Aims Triple-negative breast cancer comprises different histological subtypes, including metaplastic breast cancer (MBC) and ductal carcinomas (IDCs). The purpose of this study was to compare triple-negative MBC (TN-MBC) with triple-negative IDC (TN-IDC) in terms of survival and predictive factors.
Methods With access to the Surveillance, Epidemiology and End Result (SEER) database, a total of 19 383 patients met the eligibility criteria. Clinicopathological characteristics were compared between groups using the χ2 test. Univariate and multivariate analyses were applied to evaluate the disease-specific survival (DSS) and overall survival (OS). Subgroup analyses summarised the hazard ratios of TN-MBC versus TN-IDC using a forest plot.
Results A total of 586 patients with TN-MBC and 18 797 with TN-IDC were included in this study. Patients with TN-MBC were older and presented with larger tumour sizes, relatively rare lymph node positive disease, and had received more chemotherapy. Compared with TN-IDC, the TN-MBC group showed a significantly poorer prognosis before and after the 1:3 matched case-control analysis. Further subgroup analysis indicated that patients with TN-MBC were older, were from specific races, and those with distant metastasis and not receiving radiotherapy had worse prognosis than patients with TN-IDC in terms of DFS and OS.
Conclusion Our results showed that patients with TN-MBC had unique clinicopathological characteristics and poorer prognostic subtype compared with TN-IDC. This improves our understanding of the clinicopathological and prognostic features of this rare entity but also provides more convincing therapeutic guidelines for TN-MBC in patients with breast cancer.
- triple negative breast cancer
- metaplastic carcinoma
- invasive ductal carcinoma
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YL and NZ contributed equally.
Handling editor Cheok Soon Lee.
Contributors QY designed the article. YL analysed the data. NZ wrote the paper. HZ wrote the paper and tables.
Funding This work was supported by the National Natural Science Foundation of China (No.81272903; No.81672613), Key Research and Development Program of Shandong Province (No.2016GGE2775), Shandong Science and Technology Development Plan (2016CYJS01A02) and Special Support Plan for National High Level Talents (“Ten Thousand Talents Program”) to Qifeng Yang. And the National Natural Science Foundation of China (No. 81502285) and China Postdoctoral Science Foundation to Ning Zhang.
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.