Read Original Story

Well done: STAT story on extended use of aromatase inhibitors for breast cancer


5 Star


Breast cancer treatment shows benefit to extended treatment with aromotase inhibitors

Our Review Summary

Woman looking at her ribbon before breast cancer awareness eventThis is a story about a new study on whether extending the use of letrozole (brand name Femara), a type of drug known as an aromatase inhibitor, reduces recurrence in breast cancer survivors.

Women who have undergone treatment for hormone-receptor positive breast cancer typically take aromatase inhibitors for the subsequent five years. The study showed that extending this treatment to 10 years lowers the rate of recurrence. The added benefit of continuing aromatase inhibitors for 10 years as opposed to five must, however, be weighed against the side effects. For women who are at high risk of recurrence, the results of this study are of particular interest.

The story does a commendable job of presenting a clear and balanced report of the study findings, and by stating that the results did not find a difference in overall survival.


Why This Matters

Continuing aromatase inhibitors beyond the standard five years is already a choice undertaken by some women and their doctors. This study is the first to rigorously address whether this is beneficial.


Does the story adequately discuss the costs of the intervention?


The story mentions costs. Letrozole, the aromatase inhibitor used in the trial, is available as a generic for less than $100 a month.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?


The benefit of continuing aromatase inhibitors for five additional years is presented clearly. The study shows that among hormone-receptor positive breast cancer survivors, the risk of recurrence is lower for women continuing aromatase compared to those who did not, particularly in the opposite breast. The story breaks down the figures by whether recurrence occurred in the original breast or in the opposite breast:

In a randomized controlled trial, 959 women were given the drug and 959 a placebo. Thirteen of the women taking the drug for an additional five years developed breast cancer in the opposite breast during the study, compared with 31 taking the placebo; 55 and 68, respectively, developed a recurrence of cancer in the original breast.

Later in the story, the overall recurrence rate is given.

95 percent of those taking letrozole for the additional five years remained free of breast cancer (meaning the disease had not returned in the original breast or developed in the opposite one). Of those taking an inert pill, or placebo, 91 percent did.

The story could have gone a step further by explaining more clearly what the recurrence rate for breast cancer is normally. The description of “200 to 1 odds per year” is not easy to understand and it’s unclear if the recurrence rate in the study was lower than expected in the general population.

Does the story adequately explain/quantify the harms of the intervention?


First, we applaud the story for recognizing the difference between absolute and relative benefits.

But because the absolute benefits were not huge, and because the drug did cause side effects, it makes sense to consider this for women at the highest risk of a recurrence of breast cancer, he said.

The story also clearly understands that the absolute benefit of the treatment must be weighed against the side effects:

Aromatase inhibitors cause side effects in some women, especially night sweats, hot flashes, and sexual dysfunction. Women receiving five more years of letrozole also had greater loss of bone in their hip, worse osteoporosis, and more fractures.

One thing that would have made this even stronger: Including the rates of the different side effects.

Does the story seem to grasp the quality of the evidence?


The type of conclusions drawn by the story are supported by the design study being a randomized controlled trial. A strong grasp of the quality of the evidence is exhibited by recognizing these important caveats:

The study did not continue long enough to discover whether the lower risk of developing cancer in the opposite breast translated into a lower risk of death.

There was no difference in survival, however: 100 women in each group died during the study.

Dr. J. Leonard Lichtenfeld, deputy chief medical officer for the American Cancer Society cautioned, however, that “one has to be cautious in interpreting these results,” partly because “based on what they show, there is no overall change in survival.”

Does the story commit disease-mongering?


There is no disease mongering in terms of the overall risk of developing breast cancer or the risk of recurrence.

Does the story use independent sources and identify conflicts of interest?


Kudos here, too. Dr. Richard Schilsky was interviewed as an independent source. Conflicts of interest were also disclosed: The study was funded by Novartis which sells letrozole, and several of the study authors are connected to pharmaceutical companies.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

Continuing aromatase inhibitor was compared to not continuing it. There was a brief mention that study participants had taken another drug, tamoxifen, before starting letrozole. However, we’d have liked to have seen details on what other long-term alternatives women have for preventing recurrence.

Does the story establish the availability of the treatment/test/product/procedure?


The drug letrozole is already available, and the story makes this clear.

Does the story establish the true novelty of the approach?


The story adequately establishes the novelty of the study:

“The reason this is a milestone trial is that it’s the first to show that 10 years [on letrozole] is better than five,” said Dr. Nicholas Robert, an oncologist with Virginia Cancer Specialists and a co-author of the study.

“…If you can tolerate the side effects, I think many women will opt to take the extra years of letrozole, so this study is practice-changing.”

This is important because many patients already continue aromatase inhibitors:

Experts said the study was significant because some women and their doctors choose to continue aromatase inhibitors past the standard five years. There had been no research on whether that was beneficial.

Does the story appear to rely solely or largely on a news release?


The story had interviews with independent sources and does not appear to be copied from a news release.

Total Score: 9 of 10 Satisfactory

Comments (2)

Please note, comments are no longer published through this website. All previously made comments are still archived and available for viewing through select posts.

Marc Beishon

June 10, 2016 at 10:54 am

I’m not sure this warrants such a high rating as it doesn’t address why the experts see it as significant if there is no survival benefit. Is an absolute difference of 4% – and less if you just take recurrence in the same breast – practice changing, given the challenges of compliance in taking drug with side effects for many for ten years?

And critically there is a qualification made by one: “it makes sense to consider this for women at the highest risk of a recurrence of breast cancer” – so who is at high risk and how do we know?


Jean Anne Booth

June 13, 2016 at 7:06 am

As a breast cancer survivor, and having recently had to make my own decision about whether or not to continue aromatase inhibitors past my initial 5.5 years, I found this article to be quite excellent. Today’s standard of care is simply a mention that “Some recommend continuing aromatase inhibitors for an additional 5 years”, depending on your tolerance of it – but with no data on it, just a reference to the similar study on tamoxifen. (And tamoxifen is a completely different drug, so who knows if the impact is the same?) Cancer survivors who did a genetic assay of their tumor – as I did – know their risk of recurrence very well. Since my risk is 15%, I chose not to continue aromatase inhibitors, as the side effects have significantly impacted my quality of life. After reading this article, I’m even more comfortable with the choice I made.