A type of radiotherapy that shapes radiation beams to tumors has grabbed headlines today. But more in-depth trials, already underway, are needed to give a clearer picture of the benefit for men.

26 Sep 2017

This morning, newspapers picked up on ‘game-changing’ results from trials of intensity-modulated radiation therapy (IMRT), released by The Institute of Cancer Research (ICR). The ICR reports that IMRT to lymph nodes in the pelvis can dramatically improve outcomes for patients with prostate cancer. But the claims being made in the newspapers are a little premature and have missed some important points.

The big benefit of IMRT is that it can be highly targeted to the tumor, sparing non-cancerous tissues nearby. This should mean higher doses of radiation can be given without dramatically increasing the side effects, for example in the bladder and bowel.

Survival rates actually no better than current treatments

Men on the trial were given IMRT to the lymph nodes of the pelvis to help stop the cancer spreading further. Giving standard radiotherapy in this area is usually considered too risky to give in high enough doses to be effective. The trial found this was safe using IMRT, that 87 per cent of the men on the trial were still alive five years after treatment and that the level of side effects was manageable.

What the papers missed is that survival rates along these lines are what we would expect with current treatments. Also, results have so far only been reported from phase one and two non-randomised trials. That means researchers have looked primarily at the safety of IMRT and a bit at the side effects and how well it works.

Randomised trials still ongoing but IMRT already in clinical use

Before a new treatment can be made available, it has to perform well in several different clinical trials. There are different phases from zero to four, which we’ve written about before. Trials can also be randomised or non-randomised. In a randomised trial, there are at least two groups of patients: often those who will get the treatment and those who won’t. People are put into the groups randomly. This is important to make sure that nothing in the way people are chosen for each group will affect the results – for example, patient age, gender or even how well they feel.

Because it’s been proven to be safe, IMRT to the pelvic lymph nodes is already being used in a number of cancer centres across the UK. However, it is still being tested in a randomised phase two trial. The way IMRT is tested in that trial has been informed by these results, but it is only when that trial is complete – in around two years’ time – that we will have a clearer picture of the impact of this new treatment on men. And it is then that we’ll be able to properly weigh up the slight increase in side effects against the benefits of giving a higher dosage.

We look forward to the conclusive trial results when published

"Radiotherapy is an effective and important treatment option for men with prostate cancer," says Dr Matthew Hobbs, our deputy director of research. "It's hugely important that researchers continue to look for new techniques that will allow us to drive up the benefit from radiotherapy while minimising the side effects suffered. And this promising study is exploring one approach to achieve this sort of improvement.
 
"However, today's findings need to be tested in larger randomised trials before we can get the definitive answers men need about whether this new technique is right for them. Those large-scale trials are now ongoing and we look forward to hearing the results and working with the researchers involved to take any positive results forward."

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