Abstract
PurposeDue to the rarity of metaplastic breast carcinoma (MpBC), no randomized trials have investigated the role of combined chemotherapy and radiotherapy (CCRP) in this condition. We aimed to explore and identify the effectiveness of CCRP in patients with regional lymph node metastasis (N+) non-metastatic MpBC.Materials and MethodsData were obtained from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program database. We assessed the effects of CCRP on overall survival (OS), breast cancer-specific survival (BCSS), and breast cancer-specific death (BCSD) using Kaplan-Meier analysis, competing risk model analysis, and competing risk regression mode analysis.ResultsA total of 707 women and 361 death cases were included in the unmatched cohort, of which 76.45% (276/361) were BCSD, and 23.55% (85/361) were non-breast cancer-specific deaths (non-BCSD). Both the ChemT and CCRP groups had better OS (ChemT group: HR: 0.59, 95% CI: 0.45–0.78, P<0.001; CCRP group: HR: 0.31, 95% CI: 0.23–0.41, P<0.001) and BCSS (ChemT group: HR: 0.63, 95% CI: 0.45–0.87, P<0.001; CCRP group: HR: 0.32, 95%CI: 0.22–0.46, P<0.001) than the non-therapy group. Subjects in the CCRP group tended to have significantly lower cumulative BCSD (Gray’s test, P=0.001) and non-BCSD (Gray’s test, P<0.001) than the non-therapy group or ChemT group. In competing risk regression model analysis, subjects in the CCRP group had a better prognosis in BCSD (HR: 0.710, 95% CI: 0.508–0.993, P=0.045) rather than the ChemT group (HR: 1.081, 95% CI: 0.761–1.535, P=0.660) than the non-therapy group.ConclusionOur study demonstrated that CCRP could significantly decrease the risk of death for both BCSD and non-BCSD and provided a valid therapeutic strategy for patients with N+ non-metastatic MpBC.
Highlights
Metaplastic breast carcinoma (MpBC), characterized by the coexistence of carcinoma with non-epithelial cellular elements, is a rare primary breast malignancy
Of the 707 subjects included from our study cohort, 337 received CCRP, 218 received chemotherapy alone, and 152 received neither CCRP or chemotherapy
We found that CCRP, not ChemT, could significantly decrease the risk of breast cancer-specific death (BCSD) and non-BCSD for patients with N+ MpBC
Summary
Metaplastic breast carcinoma (MpBC), characterized by the coexistence of carcinoma with non-epithelial cellular elements, is a rare primary breast malignancy. More clinical evidence for treatment strategies were needed for MpBC patients since current guidelines were written based on IDC [1, 10]. Multimodality treatment, or combined chemotherapy and radiotherapy (CCRP), is the standard treatment for breast carcinoma due to HR- tumors in patients with MpBC. Few well-performed studies have been conducted on the efficacy of CCRP in patients with resectable MpBC. For these reasons, more studies are urgently needed to confirm the real-world curative effect of CCRP in patients with MpBC, especially those with regional lymph nodes metastasis (N+), who always have a worse prognosis than those with no metastasis of regional lymph nodes (N0) [13]
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