switching to an aromatase inhibitor can be a good alternative to taking either tamoxifen or an aromatase inhibitor for 5 years.

Hot flashes and night sweats -- called vasomotor symptoms -- are side effects of both tamoxifen and the aromatase inhibitors, though they're more common with tamoxifen. Hot flashes and night sweats happen because these medicines reduce the amount of estrogen in the body. Joint pain is a more common side effect of the aromatase inhibitors. Doctors aren't sure why aromatase inhibitors can cause joint pain. Tamoxifen is available as a generic medicine, so tamoxifen can be much less expensive than an aromatase inhibitor (depending on insurance coverage).

If you're a postmenopausal woman diagnosed with hormone-receptor-positive, early-stage breast cancer, keep two things in mind when you and your doctor are deciding on a treatment plan:

  • 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.

Ask your doctor about the differences in benefits and side effects between aromatase inhibitors and tamoxifen. You may want to ask if taking the same hormonal therapy for 5 years or switching after 2 to 3 years on tamoxifen makes sense for you. If you're currently taking tamoxifen, ask whether switching to an aromatase inhibitor would be a good idea. Together, you can decide on a treatment plan that is best for YOU.

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