Stereotactic Radiotherapy for Oligoprogressive ER+/HER2- Metastatic Breast Cancer to Extend Systemic Therapy: A Prospective Phase 2 Study

What this Trial Is About

This research targets women with ER+/HER2- metastatic breast cancer who have been treated with endocrine therapy and/or CDK4/6 inhibitors for at least six months but now show disease progression in one to three extracranial metastatic sites that can be treated locally. The trial aims to find out if treating these resistant metastases with stereotactic body radiotherapy (SBRT) or other local therapies can extend the effectiveness of the current systemic treatments. The study explores whether this approach can delay the need to change systemic therapy and improve management of metastatic breast cancer. Participants will continue their existing systemic hormonal or CDK4/6 inhibitor therapy while receiving SBRT on all progressive lesions. If new oligoprogressive lesions appear, SBRT will be repeated. A new systemic treatment line will begin if the disease progresses with more than three lesions at once, over six lesions within 12 months, brain metastases, or lesions that cannot be treated locally. This approach allows ongoing systemic therapy to be maintained as long as possible while addressing resistant metastases locally. During the study, participants will be monitored for survival without changing systemic therapy six months after SBRT, along with several secondary outcomes such as time to next systemic therapy, progression-free survival, chemotherapy-free survival, and quality of life over three years. Researchers will also evaluate treatment-related toxicity and patterns of metastatic progression. The study involves regular assessments and follow-up to evaluate the impact of local treatment on disease control and patient well-being.

Stereotactic Radiotherapy for Oligoprogressive ER+/HER- Metastatic Breast Cancer, a Prospective Phase 2 Study (Oligopro-Breast)