The CRC10 colon cancer trial looks at ctDNA to identify the right treatment after surgery.

Researchers are leveraging new technology to identify tiny amounts of cancer cell DNA in the blood (circulating tumour DNA – ctDNA) as an indicator of the presence of otherwise undetectable numbers of residual colon cancer cells after surgical removal of the main tumour.

“While the data is very clear that patients who test positive for ctDNA after surgery have a much greater risk of their cancer recurring than those who test negative, we do not yet know whether ctDNA-positive cancers benefit from more intensive or longer chemotherapy or whether ctDNA-negative cancers even require chemotherapy," says Dr Jonathan Loree, CRC10 Canadian Study Chair and Medical Oncologist at BC Cancer.

The goal of the research is to determine whether and how using this information about the presence or absence of ctDNA may allow them to make better decisions about what kind and amount of chemotherapy to recommend to patients after surgery for colon cancer.

"As chemotherapy comes with substantial toxicity and potentially long-term side effects for patients as well as higher costs to the healthcare system, there is a real need to answer these questions," says CCTG senior investigator Chris O'Callghan. “Using ctDNA may lead to a reduction of chemotherapy in patients who do not need it and to escalate treatment intensity in those with an extremely high chance of cancer returning after surgery.”