Cancer DNA in the Blood

After patients with Cancer undergo surgery to remove a tumour. Sometimes they also undergo chemotherapy, tools are used to identify patients at the highest risk of recurrence. Non-invasive tools to detect microscopic disease are of especially high value.

In a new study published in Clinical Cancer Research, a team led by investigators at Massachusetts General Hospital has evaluated the first tumor-uninformed test that detects cancer DNA circulating in the Blood of patients following treatment. The test is called Guardant Reveal which was developed by precision oncology company Guardant Health. It is tumor-uninformed because this test does not require knowing the particular mutations that were present in the patient’s tumor.

Aparna R. Parikh, MD, an investigator in the Division of Hematology and Oncology at MGH and an assistant professor of Medicine at Harvard Medical School and the lead author of the study said that the use of ctDNA, which is a type of liquid biopsy, is a powerful prognostic tool to detect residual disease, and many prospective trials are underway in the United States, Europe, Asia and Australia to use ctDNA to guide treatment decision-making. Many studies have used a tumor-informed ctDNA approach that requires testing of the tumor and knowledge of tumor-specific alterations, which can’t be used when a patient has insufficient tumor tissue for analysis.

In this study, Parikh and her colleagues at Massachusetts General Hospital and Guardant Health evaluated the first tumor-uninformed ctDNA assay to detect residual Cancer cells in patients who underwent surgery for colorectal cancer. They decided that instead of relying on DNA sequencing of individual patient’s tumors, the approach looked for known cancer-specific alterations.