Liquid biopsy analysis helps improve cancer monitoring

Researchers at the University of Zurich (UZH) and the University Hospital Zurich (USZ) have developed a way to analyse DNA fragments in the blood of cancer patients, which could lead to diagnostics and treatments that are more closely tailored to individual patients. Their work has been published in the journal Radiotherapy & Oncology.

The earlier a cancer is detected, the better the chances that treatment will be effective. Another crucial element in successfully treating patients is to individually assess the benefits and risks of individual forms of therapy and to regularly monitor treatment success. To do this, oncologists have a range of methods at their disposal, most notably imaging technology and invasive measures such as tissue biopsies, punctures and endoscopic procedures.

The Zurich researchers have now developed a liquid biopsy method that sequences and analyses DNA fragments circulating in the blood of patients. Since the method is based on blood samples, rather than organs or tissues, it is less invasive than performing tissue biopsies. Moreover, taking blood samples is faster and more practical in day-to-day hospital operations, as fewer appointments for diagnostic interventions are needed.

The new method can help oncologists to more accurately determine tumour activity and spread, which will enable them to develop therapies that are tailored to individual patients. As explained by co-first author Zsolt Balázs, from UZH, “We can see earlier and more quickly how much the cancer has spread in the body and how well a patient is responding to a specific treatment, or whether there will be a relapse.

“Our method can be used in the future for risk assessments, treatment monitoring during follow-up care and early detection of cancer recurrence, in principle for all types of tumours.”

The researchers examined the gene fragments circulating in the blood for changes in the DNA that are characteristic of the specific type of cancer, with their method analysing alterations in the number and length distribution of the fragments. As explained by co-first author Professor Panagiotis Balermpas, from USZ, “The liquid biopsy technique enables us to discriminate between biologically less and more aggressive metastatic cancer disease — perhaps even earlier than using imaging technology.”

The researchers tested their method on patients undergoing radiotherapy, including several HPV-positive patients. The number of HPV DNA fragments found in the blood allowed the researchers to observe the development of tumours. For head and neck cancer, they found that a higher concentration of HPV DNA might be an early indication of cancer recurrence, which could be combated using immunotherapy.

“The more a tumour metastasises, the poorer the patient’s quality of life; this also applies to local recurrences that aren’t detected early,” Balermpas said. “It is key that we individualise treatment as far as possible, taking into account the potential benefits of all therapies as well as their influence on the patient’s quality of life.”

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