Is There a Correlation between Androgen Receptor (Ar) Expression in Er+ or Her2- Metastatic Breast Cancer and Response to Anti-Estrogen Treatment? A Pilot Study - Abstract
Background: There is recent interest in the use of antiandrogen therapy to treat metastatic androgen receptor positive (AR+) ‘triple negative’ metastatic breast cancer. Since AR testing is not routinely done, we conducted a pilot study to determine whether there was any evidence of a correlation between AR expression and response to antiestrogen treatment in estrogen receptor positive (ER+) metastatic breast cancer
(MBC) patients. Such a correlation might identify ER+ MBC patients who are candidates for AR testing and a trial of antiandrogen therapy for AR+ tumors.
Methods: A retrospective study was conducted of 46 randomly selected patients treated with anti-estrogen therapy for ER+ Her2-ve MBC who had an available tumor biopsy. Immunohistochemical assessment of AR expression was performed on all available primary and metastatic tumor specimens for each patient. Patients were classified into two categories according to their total duration of clinical benefit from anti-estrogen treatment: A) ? 6 months (m) and B) <6 m.
Results: AR was +ve in all 20 primary tumor samples available and in 85% (40/47) of the metastatic lesions. There were 39 (85%) and 7 (15%) patients in endocrine response categories A and B respectively. No statistically significant differences were found between the presence and intensity of AR staining in the metastases and the duration of benefit from hormone therapy.
Conclusion: Our results do not suggest that response to anti-estrogen treatment can determine possible candidates for AR testing and a trial of anti-androgen therapy for ER+ AR+ HER2- patients. A significant minority of metastases from ER+ AR+ primary tumours become AR-.