Pashtoon M. Kasi, MD, MBBS, MS, discusses the prognostic value of circulating tumor DNA in colorectal cancer.
Pashtoon M. Kasi, MD, MBBS, MS, assistant professor of oncology, senior associate consultant, Division of Hematology/Oncology, Mayo Clinic, discusses the prognostic value of circulating tumor DNA (ctDNA) in colorectal cancer (CRC).
Investigators have shown that the presence of ctDNA after curative-intent surgery or multimodality treatment in patients with CRC may be an indicator for relapse, says Kasi.
ctDNA is typically tested 2 to 4 weeks following surgical resection. Patients who are ctDNA-positive following surgery have a high likelihood of disease recurrence within 2 years, says Kasi.
Unlike carcinoembryonic antigen testing and carbohydrate antigen 19-9 testing, false positives are not common with ctDNA assays. In patients who are ctDNA-negative and recur, Kasi reasons that the results may reflect low tumor volume, tumor location, or a less sensitive assay.