Overview
- The phase II EXTEND trial, presented at ESTRO 2026 and published in the Journal of Clinical Oncology, evaluated a blood test that measures circulating tumor DNA to guide care.
- Researchers enrolled 237 patients with one to five metastases across six tumor-type groups and randomized them to drug therapy alone or drug therapy plus high-precision, metastasis-directed radiotherapy.
- Adding targeted radiotherapy improved overall cancer control and increased clearance of tumor DNA from blood compared with drug therapy alone.
- Patients who had detectable tumor DNA in their blood at the start faced higher risks of progression and death than those without it.
- After treatment, cleared tumor DNA tracked with much better outcomes, and lingering tumor DNA signaled aggressive or hidden disease that could prompt therapy changes now being studied.