New IMRT techniques could be tissue-sparing and promote dosage conformity in breast cancer

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Published: 16 Dec 2014
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Prof Lorenzo Livi - Careggi Hospital, Florence, Italy

Prof Livi talks to ecancertv at SABCS 2014 about his work looking at new techniques in intensity modulated radiation therapy (IMRT) to improve dose conformity and reduce tissue damage in breast cancer.

 

 

The phase III study is a randomised clinical trial, randomised one to one, so one patient to the new technique, one patient to the standard technique. The new technique, IMRT, is a special technique to improve the dose conformity and the tissue sparing. Accelerated means each day more dose and less number of fractions.

So you’re highly targeting the dose but you also change the density of the dose?

Exactly, exactly in that way. Exactly.

So what exactly did you do in this regimen? Describe the protocol to me.

In the regimen the surgeon put the surgical clips on the tumour bed so you can identify on the CT, the planning CT, the clips. So the clips are the tumour bed and you draw with your hand a volume, it means clinical target volume, it is 1cm all around the surgical clips. After that another 1cm around the clinical target volume is called the planning target volume and you deliver the dose exactly in this volume, only in this small volume with respect to the whole breast.

And in a much shorter space of time.

Exactly, exactly.

So what happened in the study?

The study, to be honest, was excellent because nothing happened. So nothing new is good.

So are you saying that by carefully modulating the radiation to reach the lesion, the bed that was required, and changing the density it had no effect in comparison to whole breast?

Exactly. Not at first but I can see that it is better than the old technique because the cosmetic result was better, was significantly better. In terms of skin toxicity and also acute skin toxicity and early/late skin toxicity.

So the end point of this was toxicity, a quite important end point?

Yes, obviously. The secondary endpoint was toxicity; the first endpoint, the main endpoint, was local recurrences and at the moment with a median follow-up of five years we have the same local recurrences and it’s very important. Obviously we have to wait, we have to wait more time, maybe at least ten years, but just after five years the results are the same.

However acute and late toxicities are looking how?

Yes, exactly.

Is it looking good?

Yes, excellent. The worst toxicity was in the standard field, in the standard treatment. In the new technique it was excellent.

What then would you recommend doctors to be doing from now on with this data?

With this data I suggest, to be honest, waiting for another couple of years because the bigger American trial, B39, is near to be published. So I think with that study and our study we can obtain maybe the routine, the changed routine. But obviously B39 is bigger than our study because the study randomised, if I don’t make a mistake, around 3,000 patients and we only had 520 patients. So obviously the statistical power is different but the fact that we obtained a good result is just good news. So maybe in one year we can start to recommend for all of the patients that treatment.

So what message would you give to doctors for the time being, an interim message then, a practical message?

A practical message – at the moment follow the ASCO guidelines and in the next future waiting for the B39 and consider after that to use the technique that they consider better in their centre.

But you’re anticipating an improvement in toxicities?

Yes, exactly.