The problem

When an individual has cancer, the disease needs to be monitored in order to see how it is responding (indeed, if it is responding) to the treatment. Unfortunately, the methods that we currently use to monitor cancer aren't terribly effective. For example, biopsies (a sample of tissue taken from the body in order to examine it more closely) only provide a snapshot—they allow us to only see a small portion of the disease, not the overall picture. Fortunately, these methods may soon change. Scientists from the University of Cambridge recently found that tumor DNA shed into the bloodstream can be used to track cancers in real time, meaning that we can watch as they evolve and respond to treatment.

A Way to Fight Back

For the research, scientists took biopsies and blood samples from a patient with breast cancer that had already spread to other organs. They then carefully studied small fragments of DNA that were shed into the blood by the dying tumor cells. These dead cells were compared with DNA from biopsies that were taken at the same time. Ultimately, the scientists found that the DNA in the blood samples matched the biopsies. In other words as the cancer developed and responded to treatment, both reflected the same pattern and timing of genetic changes. The team was even able to distinguish secondary cancers and examine how each of the individual tumors were responding to treatment.

In the end, the study shows that blood-based DNA tests can be used to track cancer progress in real time, potentially changing (and significantly improving) the way patients are monitored.

Blood extractions offer a far less risky alternative to repeatedly going under the knife, so using tumor DNA found in our blood could provide doctors with valuable insights into a patient’s disease without having to take repeated and invasive tumor samples. However, before we can have widespread implementation, the team needs to determine if the process works with other patients and other cancer types.

In any case, this is a great step forward.

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