Survival Outcomes for Metaplastic Breast Cancer Differ by Histologic Subtype

Area of Science:

• Oncology
• Pathology

Background:

• Metaplastic breast carcinoma (MBC) is a rare and aggressive breast cancer subtype.
• MBC is associated with poorer survival compared to other triple-negative breast cancers.

Purpose of the Study:

• To compare survival outcomes of MBC histologic subtypes.
• To compare survival outcomes of MBC with non-metaplastic triple-negative breast cancer.

Main Methods:

• Clinicopathologic and treatment data were collected for MBC and triple-negative breast cancer patients from 1995-2017.
• MBC tumors were classified by histology: squamous, spindle, heterologous mesenchymal, or mixed.
• Kaplan-Meier method was used for survival outcome comparisons.

Main Results:

• Heterologous mesenchymal MBC showed the best 5-year survival (88% BCSS), while squamous MBC had the worst (56% BCSS).
• MBC patients had significantly worse overall survival, breast cancer-specific survival (BCSS), and recurrence-free survival compared to non-MBC triple-negative breast cancer patients (HR 2.4, p<0.001).
• Among 10 MBC patients receiving neoadjuvant chemotherapy, 4 progressed and 3 had no response.

Conclusions:

• Metaplastic breast carcinoma is linked to inferior survival rates compared to other triple-negative breast cancers.
• Survival varies significantly among MBC subtypes, with heterologous mesenchymal being the most favorable and squamous the least.
• Further research is needed to develop targeted therapies for MBC's distinct biological characteristics.