Adjuvant exemestane more effective than tamoxifen when combined with ovarian function suppression in young women with hormone-sensitive, early-stage breast cancer

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Published: 1 Jun 2014
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Dr Olivia Pagani - Oncology Institute of Southern Switzerland, Bellinzona, Switzerland

At a press conference at ASCO 2014, Dr Pagani presents a joint analysis of the IBCSG TEXT and SOFT trials - a randomised comparison of adjuvant aromatase inhibitor (AI) exemestane (E) plus ovarian function suppression (OFS) vs tamoxifen (T) plus OFS in premenopausal women with hormone receptor-positive (HR ) early breast cancer (BC).

Read the article or watch the interview for more.


 

Now you’ve been looking at what to do for young women, you had a median age of 43 years so that’s quite young, who have oestrogen receptor positive disease and you’re looking at an AI and ovarian function suppression. Tell me what you were trying to do in this study that you’ve just reported.

We were trying to show if aromatase inhibitors were as effective as in post-menopausal women compared to Tamoxifen which is standard treatment. To do that you have to give these premenopausal women ovarian suppression because aromatase inhibitors require low oestrogen levels which are, of course, usual in post-menopausal women. So to use these drugs you have to give ovarian suppression in premenopausal women to mimic a menopause.

And using ovarian suppression does have a history in Europe and perhaps less so in the USA.

It’s quite controversial, the impact of ovarian function suppression is still pending and we will be able to answer, hopefully, this question with the SOFT trial, the results will be presented later this year. But this trial was going to compare Tamoxifen and aromatase inhibitors and in practice changes in Europe we are more used to give ovarian function suppression, possibly because we use less chemotherapy in general, so we want to focus on the endocrine pathway.

So, in the setting of using ovarian function suppression you’ve combined the results of two trials, the TEXT and SOFT, and you’ve got nearly 5,000 patients in this. What did you do and what did you find?

We combined the results of these two trials which were originally planned to be analysed separately because, surprisingly, the outcome of these women was very, very good. So the outcomes when looking at the data separately would have been too long and too late. So we decided to combine these trials from the beginning and what we found is that exemestane plus ovarian function suppression is more effective than Tamoxifen plus ovarian suppression and improves all the disease outcomes, which is disease free survival, breast cancer recurrence free interval, distant recurrence free interval.

Now you have the overall survival is practically grazing 100% at five years, isn’t it? 95-96%. But the disease-free survival, there is a gap opening up, then, between the use of the aromatase inhibitor and Tamoxifen.

Yes, there is an improvement of 3.8% which is similar to what was seen with aromatase inhibitors in postmenopausal women compared to Tamoxifen. So we had the same results, comparable to what was seen with aromatase inhibitors in postmenopausal, which was what we were looking at.

But both Tamoxifen and the AI are good because you’ve got 91% versus 87%, so we’re talking about highly effective therapies here, aren’t we?

Yes. And what, in my opinion, is very important is that 43% of these women did not receive any chemotherapy. So this is a result with just combined endocrine therapy, which is amazing.

So you can offer a young woman a relatively non-toxic approach to resolving her disease?

Yes, you have to select these women quite carefully, of course, because the women who did not receive chemotherapy were at lower risk, they were a little bit older with tumours which were smaller, less node positive. But in this population 21% of the TEXT trial had node positive disease so it’s quite a brilliant result.

What are, then, the clinical implications that doctors could actually use, in your opinion, now?

In my opinion if you want to use the ovarian function suppression, so if you currently use ovarian function suppression now, the choice is to combine it with an aromatase inhibitor, in this case exemestane but we don’t think there is any difference between the different aromatase inhibitors.

You are going to get data on just how beneficial it is to use ovarian function suppression, aren’t you?

Yes.

That’s pending.

That’s still pending and so the results will be available at the end of this year.

So what’s your gut feeling about using this more complete form of hormone therapy?

I’m a believer of the ovarian function suppression because we think that this way we block the oestrogen pathway much more completely than using Tamoxifen alone, especially in very young women, younger than 40, for example, who are at higher risk, node positive for example, which is my clinical practice usually. So I will change my clinical practice now with these results.

So what’s the quick bottom line message for cancer doctors then?

It’s that you can have a very effective endocrine combination therapy with ovarian function suppression and an aromatase inhibitor. You can use this strategy in young pre-menopausal women and I think it’s very effective.