Abstract: Breast cancer is the most common female malignant neoplasm in Poland and around the world. Precise determination of tumor molecular profile allows application of appropriate anticancer therapy, increasing the chances of recovery. A 28-year-old woman detected a thickening in her left breast. Mammography showed a change measuring 60 mm (radiologically BIRADS 5). The biopsy revealed invasive ductal carcinoma, luminal subtype B, HER2 positive (cT3N1M0). Neoadjuvant chemotherapy was administered and then breast conserving surgery was performed. In postoperative histopathology cancer, biological subtype was evaluated: HER2 positive, nonluminal (ypT2ypN0cM0). Then, postoperative radiotherapy was performed. After 14 months, breast ultrasonography (US) and mammography (MGF) revealed the presence of suspicious changes (BIRADS 4). Tru-cut biopsy confirmed cancer recurrence (luminal subtype B, HER2 negative, ER negative, PgR: 10%, Ki-67: 70%). Despite implemented and modified chemotherapy regimens, local progression occurred. Genetic testing excluded BRCA  gene mutation. The patient qualified for radical mastectomy modo Halsted (ypT4bN0cM0). Postoperative microscopic examination revealed triple negative breast invasive carcinoma of no special type. After 22 months, metastatic lesions in lungs and left retrosternal nodes appeared. Due to the limited possibilities of systemic treatment, the patient qualified for stereotactic radiotherapy of tumors in the lungs’ and left retrosternal nodes. Advancement, histological type and molecular profile should be controlled at each stage of the disease, as they may change several times and require modification of therapy.
Keywords: biological subtype, phase disease, personalized treatment