CANCER ADVANCEMENT: New way of detecting cancer has been discovered
A 'liquid biopsy' blood test that will detect childhood cancers leading to personalised treatment has been developed by scientists.
The method, doing away with surgery, checks whether patients have bits of tumour DNA in their blood and uses them to monitor how they respond to treatment, according to a new study.
Cancer cells in tumours are constantly dividing, but some of them die in the process and release bits of DNA into the bloodstream.
By analysing these genetic fragments, doctors can diagnose and monitor the tumour’s development.
Liquid biopsies, sampling and analysing bodily fluids, are far less invasive than conventional tumour biopsies, which often require surgery.
But using this method in children has proven difficult as few of the tumour’s genetic alterations are detectable in floating bits of DNA.
Now scientists have come up with a new way of tracking these changes which could improve diagnosis and, in the long run, treatment.
Lead author Dr Eleni Tomazou at St. Anna Children's Cancer Research Institute in Austria said: “We previously identified unique epigenetic signatures of Ewing sarcoma.
“We reasoned that these characteristic epigenetic signatures should be preserved in the fragmentation patterns of tumour-derived DNA circulating in the blood.
“This would provide us with a much-needed marker for early diagnosis and tumour classification using the liquid biopsy concept.”
A rare type of bone cancer known as Ewing sarcoma, which mainly affects children and young adults, was studied by the researchers.
They discovered the size of fragments circulating in the blood was not random or solely determined by the DNA sequence.
Rather, it depended on how the DNA was packaged inside the cancer cells and their epigenetic profile.
A cell’s epigenetic profile refers to what genes are turned on by interactions between its DNA and a substance called chromatin.
These epigenetic patterns, sometimes referred to as the “second code” of the genome, are distinctive for different cell types in the human body.
Analysing them allowed the researchers to monitor epigenetic regulations inside the tumour itself without having to perform surgery.
This means doctors will be able to test for cancer without knowing whether there is a tumour in their patient’s body and where it is.
The researchers have also benchmarked various metrics to help doctors analyse the DNA fragments.
This includes an algorithm dubbed LIQUORICE which detects circulating tumour DNA in the blood and therefore whether a patient has cancer.
Dr Tomazou said: “By feeding these machine learning algorithms with our extensive whole genome sequencing data of tumor-derived DNA in the blood stream, the analysis becomes highly sensitive and in many instances outperforms conventional genetic analyses."
The new approach could improve cancer diagnosis and lead to the development of personalised forms of therapy, although more research is still needed.
Dr Tomazou said: “Our assay works well, we are very excited.
“However, further validation will be needed before it can become part of routine clinical diagnostics.”
It could also be used to determine which patients are responding to treatments such as chemotherapy, allowing doctors to adjust their doses.
Dr Tomazou said: “Right now, most patients receive very high doses of chemotherapy, while some patients may be cured already with a less severe therapy, which would reduce their risk of getting other cancers later in life.
“There is a real medical need for adaptive clinical trials and personalized treatment of bone tumours in children."
The findings were published in the journal Nature Communications.
Words: Tom Campbell, South West News Service
Watch the channel on TV