ctDNA is “Here to Stay” as a Marker in Rectal Cancer Care

As far as rectal cancer management is concerned, circulating tumor DNA (ctDNA) is “not going anywhere”, and it is critical for practices to know how to use it optimally for patients, according to Nicholas Hornstein, MD, PhD.

In a conversation with CancerNetwork^® at the 2026 ASCO Gastrointestinal Cancers Symposium, Hornstein, an assistant professor at the Donald and Barbara Zucker School of Medicine of Hofstra University and Northwell Health, spoke about the implications of ctDNA becoming more widely adopted in rectal cancer care. Although current NCCN guidelines do not recommend routine use of ctDNA assays in colon or rectal cancers, Hornstein emphasized that these bodies must keep up with the latest data related to the biomarker so that they can be incorporated in a measured manner.^1,2

Hornstein spoke in the context of updated results from the GALAXY study (UMIN000039205), which showed the role that postoperative ctDNA could play in predicting recurrence risk and potential adjuvant chemotherapy benefit among patients who undergo upfront surgery for rectal cancer.³ Data published in Annals of Surgery showed that patients with ctDNA positivity after surgery had a significant disease-free survival benefit with adjuvant chemotherapy (HR, 0.28; 95% CI, 0.09-0.89; P = .031); those with ctDNA negativity saw no significant benefit (HR, 0.59; 95% CI, 0.26-1.35; P = .211).

Transcript:

The NCCN guidelines are absolutely critical. From one perspective, they help us with payers and insurance companies to make sure things are being covered. On the other hand, they’re making sure we’re giving the right KRAS assessment by expert opinions. Not everyone is a total nerd like me and can sit down and read through a dozen studies a week. In that respect, we need to see these bodies keeping up with the data and incorporating things in a measured manner. At the end of the day, ctDNA is here to stay. It’s had a huge uptake throughout both the academic and community [centers], and it’s probably not going anywhere. Now, we need to know how to use it best for our patients.

References

1. NCCN. Clinical Practice Guidelines in Oncology. Colon cancer, version 5.2025. Accessed January 12, 2026. https://tinyurl.com/5fc3vt7p
2. NCCN. Clinical Practice Guidelines in Oncology. Rectal cancer, version 4.2025. Accessed January 12, 2026. https://tinyurl.com/4a6drj3y
3. 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