When someone has been treated for cancer, there are several monitoring tools doctors use to detect cancer remaining in the body. This information is IMPORTANT for the oncologist to decide:
Is there a need for (additional) cancer treatment?
How is the patient responding to treatment?
Are there any signs that the cancer has returned or progressed?
The most common imaging tools used to detect the presence of cancer are computerized tomography (CT) scan, magnetic resonance imaging (MRI), positron emission tomography (PET) scan, mammography, and X-ray. However, these imaging tools are limited in their ability to detect very small traces of cancer in the blood called molecular residual disease (MRD). Left untreated, small residual cancer cells may lead to recurrence.
Molecular residual disease is the presence of small traces of cancer in the blood, such as circulating tumour DNA (ctDNA) or microscopic pieces of tumour DNA.