Abstract
Introduction
Triple-negative breast cancer (TNBC) is a heterogeneous subtype of breast cancer with the worst outcome, is not amenable for known target therapies, and has a poor response to chemotherapy. Androgen receptor (AR) was evaluated as a predictive, prognostic, and therapeutic factor in TNBC, but with contradicting results and the cutoff used for positive was also varied among studies. Thus, we studied 104 Indian women with TNBC for proportion showing AR expression and responses and survival outcomes compared over a period of 60 months with standard of care.
Objectives
Primary: To observe the proportion of AR expression in TNBC. Secondary: To compare (1) pathological response to neoadjuvant chemotherapy (NACT) and (2) overall survival (OS) of both groups.
Materials and Methods
This is a prospective descriptive study of 104 female patients with TNBC who visited the medical oncology department at a tertiary hospital in South India over a period of 2 years (June 2018–June 2020). They were diagnosed with TNBC by Immunohistochemistry (IHC); hence, they tested negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2) receptors. Patients with HER2 2+ IHC were confirmed negative by fluorescence in situ hybridization testing. They were analyzed with IHC for AR expression using EP140 rabbit monoclonal primary antibody interpreted by a single breast pathologist, and proportion of TNBC expressing AR were identified with a cutoff > 10% nuclear expression. They were managed as per the standard of care necessary for a particular stage. Results were analyzed comparing the baseline characteristic, treatment response, recurrence rate, and survival outcomes over a follow-up period of 60 months.
Results
Percentage of AR expression in TNBC in this study was 35%. Twenty-five percent patients (28/104) were treated with NACT and complete pathological response was seen in 1/13 (7.69%) versus 7/22 (31.8%) in AR-positive compared with AR negative group (p 0.003). The AR-positive group showed significant survival advantage compared with the AR-negative group. Median OS of AR-negative group was reached at 29 months whereas for the AR-positive group it was 49 months (p = 0.58). The AR-positive group showed late recurrences after 24 months in follow-up.
Conclusion
This study showed that the proportion of TNBCs showing AR expression was much higher. Assessment of AR status in patients with TNBC provides additional information on prognosis and also predicts response to chemotherapy. AR-positive TNBC represents a breast cancer subtype with unique features with potential targeted therapies.
Keywords
TNBC - AR - 5-year-follow-up - IHC - prognosis - response - pCR
