Radiation therapy for breast cancer can be safely shortened by changing technique

Dr Sofia Rivera - Institut Gustave Roussy, Villejuif, France

I had the pleasure to present in the Presidential session the results of the HypoG-01 trial which is a randomised phase III trial assessing moderately hypofractionated radiotherapy for nodal irradiation in breast cancer. So up to HypoG we had quite a number of trials showing that hypofractionated radiotherapy was doable and non-inferior for breast only radiotherapy but we had no previous trials with modern radiotherapy assessing the hypofractionated radiotherapy, so shorter regimens, when irradiating not only the breast but also the lymph nodes around. So for a little bit more advanced disease.

With this trial we have demonstrated the non-inferiority of a three-week regimen, so a hypofractionated regimen, compared to the still standard in most countries five weeks’ radiotherapy when irradiating the nodes. We have demonstrated that on the primary endpoint which was based on toxicity, so the cumulative incidence of arm lymphedema. Numerically we have shown that we have no obvious difference between moderately hypofractionated radiotherapy and normal fractionated radiotherapy, no matter which type of toxicity we look at – cardiac toxicity, lung toxicity, local toxicity on the skin, also fatigue. Everything was pretty similar.

Regarding survival, we also have very interesting data in terms of overall survival, cancer specific survival, disease free survival. Because we saw, for instance, an overall survival hazard ratio of 0.59. So with that it makes a big change in practice because now we don’t need any more long radiotherapy over five weeks, just three weeks will be enough. Not only as it was shown by, in the past, for breast alone but also for patients with a little bit more advanced disease requiring nodal irradiation.

What are the next steps?

We will have the follow-up up to ten years of the patients, of course. Of course regarding cardiac toxicity, we will also analyse the dose distribution of radiotherapy to follow up on the long-term run.

What are your hopes for the long-term clinical impact of this study?

We really think that this will change the practice in most countries. There is another trial running, now ended, which is the Skagen-1 trial and we hope to publish back-to-back the results. So having two randomised phase III that we hope will be showing the same thing will really consolidate these results and make no doubt about the fact that no matter the ethnic origin, no matter the size, the weight of the patient, this would be applicable for all patients.

Anything you would like to add?

Maybe just to mention that the HypoG-01 trial is a fully academic funded trial and so that’s really nice to see that even with academic funding you can reach a change in practice.