PT3N0 triple-negative breast carcinosarcoma: surgery, EC chemotherapy, radiation, disease-free at 26 months

What happened, in summary

A 59-year-old woman developed a lump in the upper outer quadrant of her left breast in April 2022 and first underwent lumpectomy elsewhere. When she later presented for further care, the initial pathology was reviewed, and imaging of the breast, axilla, chest, abdomen, pelvis, and bone showed no residual local disease or distant metastasis. The tumor was reclassified as a rare grade 3 triple-negative breast carcinosarcoma with an endothelial component. Immunohistochemistry showed epithelial markers, including AE1/AE3 and CK7, together with endothelial markers CD34 and CD31; hormone receptors and HER2 were negative. Because of the metaplastic histology, she underwent revision breast-conserving surgery with axillary sampling. The completion surgery showed no remaining malignancy, and the cancer was staged pT3N0M0. She then received adjuvant chemotherapy with 4 cycles of epirubicin and cyclophosphamide every 3 weeks. Treatment was tolerated well, without grade 3 or higher toxicity. Radiation followed: 26 Gy in 5 daily fractions to the whole left breast using field-in-field IMRT, plus a 12.5 Gy tumor-bed boost in 5 daily fractions using an electron beam. Her only radiation side effect was faint skin redness. She was followed every 3 months at first and later every 6 months. Her December 2024 mammogram showed no suspicious changes, and in April 2025 she was clinically free of disease, 26 months after completing treatment. This care path preserved the breast while still addressing the aggressive biology of a rare metaplastic tumor. The absence of malignancy in the completion specimen, negative metastatic workup, and durable follow-up findings all supported a disease-free outcome after combined local and systemic treatment.