Personalised circulating tumour DNA could have the potential to be the biomarker routinely used by oncologists treating patients with colorectal cancer, two new studies suggest.

The “exciting technology” may eventually be used to predict who will have recurrence after surgery; who should have adjuvant chemotherapy; and in assessing whether therapy has worked, say the authors of an editorial in JAMA Oncology discussing both pieces of research.

Both studies followed patients with stage I-III colorectal cancer over time, assessing the levels of circulating tumour DNA (ctDNA) released into their blood by cancer cells, as a patient progressed through treatment.

In the first study, carried out at Johns Hopkins University in the US and the Karolinska Institute in Sweden, 58 patients had their ctDNA measured 30 days after surgery for their colorectal cancer, and then every 3-6 months thereafter.