A study looking at melanoma skin cancer cells in the bloodstream

Cancer type:

Skin cancer





Cancer spreads when cells break from the first cancer growth and travel through the bloodstream to another part of the body. 

This study looked at whether doctors could find cancer cells in the bloodstream of people with advanced melanoma.

More about this trial

Cancer cells that travel in the bloodstream are called circulating tumour cells (CTCs). Scientists have known for a long time that cells do this. But it is only recently that they have they been able to study them easily. 

In some cancers, it is possible to find and count circulating tumour cells. Researchers have found that the higher the number of CTCs someone has, the more likely it is that they will not do very well. And the more CTCs are reduced after treatment, the better someone will do.

Doctors wanted to see if counting CTCs worked for melanoma. They also wanted to look for features in these cells that might help them develop more suitable treatment. And learn more about how cancer cells spread

If successful, a simple blood test rather than a tissue sample (biopsy Open a glossary item) might be able to be used to diagnose melanoma earlier. Or to find out what was happening with the cancer once diagnosed. 

The main aims of this study were to:

  • count and study circulating cancer cells in people with melanoma that had spread
  • see if CTCs could be used to predict how well treatment would work

Summary of results

The study team found the number of CTCs in the blood can help them predict how long people might live after treatment. 

The team used a test called the CELLSEACH CTC test to look for the number of melanoma CTCs in the blood. CELLSEARCH CTC can reliably count 2 melanoma CTCs in 7.5 ml of blood so it is very precise. 

101 people took part in the study. 

Blood samples were taken before they started treatment, at regular times during treatment and after treatment. 

Before treatment CTCs found ranged between 0 and 36 in 7.5 ml of blood. The average number of CTCs was 2 in 7.5 ml of blood. 

  • 60 out of every 100 people (60%) didn’t have any CTCs in their blood
  • 40 out of every 100 people (40%) had 1 or more CTCs in their blood 

The team found that a cut off of 2 CTCs in 7.5 ml of blood showed the greatest difference in the average length of time people lived after treatment (their overall survival). 

The team split the 101 people into 2 groups according to how many CTCs were in their blood. 

  • 75 people had less than 2 CTCs. This was the ‘favourable’ group
  • 26 people had 2 or more CTCs. This was the ‘unfavourable’ group

The team looked at the average length of time people lived in each group. They found it was:

  • just over 7 months for those in the favourable group
  • just over 2½ months for those in the unfavourable group

study diagram

During treatment researchers wanted to know if there was a link between the numbers of CTCs and how well the melanoma responded to treatment. 

After 6 to 9 weeks of treatment everyone had a CT scan Open a glossary item. Blood samples were also taken at this time so the team could count the CTCs. 

The CT scan of 13 people showed their melanoma had responded to treatment. The CTCs of these people had also decreased.  

The team concluded that CTCs could be counted in the blood of people with advanced melanoma and that this can help to predict how long people might live. There is also early evidence that changes in the numbers of CTCs during treatment could reflect how well treatment will work. More detailed studies are needed to look at this. 

We have based this summary on information from the research team. 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.

Recruitment start:

Recruitment end:

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.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Dr Paul Lorigan

Supported by

Cancer Research UK
Experimental Cancer Medicine Centre (ECMC)
The Christie NHS Foundation Trust
University of Manchester

If you have questions about the trial please contact our cancer information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Around 1 in 5 people take part in clinical trials

3 phases of trials

Around 1 in 5 people diagnosed with cancer in the UK take part in a clinical trial.

Last reviewed:

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