A new study suggests that a personalized blood test called tumor-informed circulating tumor DNA (ctDNA) may help doctors predict which people with anal squamous cell carcinoma (anal cancer) are most likely to have their cancer come back after chemoradiation.
Key message for patients
- Researchers found that patients whose ctDNA was still detectable in the blood at the end of chemoradiation had a much higher risk of the cancer returning and poorer one-year survival compared with those whose ctDNA became undetectable.
- Patients who either started out ctDNA‑negative or cleared ctDNA during treatment had excellent outcomes, with no local cancer regrowth seen in this group at one year.
What the study did
- The study followed 84 adults with non‑metastatic anal squamous cell carcinoma who received standard chemoradiation with curative intent at two cancer centers.
- Blood samples (647 in total) were tested using a tumor‑informed ctDNA assay (Signatera), which is customized to each person’s tumor to look for tiny fragments of cancer DNA circulating in the blood.
What the researchers found
- Before treatment, ctDNA was detectable in about 8 out of 10 patients overall and in nearly 9 out of 10 patients with stage III disease, showing that this blood test can pick up cancer DNA even in earlier stages.
- At the end of chemoradiation, patients who still had ctDNA in their blood had worse one‑year outcomes (about 63% overall survival and 44% progression‑free survival) and more local treatment failures, while those who cleared ctDNA had far better results and no local failures at one year.
Why this matters
- For patients and care teams, ctDNA testing could offer an earlier and more precise signal of whether chemoradiation is working, long before changes are visible on scans or exams.
- The study also showed that ctDNA “re‑emergence” during follow‑up always happened before the cancer was seen on imaging or physical exam, suggesting ctDNA could be used to tailor how closely someone is monitored and who might benefit from earlier additional treatment.
What this could mean for future care
- These findings support ctDNA as a dynamic biomarker that responds to treatment and may help doctors personalize follow‑up schedules and decide who might need extra therapy after chemoradiation for anal cancer.
- The authors emphasize that more research in larger, prospective trials is needed before ctDNA‑guided care becomes routine, but this work is an important step toward more individualized surveillance and treatment planning for people with anal squamous cell carcinoma.
More Reading
Romesser PB, Bercz A, Alvarez J, et al. Tumor-informed circulating tumor DNA stratifies recurrence risk and survival in anal squamous cell carcinoma. Nat Commun. 2026 Feb 26.
