COMMENTARY

ARTISTIC: Sparing Radiotherapy After Prostate Cancer Surgery? 

Claire Vale PhD

Disclosures

September 28, 2019

This transcript has been edited for clarity.

I'm Claire Vale. I'm a research scientist based at the MRC clinical trials unit at UCL in London. And principally, I run systematic reviews and meta-analyses.

Describe the research you presented at ESMO

I've just presented the first results from a prospective meta-analysis, comparing the use of adjuvant radiotherapy with early salvage radiotherapy, in men with localised prostate cancer, at high risk of relapse.

What were the results?

At the moment, we only have results for our first outcome, which is event-free survival, and event-free survival is dominated by biochemical recurrence in these men. And what we see is very consistent results from the three trials. And when we put them together in a meta-analysis, we saw an overall hazard ratio of 1.12, and that's a 12% relative improvement in event-free survival with early salvage radiotherapy. Although that result isn't statistically significant, our best estimate is of a 1% difference between the two treatments at 5 years.

How did you go about the study?

We've been working on ARTISTIC as we've called it for quite a long time. And first of all, it came about with discussions with some of the individual trial teams. And back in 2014, we set up a collaboration. It was myself and colleagues from the Medical Research Council clinical trials unit, along with the investigators from the three trials – RADICALS-RT, the GETUG-AFU17 study and the Trans Tasman Radiation Oncology Group RAVES trial. And each of those three trials essentially set out to ask the same question of this treatment comparison between whether adjuvant or early salvage radiotherapy was preferable in these men.

But I think quite quickly, for a number of reasons, they realised that they weren't going to get reliable results from their trials. And so we started working together collaboratively to plan a meta-analysis at the earliest possible time point. We've presented today on the same day that RADICALS-RT presented its first results. And just a couple of weeks after one of the other studies, RAVES, presented its results at a separate meeting.

What are the clinical implications?

I think there's been ongoing uncertainty in the community about whether adjuvant or early salvage policies for radiotherapy were the way to go in terms of treating these men who had localised disease but were at a high risk of relapse.

I think what the results we've seen today have shown is that actually early salvage is certainly no worse than adjuvant radiotherapy, and there are some indications that it may be better - largely, I think better, not in terms of the actual outcome, it's very tiny differences between the studies and we can't show those reliably at the moment because the differences are so small.

But actually the advantage of the early salvage regimen is that it spares many men from having to undergo radiotherapy unnecessarily perhaps.

What are your next steps?

We're just pulling together updated results from the third study in particular. Whereas RADICALS and RAVES have presented their first results, GETUG-AFU17 are yet to present any results. So we've been lucky that they've shared with us interim data. They're in the process of updating their own trial data. And we look forward to having that very soon actually, to include it in an updated meta-analysis.

The immediate step is to update our analysis that we've presented today. We don't anticipate it's going to change very much. But the updated French results should strengthen the analysis we've seen today.

And we plan to look at patient subgroups. So: whether there's a difference in the effect of these two treatments in any particular groups of men. So perhaps men at the highest risk of relapse or with the most significant high-risk features.

Are you encouraged by the data so far?

It's always tricky, isn't it? Because it's not a positive result as such. The trials and the meta-analysis set out to test whether adjuvant radiotherapy improved outcomes for these men compared to the early salvage policy. And we haven't shown that, but I think the encouraging thing to take from those results is the fact that actually, we can reduce unnecessary treatment, or potentially over-treatment of these men, and that's got to be good news, because radiotherapy, all cancer treatments essentially, come with side effects for these men.

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