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Treatment Break From Extended Femara Doesn’t Affect Survival

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Survival rates were the same in postmenopausal women diagnosed with early-stage hormone-receptor-positive breast cancer whether they took a short treatment break during extended adjuvant hormonal therapy with Femara (chemical name: letrozole) or took Femara continuously for 5 years after previously taking hormonal therapy for an initial 5 years.

The research was published online on Aug. 10, 2021, by the journal Annals of Oncology. Read the abstract of Continuous vs intermittent extended adjuvant letrozole for breast cancer: Final results of randomized phase III SOLE (Study of Letrozole Extension) and SOLE Estrogen Substudy.”

Doctors call taking hormonal therapy for 10 years after surgery extended adjuvant hormonal therapy.

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 (chemical name: anastrozole)
  • Aromasin (chemical name: exemestane)
  • Femara

Doctors now prescribe these 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.

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.

In this study, the researchers wanted to see if women could take a short break from Femara each year during the second 5 years of hormonal therapy with no change in outcomes. They also wanted to see if a treatment break could ease side effects and improve quality of life.

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About the study

Called SOLE (Study of Letrozole Extension), this study analysis included 4,851 postmenopausal women diagnosed with early-stage hormone-receptor-positive, lymph-node-positive breast cancer.

After having surgery to remove the breast cancer, all the women took hormonal therapy for 4 to 6 years.

For the next 5 years of extended adjuvant hormonal therapy, the researchers randomly assigned the women to one of two treatment groups:

  • 2,426 women took Femara once a day for 5 years; this was called the continuous group
  • 2,425 women took Femara once a day for 9 months then stopped taking the medicine for 3 months during the first 4 years, and then took Femara once a day for the entire fifth year; this was called the intermittent group

Follow-up time was about 7 years.

The researchers wanted to see if disease-free survival rates were different between the two treatment groups. Disease-free survival is how long the women lived without a breast cancer recurrence.

Seven-year disease-free survival rates were:

  • 81.5% in the continuous group
  • 81.4% in the intermittent group

Side effects also were similar in both groups. An earlier analysis of the data found that women in the intermittent treatment group had better quality of life than women in the continuous treatment group.

“The similar disease-free survival coupled with previously reported quality-of-life advantages suggest intermittent extended treatment is a valid option for patients who require or prefer a treatment interruption,” the researchers wrote.

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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 likely will take some type of hormonal therapy medicine after surgery.

If your doctor recommends 5 more years of Femara after your first 5 years of hormonal therapy, you may want to bring up this study, especially if you start having troubling side effects.

For the first 4 years of extended Femara therapy, you may be able to take the medicine for 9 months and then take a 3-month treatment break. This may lessen any side effects you’re having without reducing the medicine’s benefits.

Together, you and your doctor 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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