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After 5 Years of Hormonal Therapy, 2 More Years of Arimidex Offers Same Benefits As 5 More Years for Postmenopausal Women With Early-Stage Breast Cancer

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After taking 5 years of hormonal therapy following surgery, postmenopausal women diagnosed with early-stage hormone-receptor-positive breast cancer got the same benefits from taking 2 more years of the aromatase inhibitor Arimidex (chemical name: anastrozole) as they did from taking 5 more years of Arimidex, according to a study.

The research was published in the July 29, 2021, issue of The New England Journal of Medicine. Read the abstract of “Duration of Adjuvant Aromatase-Inhibitor Therapy in Postmenopausal Breast Cancer.”

Doctors call treatments given after surgery adjuvant treatments.

About hormonal therapy
About the study
What this means for you

About hormonal therapy

After surgery, people diagnosed with early-stage hormone-receptor-positive breast cancer usually take hormonal therapy medicine to reduce the risk of the cancer coming back (recurrence).

Hormonal therapy medicines work in two ways:

  • by lowering the amount of estrogen in the body
  • by blocking the action of estrogen on breast cancer cells

There are several types of hormonal therapy medicines. Tamoxifen — a selective estrogen receptor modulator (SERM) — is one of the most well-known. Both premenopausal and postmenopausal women can take tamoxifen. In the early 2000s, the following aromatase inhibitors proved to be more effective at reducing recurrence risk in postmenopausal women:

  • Arimidex
  • Aromasin (chemical name: exemestane)
  • Femara (chemical name: letrozole)

Doctors now prescribe these three aromatase inhibitors more often than they prescribe tamoxifen for women who’ve gone through menopause. Aromatase inhibitors aren’t commonly used to reduce recurrence risk in premenopausal women.

For many years, women took hormonal therapy for 5 years after breast cancer surgery. Then research found that taking tamoxifen for 10 years instead of 5 years after surgery lowered a woman’s risk of recurrence and improved survival. Taking tamoxifen for 10 years after surgery became the standard of care in 2014.

In 2018, the American Society of Clinical Oncology (ASCO) updated its guidelines on adjuvant hormonal therapy, recommending postmenopausal women diagnosed with early-stage hormone-receptor-positive breast cancer that has spread to the lymph nodes (node-positive disease) receive hormonal therapy treatment, including an aromatase inhibitor, for 10 years after surgery. Doctors call taking hormonal therapy for 10 years after surgery extended adjuvant hormonal therapy.

Still, aromatase inhibitors can cause a number of troubling side effects, including hot flashes, joint pain, and bone pain. In some cases, the side effects are so bothersome that women stop taking the medicine early. Aromatase inhibitors also can cause osteoporosis, which increases the risk of breaking a bone.

The researchers who did this study wanted to see if taking 2 more years of Arimidex after 5 years of hormonal therapy offered the same benefits as taking 5 more years of Arimidex after 5 years of hormonal therapy. They also wanted to see if taking 2 more years of Arimidex rather than 5 years caused fewer or less severe side effects.

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About the study

Called SALSA (Secondary Adjuvant Long-Term Study with Arimidex), the study analysis included 3,208 postmenopausal women who had been diagnosed with stage I, stage II, or stage III breast cancer.

After having surgery to remove the cancer, all the women in the study had received 5 years of hormonal therapy:

  • 51% took tamoxifen
  • 7.3% took an aromatase inhibitor
  • 41.7% took tamoxifen and an aromatase inhibitor, one after the other

About 29% of the women in the study also had previously received chemotherapy treatment, and 80% had previously received radiation therapy.

The women in the study had an average age of about 64.

The researchers randomly assigned the women to one of two extended adjuvant hormonal therapy treatment groups:

  • 1,603 women took Arimidex for 2 more years
  • 1,605 women took Arimidex for 5 more years

The researchers followed half the women for more than 10 years and followed half for a shorter time.

Two years after the study started, 670 women (335 in each treatment group):

  • had recurrence
  • were diagnosed with a new primary breast cancer
  • died, though not necessarily as a result of breast cancer

Overall, disease-free survival rates were nearly identical in both treatment groups 10 years after the study started. Disease-free survival rates were:

  • 73.6% for women treated with 2 more years of Arimidex
  • 73.9% for women treated with 5 more years of Arimidex

Disease-free survival is how long a person lives with no cancer recurrence or second primary cancer diagnosis.

After 10 years, overall survival rates also were very similar for the two groups:

  • 87.5% for women treated with 2 more years of Arimidex
  • 87.3% for women treated with 5 more years of Arimidex

Overall survival is how long a person lives, whether or not the cancer comes back.

Five years after the study started, the risk of breaking a bone was lower in women treated with 2 more years of Arimidex than in women treated with 5 more years of Arimidex.

Fracture risk was:

  • 4.7% for women treated with 2 more years of Arimidex
  • 6.3% for women treated with 5 more years of Arimidex

Serious side effects also were more common in women taking 5 more years of Arimidex:

  • 26.5% of women treated with 2 more years of Arimidex had a serious side effect
  • 40.2% of women treated with 5 more years of Arimidex had a serious side effect

“[W]e found that a 5-year extension of adjuvant therapy with the aromatase-inhibitor anastrozole was not associated with a better outcome than a 2-year extension with respect to disease-free survival,” the researchers wrote. “Although disease-free survival and overall survival were similar in the two trial groups, the prolongation of anastrozole therapy led to additional side effects and resulted in more treatment-related clinical bone fractures.”

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What this means for you

If you’re a postmenopausal woman who’s been diagnosed with early-stage hormone-receptor-positive breast cancer, you will likely take some type of hormonal therapy medicine after surgery.

If your doctor recommends 5 more years of Arimidex after your first 5 years of hormonal therapy, it’s a good idea to bring up this study and discuss whether it may be possible to take 2 more years of an aromatase inhibitor instead of 5 more years. Together, you can decide on an extended adjuvant hormonal therapy treatment plan that’s right for you.

It’s also very important to talk to your doctor if you’re having troublesome side effects from your hormonal therapy medicine. There are ways to manage these side effects, including acupuncture, exercise, and medicine. You also may be able to switch to a different hormonal therapy.

Learn more about Hormonal Therapy.

To talk with others about your hormonal therapy experiences, join the Hormonal Therapy - Before, During, and After Discussion Board forum.

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Written by: Jamie DePolo, senior editor

Reviewed by: Brian Wojciechowski, M.D., medical adviser


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