A trial of radiotherapy for cancer that has spread to another part of the body (SABR-COMET)

The results showed that stereotactic ablative radiotherapy (SABR) helped stop cancer growing and meant people lived longer. But it also caused more side effects.

Trial design
Everyone taking part in this trial had cancer that had spread to up to 5 other areas of the body. These areas included the lungs, bone and liver.

The people who joined the trial were put into 1 of 2 treatment groups at random. There were twice as many people in the SABR group as there were in the standard treatment group. This is called 2:1 randomisation.

Results
A total of 99 people joined this trial and were put into 1 of 2 treatment groups. There were:

• 33 people in the standard treatment group
• 66 people in the SABR group

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• 1 area in 42 people
• 2 areas in 32 people
• 3 areas in 18 people
• 4 areas in 4 people
• 5 areas in 3 people

The research team looked at how long it was before people’s cancer started to grow again. They found it was longer for people who had SABR:

• 6 months for those who had standard treatment
• 12 months for those who had SABR

They then looked at how long people lived for, and found this was also longer for people who had SABR:

• 28 months for those who had standard treatment 
• 41 months for those who had SABR

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• 16 out of 33 people (48%) who’d had standard treatment
• 24 out of 66 people (36%) who’d had SABR

The research team looked at the change in size of 157 specific areas of cancer, to see if they’d grown after treatment or not. The number of areas of cancer that had not grown was:

• 28 out of 57 (49%) in the standard treatment group
• 75 out of 100 (75%) in the SABR group

Quality of life
The research team measured changes in people’s quality of life using several different questionnaires. The people taking part completed these questionnaires before, during and after treatment. 

The research team found there wasn’t any difference in the results between those who had standard treatment and those who had SABR.

Side effects
People in both groups had some side effects. But more people who had SABR had moderate or severe side effects:

• 3 people (9%) who had standard treatment
• 19 people (29%) who had SABR

Doctors think 3 people who had SABR died because of the treatment, rather than because their cancer had grown. Two had lung infections and one died following an operation to help with a stomach ulcer caused by the radiotherapy. 

No one in the standard treatment group died because of the treatment they had.

Conclusion
The research team concluded that SABR did help stop the cancer growing and meant that people lived longer. But it also caused more side effects.

They recommend that more trials are done to find out more about how well SABR works for specific cancer types. And that it might to useful to find out if there is a maximum number of areas of cancer spread where SABR is helpful.

Where this information comes from    
We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed ) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.