Abstract PS4-11-14: Anthracycline-based Systemic Chemotherapy on Long-term Prognosis of Metaplastic Breast Cancer: A Real World Study with 637 Cases in 14 multi-center

Abstract Background: The standard chemotherapy treatment regimen for metaplastic breast cancer (MpBC) remained uncertain. This study aimed to assess the survival disparities between anthracycline-based and non-anthracycline-based regimens and investigate appropriate chemo-regimen for MpBC patients in real world. Patients and Methods: A total of 637 cases with MpBC in admitting diagnosis between 2002 and 2025 were collected from 14 large hospitals in China. Kaplan- Meier analysis, univariate and multivariate Cox proportion hazard models, and cumulative incidence flow were performed to estimate survival effect and identify prognostic factors comprehensively during the median follow-up time of 30 months. Results: Among the 373 patients enrolled in final study, totally 243 (65.1%) patients received anthracycline-based regimen (anthracycline cohort) whereas 130 (34.9%) patients with non-anthracycline-based regimen (non-anthracycline cohort). Subjects in anthracycline cohort had an absolute improvement of 13.6% (89.4% vs. 75.8%) and 7.5% (82.9% vs. 75.9%) in 10-year overall survival (OS) and 10-year local-regional recurrence free survival (LRFS), respectively, in comparison with those in non-anthracycline cohort. And anthracycline-based regimen was found to be an independently favorable factor of OS through multivariate Cox analysis. The local-regional recurrence occurred in 6.2% (23/373) of patients, while 13.1% (49/373) of MpBC patients developed distant metastases. Conclusion: This multi-center study identified the association between administration of anthracycline and improved OS, anthracycline-based regimen had higher likelihood to be the preferred protocol for MpBC. Citation Format: C. Zhou, P. Ni, Z. Dai, G. Qiao, Y. Ren. Anthracycline-based Systemic Chemotherapy on Long-term Prognosis of Metaplastic Breast Cancer: A Real World Study with 637 Cases in 14 multi-center [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 PS4-11-14.