Clinical verification of sensitivity to preoperative chemotherapy in cases of androgen receptor-expressing positive breast cancer

Background: Triple-negative breast cancer (TNBC) patients testing positive for androgen receptor (AR) expression are thought to be chemotherapy resistant, similar to other hormone receptor-positive breast cancers; however, this has not been substantially validated in the clinic. In this study, we investigated the association between chemotherapy sensitivity and AR expression in patients treated with neoadjuvant chemotherapy (NAC) using standardised chemotherapy criteria and regimens. Methods: A total of 177 patients with resectable early-stage breast cancer were treated with NAC. Oestrogen receptor, progesterone receptor, HER2, Ki67 and AR status were assessed immunohistochemically. Results: Sixty-one patients were diagnosed with TNBC; AR expression was identified in 23 (37.7%), which was significantly less common than that found in non-TNBC patients (103 of 116; 88.8%; P<0.001). The rate of pathological complete response after NAC was significantly lower (P - 0.001), and disease recurrence was more common (P - 0.008) in patients with AR-positive compared with those with AR-negative TNBC. In TNBC cases, as expected, the non-recurrence period in cases that were negative for AR expression was significantly extended (P - 0.006, log-rank). Conclusions: Androgen receptor expressions may be useful as biomarkers to predict treatment responses to NAC in TNBC. Moreover, induction of a change in subtype to the AR-negative phenotype was observed after NAC.