Last year in the UK over 60,000 cancer patients enrolled on clinical trials aimed at improving cancer treatments and making them available to all.
A study looking at changes to DNA in people having radiotherapy
This study looked at the level of damage and repair in genetic material (DNA) in white blood cells after radiotherapy treatment.
More about this trial
Radiotherapy uses x-rays to destroy cancer cells. It works by causing damage to the DNA. DNA is the genetic code which tells cells how to grow and behave.
As well as damaging cancer cells, radiotherapy can also affect healthy cells near the treatment area. This can cause side effects.
The area of the body being treated and the dose of radiotherapy both affect the side effects people might have. The dose people need depends on where the cancer is, and how big it is.
Researchers in this study wanted to understand more about cell damage caused by radiotherapy.
To do this, they measured the amount of a specific protein called gamma H2AX in white blood cells, as a sign of the cell damage in the body generally. Cells produce more gamma H2AX if their DNA is damaged. So a higher level of this protein could mean there is more cell damage.
The aim of this study was to measure the level of DNA damage and repair in white blood cells after radiotherapy.
Summary of results
The study team found that the level of gamma H2AX protein did increase during radiotherapy treatment.
This study was open for people to join between 2008 and 2011, and the research team first presented results at a conference in 2010.
About this study
The research team took blood samples from 15 people having radiotherapy for a brain tumour. They had a type of radiotherapy called intensity modulated radiotherapy, or IMRT.
IMRT means the area of radiotherapy is shaped to the specific area of cancer. It is a way of giving more radiotherapy to the areas that need it, while protecting healthy tissue. But it can still affect healthy tissue.
Radiotherapy is split into doses called fractions. It is common to have several fractions a week for a few weeks.
The research team took blood samples from people in the study:
- when they joined the trial
- just before and 30 minutes after one dose (fraction) of radiotherapy each week
- 2 and 6 weeks after they finished treatment
They measured the amount of gamma H2AX protein in white blood cells to assess the level of DNA damage.
The results showed the level of gamma H2AX in white blood cells:
- was very low before people started treatment (baseline measurement)
- increased during the first week of radiotherapy
- did not increase much more as treatment went on
- went back to the baseline level by 6 weeks after treatment
These results suggest that radiotherapy does cause some DNA damage to healthy cells, but that the damage is repaired once treatment stops.
The research team concluded that measuring gamma H2AX is a useful way to assess DNA damage. And that DNA that is damaged by radiotherapy but is repaired after treatment.
They suggest that it might be useful to use gamma H2AX measurements to compare DNA damage caused by different types of radiotherapy.
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 (
How to join a clinical trial
Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.
Professor Susan Short
Experimental Cancer Medicine Centre (ECMC)
NIHR University College London Hospitals Biomedical Research Centre
University College London Hospitals NHS Foundation Trust