Collaboration May Expedite ctDNA Use and Inform Adjuvant Rectal Cancer Care

Nicholas Hornstein, MD, PhD, spoke with CancerNetwork^® at the 2026 ASCO Gastrointestinal Cancers Symposium about the importance of expanding serial circulating tumor (ctDNA) testing among patients who undergo surgery for rectal cancer, which may help on the back end of care and inform adjuvant therapeutic decisions. He spoke in the context of recently published findings from the GALAXY study (UMIN000039205) showing that postoperative ctDNA may be a robust biomarker that predicts the risk of recurrence and benefit of adjuvant chemotherapy among patients with resectable rectal cancer.

According to Hornstein, an assistant professor at the Donald and Barbara Zucker School of Medicine of Hofstra University and Northwell Health, bringing surgical oncologist colleagues into the discussion may expedite the development of ctDNA assays, thereby providing results much sooner to help guide adjuvant treatment decision-making. Although ctDNA may not be universally applicable, Hornstein noted that the biomarker may particularly help in the treatment of those with stage II colon cancer.

Transcript:

Communication and focusing on the multidisciplinary aspects of care is so critical. A lot of times, I’ll see a patient in clinic, and it’ll be a few weeks after they’ve had their curative intent surgery. I need to make the adjuvant chemotherapy decision then and there. I don’t have another month to wait for a tumor-informed ctDNA assay result. If you can bring your surgeon into the mix and into the discussion, you can send your ctDNA sample earlier—not the blood sample, but the tissue sample—to start the assay development. That’s going to help you because on the back end, when you’re seeing the patient, you’re going to have the results much sooner to help guide your hand with adjuvant decision-making. [It is] not for everybody, but for the right patients. For example, stage II colon [cancer]? That can be helpful.

Reference

Ando K, Hamabe A, Nakamura Y, et al. Molecular residual disease and recurrence in rectal cancer patients undergoing upfront surgery: a prospective cohort study. Ann Surg. 2026;283(1):13-21. doi:10.1097/SLA.0000000000006948