Select Early-Stage Breast Cancer Patients Achieve Complete Response Without Surgery Following Ablative Radiation and Endocrine Therapy
核心洞察
A phase II trial demonstrated that 53% of carefully selected early-stage breast cancer (搜索) patients achieved pathologic complete response with ablative radiation therapy (搜索) and endocrine therapy (搜索), allowing them to omit surgery entirely.
Patients who avoided surgery maintained 100% disease control with no breast cancer (搜索)-related deaths at a median follow-up of over three years, suggesting non-operative approaches may be viable for select cases.
Key biomarkers including smaller tumor size after hormone therapy, greater volume reduction before radiation, and stronger estrogen receptor (搜索) expression predicted complete responses to treatment.
A prospective phase II trial has demonstrated that carefully selected patients with early-stage breast cancer (搜索) can achieve complete tumor elimination through ablative radiation therapy (搜索) and endocrine therapy (搜索) alone, potentially avoiding the need for surgery entirely. The findings, presented at the Congress of the European Society for Radiotherapy and Oncology (ESTRO 2026), represent a significant advancement in treatment de-escalation strategies for breast cancer.
Trial Design and Patient Population
The study enrolled 20 patients with hormone receptor (搜索)-positive, HER2 (搜索)-negative, stage I nonlobular breast cancer (搜索) who met strict eligibility criteria. All participants were aged 50 years or older and had Oncotype DX scores of 25 or below, indicating favorable tumor biology. The treatment protocol involved 3 months of endocrine therapy (搜索) followed by definitive ablative radiotherapy delivered as 37.5 Gy in five fractions every other day.
"Historically, treatment de-escalation in breast cancer (搜索) has focused on reducing hormone therapy duration or the amount of radiation," said presenting author Simona Shaitelman, MD, Professor of Breast Radiation Oncology at The University of Texas MD Anderson Cancer Center. "What's exciting now is that advances in radiation delivery are opening the door to entirely new nonoperative approaches that many patients have been asking about."
Promising Response Rates and Long-Term Outcomes
Of the 19 patients who underwent percutaneous vacuum-assisted, image-guided core biopsy (VAIGCB) 6 to 12 months after radiotherapy, 10 patients (53%) achieved a pathologic complete response (95% confidence interval = 30%-73%). The pathologic complete response rate varied by timing, with 45% (95% CI = 19%-72%) for biopsies performed within 6 months of radiation and 63% (95% CI = 27%-87%) for those done within 12 months.
The long-term outcomes for patients who omitted surgery were particularly encouraging. At a median follow-up of 37.3 months, the disease progression rate was 0% among patients who achieved complete response. The 3-year progression-free survival rate reached 92% (95% CI = 54%-99%), with one patient death attributed to non-breast cancer (搜索)-related causes.
Predictive Biomarkers Identified
The study identified several significant biomarkers that predicted treatment response. While baseline tumor volume assessed by ultrasound did not correlate with pathologic complete response status (P = .29), both the tumor volume at 3 months after endocrine therapy (搜索) (P = .02) and the percent volume decrease from baseline (P = .04) showed significant correlations with complete response.
Additional biomarkers included 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 receptors were more likely to achieve complete responses.
Technical Advances Enable New Approaches
The study leveraged advanced radiation delivery techniques, with 80% of patients treated using a magnetic resonance linear accelerator when possible, while the remainder received treatment with a linac with computed tomography on rails. These technological improvements allow radiation oncologists to deliver higher and more accurate doses while reducing the number of treatment visits required.
The potential for surgery omission is made possible by the synergistic effect of endocrine therapy (搜索) and radiation. Initial treatment with endocrine therapy can shrink tumors and make them more sensitive to radiation, improving the effectiveness of radiation therapy to the point where some tumors can be eliminated without surgical intervention.
Implications for Future Treatment Paradigms
"Radiation therapy is widely accessible around the world, yet its full potential as a definitive treatment for breast cancer (搜索) hasn't been fully explored," Dr. Shaitelman noted. "With more than two million women diagnosed each year, patients have varied goals and preferences, and it's critical that we rigorously study nonsurgical options to see whether they can deliver outcomes comparable to standard breast surgery."
The researchers indicate that these data warrant a larger multi-institutional study to further evaluate this approach and better identify the most appropriate breast cancer (搜索) patients who are both interested in and best served by a non-operative approach. This research represents a potential paradigm shift in breast cancer treatment, moving beyond traditional de-escalation strategies to explore entirely new treatment pathways for carefully selected patients.