A study looking the dose and side effects of radiotherapy for prostate cancer and head and neck cancer (VoxTox)

Cancer type:

Brain (and spinal cord) tumours

Head and neck cancers

Prostate cancer

Status:

Results

Phase:

Other

This study looked at the amount of radiotherapy which reached healthy cells around the cancer. It also looked at the side effects people had. It was for people with prostate cancer or head and neck cancer.

The study was open for people to join between 2013 and 2019. The team published some results in 2017 and more in 2020.

More about this trial

Doctors use radiotherapy to treat many types of cancer. They plan it very carefully to target the exact size, shape and position of the cancer.

The aim is to avoid healthy tissue nearby. But it can still cause some damage to the healthy tissue around area of cancer. And this can cause side effects.

This could mean there is some damage to the:

back passage (rectum) during radiotherapy for prostate cancer
salivary glands during treatment for head neck cancer

The main aims of this study were to find out:

how much radiotherapy reaches the healthy tissue around the area of cancer
if this is linked to the side effects people have

Summary of results

The research team found that the side effects people have could be linked to the amount of radiotherapy that reaches healthy cells.

Study design
This study was for people with prostate cancer or head and neck cancer. They were due to have radiotherapy as part of their treatment.

The research team compared how much radiotherapy:

doctors predicted would reach healthy tissues around the cancer
actually reached healthy tissues around the cancer by the end of treatment

They then looked at the side effects. They wanted to see if there was a link between the side effects and the predicted or actual radiotherapy dose.

Results for people with prostate cancer
The research team looked at the results for 109 people who had radiotherapy for prostate cancer. They looked at the radiotherapy dose people had, and the number of people who had side effects such as:

bleeding from the back passage
inflammation of the bowel (proctitis)

The research team found that there was a difference between:

the amount of radiotherapy the doctors thought would affect healthy tissue
the amount of radiotherapy that actually did affect healthy tissue by the end of treatment

There was a bigger link between the actual dose of radiotherapy that reached the healthy tissue, and the side effects people had.

There was less of a link between the amount of radiotherapy doctors thought would reach healthy cells, and the side effects people had.

The researchers hope this will:

lead to a way of improving how radiotherapy is planned
reduce side effects of treatment

Results for people with head and neck cancer
The research team looked at the results for 198 people who had radiotherapy for head and neck cancer. This included people with larynx (laryngeal) cancer, mouth cancer or oropharyngeal cancer.

They looked at the radiotherapy dose people had, and the number of people who had side effects such as:

dry mouth
inflammation
difficulty swallowing

There was only a slightly bigger link between the actual dose that reached the healthy tissue, and the side effects people had. This is compared to the dose that doctors thought would reach healthy tissue.

The team suggest only a small number of people would benefit from changing the shape and size of the radiotherapy during treatment. This is called adaptive radiotherapy.

Where this information comes from
We have based this summary on information from the research team. Some of the information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item ) 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.