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Study: Extending aromatase inhibitor duration to 10 years lowers recurrence for ER/PR+ breast cancer patients

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Contents

At a glance In-depth
Findings     Limitations         
Clinical trials Guidelines                
Questions for your doctor             Resources                            


STUDY AT A GLANCE

This study is about:

Whether patients will benefit (lower risk of recurrence or new breast cancer in the other breast) if they stay on aromatase inhibitor therapy for 10 years rather than the standard 5 years.

Why is this study important?

According to the lead author of this research study, patients with breast cancer live for a long time, but “face an indefinite risk of relapse.”

Study findings: 

  1. When the study ended, 95% of women who had 10 years of aromatase inhibitor therapy (Letrozole) had disease-free survival (meaning they did not develop a recurrence or a new cancer in the other breast), while 91% of women who had 5 years of aromatase inhibitor therapy had disease-free survival at the study endpoint.
  2. Women who took the aromatase inhibitor for 10 years compared to 5 had no benefit in overall survival.

What does this mean for me?

This data suggests that extending aromatase inhibitor therapy to 10 years instead of stopping it at 5 may improve patient outcomes. Women who were on aromatase inhibitor therapy for 10 years did not have recurrences or develop new cancers in the other breast, although the difference between the 5-year and 10-year groups was relatively low. Women on 10 years of aromatase inhibitors experienced more side effects related to bone density and fractures. Women should have a risk/benefit conversation with their healthcare providers to discuss if extending aromatase inhibitor therapy is right for them. Patients also need to consider the side effects of aromatase inhibitors and the cost of the drug.

Posted 7/26/16

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References

Goss PE, Ingle JN, Pritchard K, et al, “Extending Letrozole for 5 years after completing an initial 5 years of Aromatase Inhibitor therapy alone or preceded by Tamoxifen in Postmenopausal Women with Breast Cancer: A Phase III Open Label Trial.” Presented by Paul Goss at the 2016 American Society of Clinical Oncology Meeting.  

Goss PE, Ingle JN, Pritchard K, et al, “Extending Aromatase-Inhibitor Therapy to 10 Years.” The New England Journal of Medicine. Published online first on June 5th, 2016.   

Goss, Pe. “Letrozole in the extended setting: MA.17.” Breast Cancer Research and Treatment. 2007;105:45-53.  

This article is relevant for:

This article is also relevant for:

Breast cancer survivors

ER/PR +

Women under 45

Women over 45

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IN DEPTH REVIEW OF RESEARCH

Study background:

Researchers of this current study explored whether extending the length of time women took the aromatase inhibitor provided additional benefit. Paul Goss and his colleagues at Massachusetts General Hospital and other institutions presented their data on this new clinical trial (MA.17R) at the 2016 American Society of Clinical Oncology Meeting, Their observations of what happens when women take an aromatase inhibitor for 10 years instead of 5 were also published in The New England Journal of Medicine.

This study follows previous research showing that taking an aromatase inhibitor (Letrozole) after 5 years of tamoxifen improved disease-free survival.

Researchers of this study wanted to know:

Whether patients who stay on an aromatase inhibitor for 10 years have fewer recurrences and develop fewer new breast cancers than patients who take aromatase inhibitors for 5 years.

Population(s) looked at in the study:

The study enrolled 1,918 postmenopausal women who had estrogen receptor (ER)- and/or progesterone receptor (PR)-positive, breast cancer.

Women in the study fell into 1 of 3 groups:

  • One group had received about 5 years of aromatase inhibitor (AI) therapy (Letrozole) in the researchers’ previous study, and took tamoxifen before AI therapy.
  • The second group of women was not included in the previous study, and had received any of the 3 aromatase inhibitors currently in use for about 5 years, and took tamoxifen before AI therapy.
  • The third group received about 5 years of any of the 3 current aromatase inhibitors currently in use, but never took tamoxifen.

Among the 3 groups of women, some were to receive another 5 years of AI therapy (Letrozole) or 5 years of receiving a .

Study findings: 

  1. When the study ended, 95% of women who had 10 years of aromatase inhibitor therapy (Letrozole) had disease-free survival (meaning they did not develop a recurrence or a new cancer in the other breast), while 91% of women who had 5 years of aromatase inhibitor therapy had disease-free survival at the study endpoint.
    • In total, 67 patients who took Letrozole for 10 years developed a recurrence of cancer in the other breast, compared to 98 patients who took Letrozole for 5 years.
  2. Women who took an aromatase inhibitor for 10 years had no additional benefit in overall survival compared to those who took an aromatase inhibitor for 5 years.
  3. Patients who took Letrozole for 10 years were more likely to develop bone fractures than the patients who took it only for 5 years (14% versus 9%).

Limitations:

This research did not take genetic status into account, so how women with mutations in or other genes that increase cancer risk respond to an additional 5 years of aromatase inhibitor therapy is unknown. Some patients involved in the study had previously taken tamoxifen, while some had not. From the data presented, it is not known if the use of tamoxifen before an aromotase inhibitor affected a patient’s risk of recurrence or new cancer. Finally, a number of aromatase inhibitors are available, and not all women in the study took the same aromatase inhibitor for the first 5 years.

Conclusions:

The results of this study suggest that taking an aromatase inhibitor for 10 years instead of 5 may benefit ER- and/or PR-positive breast cancer patients. But there was no increase in overall survival between women who took aromatase inhibitors for 5 years and those who took aromatase inhibitors for 10 years. Patients should discuss with their health care provider all the risks and benefits when thinking about extending their aromatase inhibitor for longer than 5 years.

Posted 7/26/16

Share your thoughts on this XRAYS article by taking our brief survey.

Expert Guidelines Expert Guidelines

In 2019, the American Society of Clinical Oncology (ASCO) published updated guidelines on endocrine treatment (hormonal therapy) for women with breast cancer. The guidelines recommended:

  • Women with node-positive breast cancer receive extended therapy, including an aromatase inhibitor, for up to a total of 10 years of endocrine treatment.
  • Many women with node-negative breast cancer should consider extended therapy for up to a total of 10 years of endocrine treatment based on considerations of recurrence risk.
  • The decision about extending hormone therapy should be a shared decision between doctors and patients based on discussions that weighs the benefits in lowering the risk for breast cancer recurrence, the benefits of prevention of second breast cancers versus the negative impact of side effects of treatment.

The Panel noted that the benefits in of reduction were small and that a substantial portion of the benefit for extended aromatase inhibitor therapy came from prevention of a new breast cancer diagnosis.

Updated: 01/02/2022

Questions to Ask Questions to Ask Your Doctor

  • Should I extend aromatase inhibitor therapy to 10 years?
  • What other ways can help me to prevent or lower my risk of breast cancer recurrence?
  • I have taken tamoxifen for 5 years; should I consider changing to an aromatase inhibitor?
  • What are the side effects and of hormonal therapies like tamoxifen?
  • What are the side effects and of aromatase inhibitors?
  • What are the added side effects of extending hormonal therapy beyond 5 years? 
  • I have been on an aromatase inhibitor and my bone density has gone down. Is there anything I can do to improve my bone density?

Open Clinical Trials Open Clinical Trials

The following are studies enrolling people with early ER-positive, breast cancer. 

A number of other clinical trials for patients with breast cancer can be found here.

Updated: 04/13/2022

Peer Support Peer Support

The following organizations offer peer support services for people with, or at high risk for breast cancer:

Updated: 02/25/2022

Who covered this study?

Clinical Oncology News

What Is the benefit of extending AIs beyond five years? This article rates 4.5 out of 5 stars

The Guardian

Breast cancer drugs should be given for 10 years, study shows This article rates 3.0 out of 5 stars

How we rated the media

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