The Role of Combined Chemotherapy and Radiotherapy in Patients with TN0M0 Metaplastic Breast Cancer: a propensity score-matched analysis

Background: Metaplastic breast cancer (MBC) is rare cancer with a poor prognosis. The application of combined chemotherapy and radiotherapy (CCRP) to MBC is still controversial. The purpose of this study was to evaluate the efficacy of CCRP on MBC patients by propensity-score matching (PSM). 

Methods: Clinicopathological information of patients with MBC from surveillance, epidemiology, and end Results (SEER) database was obtained. Using log-rank test to compare the breast cancer-specific survival (BCSS) rates among groups and the Kaplan–Meier curve to show. Univariate and multivariate Cox proportional hazard models were conducted to assess BCSS. PSM was used to make 1:1 case-control matching.

Result：A total of 4672 patients diagnosed with MBC were extracted, our final sample included 2260 cases. A total of 602 (37.1%), 295 (18.2%), and 725 (44.7%) patients received non-therapy, only radiotherapy (RT), and CCRP, respectively. Age, tumor size, tumor grade, and surgery were independent indicators for BCSS. 28.4%, 31.3%, and 41.1% of patients received CCRP in stage T1, stage T2, and stage T3, respectively. However, for patients receiving BCS, only stage T2 and T3 MBC could benefit from CCRP. For patients receiving TM, only stage T3 MBC could benefit from CCRP. Multivariate analyses after PSM (n=490) confirmed that patients with N0M0 had more benefit from CCRP than RT. For patients receiving BCS, only stage T2 MBC could benefit from CCRP. However, for patients receiving TM, only stage T2 and T3 patients received CCRP were associated with better prognosis than patients received RT.

Conclusion: Per findings of the PSM analysis, CCRP might be a valid therapeutic strategy for MBC with TN0M0.