Liquid biopsies to monitor cancer


Being able to easily track cancer is vital in all stages of the disease. Doctors have long been able to monitor the disease with scans and by taking small tissue samples (biopsies), but now a new technique is becoming available to them: the liquid biopsy, which can deliver a lot of detailed information about a patient's tumour from a simple blood sample.


So how does it work? Inside a tumour, cells are growing at a high rate, but while many cancer cells are growing, some are also dying in a process called apoptosis. As dying cancer cells break up, they release fragments of their DNA. Some of that DNA can get into the blood stream, after which it's called circulating tumour DNA (or ctDNA). This circulating tumour DNA is ready for scientists to fish out with a simple blood sample.


Because of advances in DNA sequencing technology, doctors can pick up on these traces of DNA, and use them to track the mutations present in a cancer. Finding out this information helps doctors keep track of a patient's tumour and whether treatment is working, or find out early if a new scan or different treatment is needed.


Credit to: Cancer Research UK and Phospho Biomedical Animation