There is a lack of investigation into the biological characteristics and preoperative systemic therapy (PST) for occult breast cancer (OBC). For this study, departmental records in Breast Disease Center of Peking University First Hospital from January 2008 to December 2015 were retrospectively reviewed to identify cases of OBC. Eleven cases were included, and all patients were female, with a median age of 56 (range: 29−75) years. The sensitivity of magnetic resonance imaging (MRI) was 100%, and the false positive rate was 33.3%. Based on histologic analysis of the axillary node, 9 (81.8%) cases were grade 3, and 2 (18.2%) cases were grade 2; 4 (36.4%) cases were ≥10% estrogen receptor (ER) positive and 6 (54.5%) human epidermal growth receptor 2 (HER2) positive. Nine cases (81.8%) exhibited over 30% Ki67 expression. PST was performed in 5 of the 11 cases. The lymph node response rate was 100% (5/5), but no complete remission was achieved. In conclusion, aggressive subtypes were predominant among the included cases, and PST should be considered for OBC treatment options.

Keywords: Axillary presentation breast cancer; occult breast cancer (OBC); magnetic resonance imaging (MRI); preoperative systemic therapy (PST)