Blood samples with circulating tumour DNA is a new tool with a large potential to monitor for recurrence of disease (photo: Tonny Foghmar, Aarhus University Hospital).

Researchers from Aarhus University Hospital and Aarhus University have discovered that tumour DNA in the blood can detect recurrence in patients with colorectal cancer up to 12 months earlier than existing methods. 

Colorectal cancer is one the most common and deadly types of cancer worldwide. Even though two thirds of the patients diagnosed are curable, approximately one third will experience recurrence of disease after treatment. 

It is decisive for survival that recurrence of disease is discovered as early as possible. The results of a new large study from Aarhus University Hospital and Aarhus University can help to ensure early diagnosis of recurrences in the future . 

Research shows that analysis of blood samples for circulating tumour DNA is a new tool with a large potential to monitor for recurrence of disease. Remaining cancer cells in the patient’s body release tumour DNA to the blood stream and this can be a way to reveal the presence of cancer cells in the patient. 

- It is characteristic for cancer cells that their genome in several ways is altered compared with the genome in normal cells. This means that the each patients tumour has unique alterations in its genome. Moreover, previous research has shown that these alterations frequently can be traced in the blood stream – acting as a kind of tumor marker, says Professor Claus Lindbjerg Andersen who is the primary investigator of the study. 

Improved chance of survival 
The researchers collected blood samples at regular intervals during a period of three years after the patients’ underwent surgery. By analyzing these longitudinally collected samples the researchers could measure alterations in the occurrence of tumour DNA in the blood. In all patients diagnosed with recurrence, tumour DNA was found in the blood stream before the patients experienced symptoms and long before it was diagnosed by the general surveillance programme. In some patients, tumour DNA was found in the blood immediately after surgery; this indicates that part of the tumour had not been removed during surgery. 

- This can be a huge step forward concerning improved survival. If the cancer returns the treatment can be initiated far earlier than today where recurrence often first is diagnosed when it is so advanced that it can not be cured , says Claus Lindbjerg Andersen. 

The analyses indicate that recurrence can be detected 10-12 months earlier in the blood compared with existing methods. This is critical for the efficiency of the treatment of the recurrence. Earlier diagnosis of recurrence is likely to improve patient survival. 

If the recurrence is detected early enough to allow the tumour to be removed surgically there is even a chance that patients can recover completely despite the recurrence. 

The researchers also demonstrated that the method can be used to evaluate the efficiency of e.g. chemotherapy, radiation therapy and surgical intervention. This is of importance as it allows for optimising and adapting the treatment of patients experiencing recurrence. 

Post doc. Thomas Reinert, Department of Molecular Medicine and PhD student Lone v. Schøler, Department of Molecular Medicine have performed the majority of the analyses in the study. The results are published in the highly estimated and internationally renowed journal GUT with the title: 

Analysis of circulating tumour DNA to monitor disease burden following colorectal cancer surgery. 

Thomas Reinert, Lone V Schøler, Rune Thomsen, Heidi Tobiasen, Søren Vang, Iver Nordentoft , Philippe Lamy, Anne-Sofie Kannerup, Frank V Mortensen, Katrine Stribolt, Stephen Hamilton-Dutoit, Hans J Nielsen, Søren Laurberg, Niels Pallisgaard, Jakob S Pedersen, Torben F Ørntoft, and Claus L Andersen. 

Further information: 
Claus Lindbjerg Andersen, Professor 
Department of Molecular Medicine 
Aarhus University Hospital 
Email: cla@clin.au.dk