Using ctDNA in Stage II Colon Cancer

Cristian Tomasetti, PhD, associate professor at the John Hopkins University School of Medicine, discusses the role of circulating tumor-DNA (ctDNA) after surgery in patients with stage II colon cancer.

According to findings from the phase 2 DYNAMIC study (ACTRN12615000381583), using a ctDNA approach in this patient population leads to a reduction in the use of adjuvant chemotherapy. This result was achieved without compromising recurrence-free survival.

Further, the use of ctDNA after surgery can help determine which patients may relapse and who may need adjuvant chemotherapy or not.

Transcription:

0:08 | It's been known now for some time that normal cells as well as cancer cells shed some of their DNA into the bloodstream. By measuring the levels of cell-free DNA, we may be able to detect some of these DNA fragments that don't come from regular healthy cells but come from cancer cells.

0:42 | The idea in this specific setting with colon cancer is that if the surgery was a success, and the cancer was fully removed, then after a few weeks, in theory, we shouldn't find any cell-free DNA coming from cancer cells, because the cancer has been fully removed, in theory.

1:17 | If instead, we do [find cell-free DNA from cancer cells] then that is a sign that there is still some cancer in the body of that patient. We can use this information to determine who we think are patients that will at some point relapse, because cancer cells are still present. They will proliferate and grow back to produce it and we call that a clonal expansion. Based on this information, we can think about who may need adjuvant chemotherapy or not.