Intraoperative Radiation Therapy

News coverage in the fall of 2025 discussed a treatment for breast cancer called intraoperative radiation therapy (IORT) which delivers a single, targeted radiation dose to a patient’s breast tissue immediately after surgery to remove a tumor. Much of the coverage mischaracterized why ASTRO doesn’t support IORT outside of a clinical trial or registry for people with breast cancer.

ASTRO strongly supports accelerated, partial breast irradiation (PBI) techniques for many patients with early-stage breast cancer, as outlined in our 2024 PBI guideline in collaboration with the Society of Surgical Oncology and American Society of Clinical Oncology, but IORT, while promising in concept, has not yet met the evidentiary threshold required for guideline inclusion. Current data on IORT remains insufficient compared to other PBI techniques such as external beam radiation therapy and brachytherapy.

This position was also formally reflected in a resource guide from the American Society of Breast Surgeons, reinforcing ASTRO’s concerns about long-term outcomes, recurrence risk and the potential need for additional treatment after IORT. You can read ASTRO’s full statement about IORT and our guideline development process.

We encourage patients to talk with their oncologists to understand which treatment options may be best for them.