Blood test could determine if a cancer is likely to spread – and how fast

A new blood test could determine which cancer patients have a higher risk of their disease spreading, according to new research. 

The test, developed by British researchers, analyzes fragments of DNA that are shed by tumors into the bloodstream.

In a study on 47 patients with rectal cancer, they found the test accurately predicted whose cancer would spread over the next two year, spotted 74 percent of them before they had even started treatment. 

Experts say the report, presented at a conference today, is encouraging, but time will tell how pivotal it is in the context of countless other studies and start-ups trying to find a liquid biopsy to detect cancer and aggressive cancer early.

‘We know patients respond quite differently to standard treatment – some will do really well, and have what we call a complete pathological response,’ lead author Dr Shelize Khakoo, Medical Oncologist at The Royal Marsden NHS Foundation Trust, said. 

‘For others, the cancer may spread during treatment.

‘If we can predict early on who will go on to develop metastatic disease, we might be able to tailor treatment by making it more intense or trying an alternative.’ 

In this study, the researchers took liquid biopsies from 47 patients at The Royal Marsden who had localized rectal cancer, meaning it had not already spread to other body parts. 

Blood samples were taken before, during and after patients had completed chemotherapy and radiotherapy (CRT), and then again after surgery. 

They recorded ctDNA in 74 percent of patients before any treatment, and 21 percent of patients mid-way through CRT, 21 percent after CRT and 13 percent after surgery. 

The ctDNA results at the end of CRT were associated with tumor response to CRT as shown on MRI scans.

Following up around two years later, they found the blood test had been accurate. 

Those with traces of ctDNA were more likely to see their cancer spread beyond the rectum.

Those with ctDNA persisting throughout their treatment were more likely to develop metastatic cancer sooner.  

‘These results suggest that liquid biopsies offer us an accurate method of establishing the cancer’s activity throughout the body,’ said fellow lead author Professor David Cunningham OBE, Consultant Medical Oncologist at The Royal Marsden NHS Foundation Trust.

‘Importantly what this study showed, which has not yet been explored, is that persistence of ctDNA mid-way through treatment could be an early indicator of the cancer’s potential to spread. 

‘Using this measure, along with MRI scans, we can offer a more personalized treatment approach for patients.’

Dr Khakoo added: ‘Whilst our findings are interesting and exciting, it’s important to note that this was carried out in a small cohort of patients and would require further validation in a larger trial.’