[Differences in Treatment Effect between Local and Distant Lesions in Breast Cancer Patients Administered Neoadjuvant...

We report different treatment effects between local and distant lesions based on oncotype DX in a patient with breast cancer administered neoadjuvant endocrine therapy. The patient was a 50-year-old woman. Ultrasound(US)showed a mass 16×11×11mm in diameter in the C area of her right breast. Histological examination revealed invasive ductal carcinoma positive for estrogen and progesterone receptor and negative for human epidermal growth factor receptor type 2(HER2), and a Ki-67 index of 38%. The recurrence score(RS)calculated from the core needle biopsy was 4(low-risk group)with a predicted 10-year risk of distant recurrence of 4% after 5 years of endocrine therapy. Oncotype DX showed that this patient would not benefit from chemotherapy. We administered neoadjuvant endocrine therapy. However, the tumor size increased to 26×18×15mm 1 month after treatment initiation. Therefore, right breast-conserving surgery and sentinel lymph node biopsy were performed. Histopathologically, the effect of the endocrine therapy was grade 0 and the surgical margins were negative. Even though RS was low in the breast, the effect of endocrine therapy differed between local and distant lesions such as circulating tumor cells.