Abstract Background To date, no prospective randomized trials have been published to validate a curative-intent strategy combining standard-of-care systemic therapy (SOC ST) with local ablative treatment (LAT) in patients with oligometastatic breast cancer (OMBC). Available evidence derives solely from retrospective series. These series can sometimes be criticized for their short follow-up periods, the biological and anatomical heterogeneity of the patients’ tumors, the use of suboptimal or insufficiently detailed imaging modalities, and the non-consecutive nature of their recruitment. Our objective was to identify prognostic factors for progression-free survival (PFS) and overall survival (OS) in patients with HR+/HER2- OMBC. We specifically evaluated the impact of modern versus standard imaging techniques and the contribution of LAT. To minimize selection bias, we enrolled all eligible patients consecutively, and to ensure biological homogeneity we therefore restricted inclusion to the HR+/HER2- phenotype. Methods We retrospectively reviewed all patients consecutively diagnosed and treated from 2012 to 2020 at our institution for HR+/HER2-negative OMBC. OMBC was defined as breast cancer with 1 to 5 distant metastases. Cases were categorized as de novo or metachronous. Surrogate intrinsic subtype - Luminal A-like (Lum-A) and Luminal B-like (Lum-B) were defined according to St Gallen consensus criteria. Imaging were classified as modern imaging methods (MIMs: PET-CT or whole-body MRI) versus standard imaging methods (SIMs: bone scintigraphy or thoraco-abdomino-pelvic (TAP) CT). Number and location of metastases, treatments - SOC ST vs SOC ST plus LAT (surgery or SBRT) were collected. Survival analyses were performed using the Kaplan-Meier method, the Logrank test, and the Cox model including time-dependent variable. The use of time-dependent models allowed adjustment for the timing of LAT and helped mitigate immortal time bias. Results Median age was 57.0 years 29.0; 90.0; 23% patients had Lum-A and 77% had Lum-B tumors. OMBC was de novo in 34%, and metachronous in 65%. One organ was involved in 94% and 1 to 3 metastases in 88% cases. Metastatic sites included bone in 98 (68%), lymph node in 20 (14%), liver in 18 (12%), lung in 10 (7%), and brain in 7(5%) cases. MIMs were applied for staging in 54% of patients. No patients with four or five metastases received LAT (surgery or SBRT). Unfortunately, by lake of data, systemic treatment could not be analyzed. The median follow-up was 82.8 months. 73% relapsed and 51% died. Median OS was 81.1 months (95%CI 60.0-94.1). Median PFS was 26.5 months (95% CI 21.0-33.8). In univariable analysis, worse OS was associated with 4-5 metastases, liver metastases, Lum-B and SIMs (HR=2.56, 95% CI 1.58-4.13, p0.0001). LAT was associated with improved PFS (HR=0.34, 95% CI 0.20-0.58, p0.0001) and OS (HR=0.32, 95% CI 0.16-0.63, p=0.0009). In multivariable analysis: worse OS was associated with Lum-B, liver metastases and SIMs (HR=1.64, 95% CI 1.12-3.16, p=0.017). LAT improved PFS (HR=0.52, 95% CI 0.29-0.91, p=0.0233), showed a non-significant trend toward better OS (HR=0.52, 95% CI 0.25-1.08, p=0.078). In the subgroup staged with MIMs, in univariable analysis, LAT was significantly associated with improved PFS (HR=0.40, 95% CI 0.21-0.77, p=0.0064) and OS (HR = 0.29, 95% CI 0.12-0.73, p= 0.008). Conclusion This retrospective study reports prognostic data from a biologically homogeneous and unselected cohort of HR+/HER2- OMBC patients, with extended follow-up. In this study, LAT significantly improved PFS and showed a strong trend toward improved OS. In patients staged with MIMs, LAT was significantly associated with both PFS and OS, underscoring the importance of advanced imaging in selecting candidates for curative-intent strategies. Citation Format: J. Lacaze, F. Dalenc, E. De Maio, B. Cabarrou, T. Cassou Mounat, C. Massabeau, V. Nicolai, G. Selmes, E. Jouve, M. Ung, C. Korenbaum. Impact of modern imaging on survival in a retrospective and consecutive cohort of 145 HR+/HER2 negative oligometastatic breast cancer abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS1-10-15.
Lacaze et al. (Tue,) studied this question.