259 - Standard of Care Systemic Treatment with or without Stereotactic Body Radiation Therapy (SBRT) in the Management of Patients with Newly Diagnosed Extra-cranial Oligometastatic Breast Cancer (OMBC): A Prospective Randomized Study (NCT06144346)
Presenter(s)
J. Nayrouz1, M. El-Sebaie1, H. El-Marakby2, A. S. Gaber3, M. Bayomy4, and R. Boutrus1; 1Radiation Oncology Department, National Cancer Institute, Cairo University, Cairo, Egypt, 2Surgical Oncology Department, Breast Division, National Cancer Institute, Cairo University, Cairo, Egypt, 3Medical Oncology Department, National Cancer Institute, Cairo University, Cairo, Egypt, 4Clinical Oncology Department, Zagazig University., Zagazig, Egypt
Purpose/Objective(s):
To compare the response rate (RR), progression free survival (PFS) and quality of life for patients with OMBC treated with or without SBRT prior to standard of care systemic treatment.Materials/Methods: One hundred and forty patients with newly diagnosed breast cancer and 5 or less extra-cranial metastases were enrolled into the current study from January 1st, 2022 till May 30th, 2024. Patients were randomized to receive SBRT followed by 6 months of systemic therapy (SBRT arm, n=70) or systemic therapy alone (SOC arm, n=70). Stratification was done according to the biological subtype, site and number of metastases. Response was assessed with PET CT scan after six months of systemic treatment and graded according to RECIST1.1 criteria. Quality of life assessed at 6 months after treatment using Breast Cancer Treatment Outcome Scale (BCTOS).
Results:
Median follow-up was 12 months (range, 6-32). Forty-eight percent of the patients had bone metastases, 17.9% had lung metastases, 16.4% had liver metastases, 0.7% had adrenal metastases and 17.1% had a combination of multiple metastatics sites. In the SBRT arm, 28.2% had clinical complete response (CR), 32.4% had partial response (PR), 19.7% stable disease (SD), and 19.7% had progressive disease (PD). In the SOC arm, 29% had CR, 20.3% had PR, 24.6% had SD and 26.1% had PD. The difference in the response rate was not statistically significant (p 0.399). The Kaplan Meier estimated PFS was 77.5% in the SBRT arm and 72.5% in the SOC arm (p 0.88). The median BCTOS score for quality of life assessment was 82 (range, 60-96) in the SBRT arm and 79 (64-91) in the SOC arm (p 0.001).Conclusion:
Adding SBRT to standard of care systemic treatment in newly diagnosed patients with OMBC did not improve the response rate nor the progression free survival, however, better quality of life was observed in patients receiving SBRT