[Two Cases of Node-Positive Breast Cancer in Which the Oncotype DX Test Was Performed but Yielded Inconclusive Results].

Oncotype DX is performed to predict prognosis and the added benefit of chemotherapy in hormone receptor-positive, HER2-negative breast cancer, with the goal of individualizing chemotherapy decisions. Here, we report 2 cases of early- stage hormone receptor-positive, HER2-negative breast cancer with lymph node metastases in which the oncotype DX test was performed but yielded inconclusive results. Case 1:A 53-year-old woman was diagnosed with left breast cancer following bloody nipple discharge. She underwent total mastectomy and axillary lymph node dissection. Two positive lymph nodes were identified;however, it was difficult to assess the invasive component of the primary tumor. When oncotype DX was performed, it was deemed inconclusive due to insufficient tumor tissue. Case 2:A 46-year-old woman was diagnosed with right breast cancer during routine follow-up at our department. She underwent total mastectomy and axillary lymph node dissection. Although the primary tumor was widely spread within the breast, assessment of the invasive component was challenging. Three lymph node metastases were identified. Oncotype DX was performed but was judged inconclusive due to insufficient tumor tissue.