ASTRO 2015

Accelerated partial breast irradiation valid alternative to whole breast irradiation in early breast cancer

Prof Vratislav Strnad - University Hospital Erlangen, Erlangen, Germany

Nowadays the typical situation is for breast cancer patients that the patients come to the therapy early and they have also early breast cancer. Early means a small tumour without lympho-metastasis, without distant metastasis and small means below 3cm, 2cm sometimes. Whatever the basic step, the fundamental first step of therapy is breast conserving surgery in a typical case, not mastectomy. But after breast conserving surgery the must second step is the radiation therapy. Until now the typical radiation therapy or the standard of radiation therapy is whole breast irradiation. Whole breast irradiation is time-consuming; you need at least six weeks for it, the minimum is three weeks but typically six weeks, and you do irradiation of the whole breast and the surrounding tissues. You irradiate also, together with the breast tissue, the skin, part of the lung, part of the heart and, of course, with such small tumours the question is is it really necessary, such extensive, such long-standing therapy and such a big exposure to the surrounding tissues? The solution may be, should be or can be also partial breast irradiation but until now we don’t have evidence, the so-called level  evidence, that the partial breast irradiation is really not inferior to the whole breast irradiation.

What was the aim and design of the study?

We started ten years ago a phase III trial with the goal to confirm or to dismiss the hypothesis that a partial breast irradiation using multi-catheter brachytherapy is the same or achieved the same results as the whole breast irradiation. We performed the study between 2004 up to 2009, recruiting altogether 1,200 patients. Now, after a follow up of nearly seven years we were able to present major five year results.

What were the main findings of the study?

Regarding the efficacy it means local recurrence rates, lymph node recurrence rates or so-called regional recurrence rates, distant metastasis rates, disease free survival, overall survival, we don’t have any differences between the results of whole breast and partial breast irradiation. More, if you look for the side effects we have by part of the side effects of radiation therapy no differences, by some, for example, skin side effects, skin based side effects or breast pain, a very low number of patients, 1%, 2%, 3%, 4%. It takes the breast pain after irradiation therapy but typically, particularly after external beam, here we have also a significant difference against whole breast irradiation as for partial breast irradiation. In other words, the efficacy of partial breast irradiation is the same as whole breast irradiation but is more gentle.

What are the potential advantages/disadvantages of the two approaches?

It’s really easy to describe. The first one, the disadvantage of full breast irradiation is time-consuming and significant radiation exposure to the skin, heart, particularly the heart, and the lung. The advantage is it is not an invasive technique. For partial breast irradiation using multi-catheter brachytherapy the advantage is a short therapy, only 4-5 days, it’s very, very gentle to the surrounding tissues, the radiation exposure to the organs, skin, heart and lung, is at least four times, five times, lower. The disadvantage is at the start of this treatment, this so-called minimally invasive procedure, a time of 15-20 minutes is necessary to insert these catheters inside the tissue on the breast, the risk tissue of the breast.

How are the results likely to affect practice, will they change the guidelines?

The results of this trial, it is the first trial regarding partial breast irradiation confirming the non-inferiority of partial breast irradiation. Of course it’s only confirmed for the multi-catheter brachytherapy. We believe that these results have potential to drive fundamental changes in the guidelines for therapy of early breast cancer because you have non-inferiority of partial breast using brachytherapy in comparison to the whole breast irradiation. Of course, tactically it’s possible to say we have two options, two equal options, but in radiation therapy we have also a rule, ALARA. ALARA means radiation dose, radiation exposure to the patient, should be ALARA – as low as reasonably achievable. In other words, we have by partial breast irradiation significantly lower doses to the whole body of patients, to the skin, to the heart, lung, whatever, and higher doses by whole breast irradiation. In other words, regarding efficacy these methods are equivalent but regarding safety, radiation safety, they are not.

What is your take home message?

The take home message is for our patients and for our physicians, oncologists, we have now for early breast cancer patients two alternatives of how to treat after breast conserving surgery, partial breast or whole breast. Everybody should know this data and decide the best therapy appropriate.