Analysis of tumour DNA from blood could predict bowel cancer recurrence

An experimental DNA test could help predict which early-stage bowel cancer patients are at a greater risk of their disease returning following surgery, according to researchers in Australia and the US.

The team hopes that further research will eventually pave the way for the ‘liquid biopsy’ approach to be used routinely as a way to help doctors make decisions around treatment.

Scientists from the University of Melbourne and the John Hopkins Kimmel Cancer Centre in the US used blood samples to monitor 230 stage 2 bowel cancer patients following surgery. Their analysis included patients from 13 Australian hospitals.

Based on an initial tissue sample taken during surgery, the team identified at least one cancer-related gene fault in the patients’ tumours. They then fished for this gene fault in blood samples taken between four and 10 weeks after surgery and then every three months for up to two years.

The blood analysis detected fragments of the tumour DNA in 20 of the patients following surgery, according to the study published in the journal Science Translational Medicine. Six of these patients had received chemotherapy after surgery, while the other 14 had not.

Among those 14 patients who didn’t receive chemotherapy, 11 (79%) saw their disease return after 27 months of follow-up. This, the researchers believe, suggests that finding tumour DNA in the blood indicates that a recurrence of the disease could be “very likely”.  

Professor Jacqui Shaw, a Cancer Research UK expert in tumour DNA analysis, said the study was another “great example” of how this type of DNA analysis could one day help doctors monitor their patients.

“Through their ‘liquid biopsy’ approach, the researchers were able to accurately predict which patients were at high risk of their disease coming back after surgery,” she said.

“They also showed that repeat blood tests could help spot whether a patient is responding to chemotherapy after surgery or not.”

But the researchers cautioned that this, and other DNA-based blood tests “are not perfect”.

Current prediction methods mean patients deemed at high-risk of their disease returning may also receive chemotherapy after surgery. But experts believe that better methods are needed to make these predictions.

“Most patients with stage 2 colon cancers will be cured of the disease after surgery alone,” said Professor Bert Vogelstein, co-director of the Ludwig Center at the Johns Hopkins Kimmel Cancer Center and a member of the research team. 

“However, some of these cancers will recur, and we need to improve our diagnostic approaches to detect recurrence earlier than it can be found with current, conventional methods,” he added.

If these findings are confirmed in larger studies, researchers hope this type of genetic analysis could offer an additional way for doctors to decide which patients require additional treatment.

“In the future this could help doctors decide which treatments to offer patients with a positive blood test result, and potentially save those who test negative from extra treatment and side-effects,” added Professor Shaw.

A number of centres in the UK are also looking into this technology. But more research is needed before this type of test is ready for clinical use.