Long-Term Survival of a Patient with Triple-Negative Breast Cancer with Hormone Receptor Status Conversion between Primary and Metastatic Tumors

Patients with triple-negative breast cancer have poor survival after recurrence. However, previous studies have shown that receptor conversion can occur between primary breast tumor and metastatic sites. Herein, we describe the case of a 54- year-old woman with advanced breast cancer, which showed receptor conversion from primary tumor(triple-negative)to distant metastases(Luminal type). The patient had undergone left radical mastectomy and left axillary lymph node dissection at another hospital(pT3N0M0, Stage ⅡB, ER-negative, PgR-negative, and HER2-negative). She was referred to our hospital for adjuvant chemotherapy with 3 courses of 5-fluorouracil, epirubicin, and cyclophosphamide and 3 courses of docetaxel. Around 26 months after the surgery, the follow-up CT scan showed multiple lung nodules. Another 9 months later, her left axillary and mediastinal lymph nodes were enlarged. She received several courses of anticancer chemotherapy. After paclitaxel and bevacizumab were administered as seventh-line chemotherapy, a vacuum-assisted biopsy of the left axillary lymph node was performed to confirm the presence of metastasis. Furthermore, immunohistochemistry results showed that the metastatic tumor was ER-positive, PgR-positive, and HER2-negative. Fulvestrant and palbociclib were then initiated as first-line endocrine therapy. She has been stable for more than 18 months since. It is essential to perform biopsies of metastatic sites for optimal management of patients with metastatic breast cancer.