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


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Hormonal therapy reduces the risk of recurrence for women with early-stage breast cancer that is ER-and/or PR-positive. Standard therapy lasts 5 years. A new study looks at whether extending one type of hormonal therapy, known as aromatase inhibitor therapy, to 10 years lowers recurrence rates even more for these women. (7/26/16)

Contents

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


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 early-stage 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.

Expert Guidelines

In 2018, the American Society of Clinical Oncology (ASCO) published updated guidelines on endocrine treatment (hormonal therapy) for women with ER/PR-positive breast cancer. The guidelines recommended:

  • Women with node-positive breast cancer receive extended therapy, including an aromatase inhibitor (AI), for up to a total of 10 years of adjuvant endocrine treatment.
  • Many women with node-negative breast cancer should consider extended therapy for up to a total of 10 years of adjuvant endocrine treatment based on considerations of recurrence risk using established prognostic factors.

The guidelines also noted the following to inform the decision-making process:

  • For node-negative women with low risk for recurrence, oncologists should use an individualized approach to treatment duration based on a considerations of risk reduction and tolerability of additional treatment.
  • A substantial portion of the benefit for extended adjuvant AI therapy was derived from prevention of second breast cancers.
  • Shared decision making between clinicians and patients is appropriate for decisions about extended adjuvant endocrine treatment, including discussions about the absolute benefits in the reduction of breast cancer recurrence, the prevention of second breast cancers, and the impact of adverse effects of treatment.

Questions To Ask Your Health Care Provider

  • 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 toxicity of hormonal therapies like tamoxifen?
  • What are the side effects and toxicity 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

 

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, early-stage 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 randomized to receive another 5 years of AI therapy (Letrozole) or 5 years of receiving a placebo.

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 BRCA 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

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