ESTRO: Select breast cancer patients may be able to omit surgery following ablative radiation
MD Anderson Research News May 16, 2026
Patients in this trial eligible to avoid surgery had a disease control rate of 100% at a median follow-up of over three years
All eligible patients had early-stage HR+, HER2-negative breast cancer
Patient responses to endocrine therapy served as biomarkers for those likely to have a complete response following radiation
ABSTRACT 4177
A select group of patients with early-stage breast cancer were able to omit surgery with no tumor progression after three years, according to results of a Phase 2 trial of ablative radiation therapy and endocrine therapy led by researchers at The University of Texas MD Anderson Cancer Center.
The findings were presented today by Simona Shaitelman, M.D., professor of Breast Radiation Oncology, during a proffered paper session at the Congress of the European Society for Radiotherapy and Oncology (ESTRO 2026) and published in Radiotherapy and Oncology.
“Historically, treatment de‑escalation in breast cancer has focused on reducing hormone therapy duration or the amount of radiation,” Shaitelman said. “What’s exciting now is that advances in radiation delivery are opening the door to entirely new, non‑operative approaches that many patients have been asking about.”
Why are some patients potentially able to avoid surgery for breast cancer?
The potential for some patients to avoid surgery is possible because of significant advances on multiple fronts. Improvements in how radiation is delivered have allowed radiation oncologists to deliver higher, and more accurate, doses, which not only makes the treatment more effective but also decreases the number of visits required for patients.
At the same time, knowledge of breast cancer biology has evolved to the point where clinicians have a much better understanding of which patients are likely to respond to which types of treatment, and which combination treatments can be effective together.
In this subset of patients, initial treatment with endocrine therapy can shrink tumors and make them even more sensitive to radiation, improving the effectiveness of the radiation therapy to the point that some tumors can be eliminated without a need for surgery.
What are the key data from this trial?
In this trial, 20 patients with a median age of 71 underwent three months of endocrine therapy followed by radiation therapy delivered in five high-dose fractions. All patients had stage 1 unicentric hormone receptor positive (HR+), HER2-negative breast cancers with favorable tumor biology.
Of those, 19 patients underwent biopsies, with 10 (53%) demonstrating a pathologic complete response. In the patients who had a complete response and did not have surgery, no breast-cancer related deaths were reported, and the tumor control rate was 100% at a median follow-up of over three years.
Three significant biomarkers were observed that predicted responses. Patients with smaller tumor size after initial hormone therapy, those with greater volume reduction before radiation, and those with tumors that more strongly expressed estrogen were more likely to have complete responses.
What is next for this research?
According to Shaitelman, the data in this study warrant a larger multi-institutional study to further evaluate this approach. Additional research would better identify the most appropriate breast cancer patients who are both interested in and best served by a non-operative approach.
“Radiation therapy is widely accessible around the world, yet its full potential as a definitive treatment for breast cancer hasn’t been fully explored,” Shaitelman said. “With more than two million women diagnosed each year, patients have varied goals and preferences, and it’s critical that we rigorously study non-surgical options to see whether they can deliver outcomes comparable to standard breast surgery.”
A full list of authors and their disclosures can be found in Radiotherapy and Oncology and with the abstract.