Androgen Receptor Expression in Endometrial Carcinoma:

Androgen receptor and its correlation with estrogen and progesterone receptors, aimed for identification of cases for future anti-androgen therapy in endometrial cancers

INTRODUCTION

The expression of androgen receptor (AR) is not commonly tested or studied in uterine cancers, unlike estrogen receptor (ER) and progesterone receptor (PR) which are positive in most endometrial carcinomas. In this series, we evaluated the expression of AR and its comparison to ER and PR in different types of endometrial cancers and have reviewed the literature.

MATERIALS AND METHODS

The status of AR, ER, and PR expression were evaluated in 71 cases which were categorized into endometrial endometrioid cancer (EEC), non-endometrioid endometrial cancers (NEEC), and metastatic carcinomas of endometrium. Expression of the receptors were compared to each other as well as to mismatch repair proteins (MMR), p53, and body mass index (BMI) using Fisher's Exact test in the StatPlus software.

RESULTS

In EECs, the positivity was 97% for all the three receptors. In NEEC, positivity rates were 68%, 48%, and 35% for AR, ER, and PR respectively. In Metastatic carcinomas, AR and ER positivity was seen in 100% while PR was positive in 75% of the cases. In all cancers, the rates were 17% (11/66) for MMR loss, 57% (30/53) for p53 aberrant expression, and 76% (54/71) for the patients with BMI of ≥ 25 (kg/m2).

CONCLUSION

AR is expressed in a high percentage of endometrial cancers. Its significance is more evident in high-grade NEEC where ER and PR may not be expressed. These findings warrant further evaluation of AR expression and candidacy of this pathway as a potential therapeutic target in endometrial cancers.

Stranger Things: New Roles and Opportunities for Androgen Receptor in Oncology Beyond Prostate Cancer

The androgen receptor (AR) is one of the oldest therapeutic targets in oncology and continues to dominate the treatment landscape for advanced prostate cancer, where nearly all treatment regimens include some form of AR modulation. In this regard, AR remains the central driver of prostate cancer cell biology. Emerging preclinical and clinical data implicate key roles for AR in additional cancer types, thereby expanding the importance of this drug target beyond prostate cancer. In this mini-review, new roles for AR in other cancer types are discussed as well as their potential for treatment with AR-targeted agents. Our understanding of these additional functions for AR in oncology expand this receptor's potential as a therapeutic target and will help guide the development of new treatment approaches.

Androgens in endometrial carcinoma: the killer or helper?

PURPOSE

The aim of this review is to discuss the role of androgens in the progression of endometrial carcinoma (EC) with particular focus on the different kinds of androgenic hormones, androgen receptor (AR) and intracrine androgen metabolism.

METHODS

A comprehensive literature search within PubMed was performed. Selected publications related to androgens and EC were reviewed.

RESULTS

There are different kinds of androgenic hormones, and different kinds of androgens may have different effects. Elevated androgens (especially testosterone) have been associated with an increased EC risk in postmenopausal women. 5α-reductases (5α-Reds) and 17β-hydroxysteroid dehydrogenase type 2 (17βHSD2) pathway may inhibit the progression of EC mediated by dihydrotestosterone (DHT), but aromatases stimulate further progression of EC. The most of studies accessing the prognostic value of AR have found that AR expression may be a favorable prognostic indicator.

CONCLUSION

Androgens may have both oncogenic and tumor suppressive roles. Androgen-specific biases in metabolism and the expression of AR may contribute to the different prognosis of patients with EC.

What Role do Androgens Play in Endometrial Cancer?

The role of estrogens and progesterone in the development and progression of endometrial cancer is well-established, but there are very little data about the role of androgens. There are five different androgens produced in women: dehydroepiandrosterone sulphate (DHEAS), dehydroepiandrosterone (DHEA), androstenedione (A₄), testosterone (T) and dihydrotestosterone (DHT). The most potent hormones are T and DHT, the latter being mainly produced from T in peripheral tissues, including endometrium. Although they are considered to exert antiproliferative effects in many settings and the expression of their receptors is more often associated with a good prognosis in EC, it is still unknown in which specific settings androgens have carcinogenic or protective effects in EC.

Androgen Signaling in Uterine Diseases: New Insights and New Targets

Common uterine diseases include endometriosis, uterine fibroids, endometrial polyps, endometrial hyperplasia, endometrial cancer, and endometrial dysfunction causing infertility. Patients with uterine diseases often suffer from abdominal pain, menorrhagia, infertility and other symptoms, which seriously impair their health and disturb their lives. Androgens play important roles in the normal physiological functions of the uterus and pathological progress of uterine diseases. Androgens in women are synthesized in the ovaries and adrenal glands. The action of androgens in the uterus is mainly mediated by its ligand androgen receptor (AR) that regulates transcription of the target genes. However, much less is known about the signaling pathways through which androgen functions in uterine diseases, and contradictory findings have been reported. This review summarizes and discusses the progress of research on androgens and the involvement of AR in uterine diseases. Future studies should focus on developing new therapeutic strategies that precisely target specific AR and their related signaling pathways in uterine diseases.

Molecular Regulation of Androgen Receptors in Major Female Reproductive System Cancers

There are three main types of cancer in the female reproductive system, specifically ovarian cancer (OVCA), endometrial cancer (EC), and cervical cancer (CC). They are common malignant tumors in women worldwide, with high morbidity and mortality. In recent years, androgen receptors (ARs) have been found to be closely related to the occurrence, progression, prognosis, and drug resistance of these three types of tumors. This paper summarizes current views on the role of AR in female reproductive system cancer, the associations between female reproductive system cancers and AR expression and polymorphisms. AR regulates the downstream target genes transcriptional activity and the expression via interacting with coactivators/corepressors and upstream/downstream regulators and through the gene transcription mechanism of “classical A/AR signaling” or “non-classical AR signaling”, involving a large number of regulatory factors and signaling pathways. ARs take part in the processes of cancer cell proliferation, migration/invasion, cancer cell stemness, and chemotherapeutic drug resistance. These findings suggest that the AR and related regulators could target the treatment of female reproductive system cancer.

The Clinicopathological Significance and Prognostic Value of Androgen Receptor in Endometrial Carcinoma: A Meta-Analysis

Background

The role of androgen receptor (AR) in evaluating the prognosis of patients with endometrial cancer (EC) remains controversial. Here, we performed a meta-analysis to assess whether AR expression improves EC survival outcomes.

Methods

We searched related articles published before August 2021 in PubMed, EMBASE, and Web of Science. The association between AR expression and patient prognosis was estimated with hazard ratios (HRs) and odds ratios (ORs) with their corresponding 95% confidence intervals (95% CIs). The review is registered on PROSPERO, registration number: CRD42021268591.

Results

Ten studies including 1,485 patients were enrolled in the meta-analysis. The results showed that AR expression in EC tissues was associated with a better survival in crude analyses (HR = 1.63, 95% CI = 1.32–2.02, P < 0.001). However, no significant relation was found after the adjustment of the confounding factors (HR = 1.68, 95% CI = 0.75–3.75, P = 0.205). In subgroup analyses, grade 1–2 disease, stage I–II disease, negative lymph node status, and lack of the lymphovascular invasion were more common in AR-positive groups (OR = 0.47, 0.48, 0.37, and 0.57; 95% CI = 0.45–0.62, 0.35–0.65, 0.24–0.56, and 0.37–0.89). Furthermore, AR expression was more common in endometrioid cancers (OR = 2.39, 95% CI = 1.79–3.20).

Conclusions

AR expression is significantly associated favorable characteristics including low-grade disease, early-stage disease, negative lymph node status, and lack of the lymphovascular invasion and a specific histology—endometrioid cancer. However, AR is not an independent prognostic factor.

Differential Expression of Steroid Hormone Receptors and Ten Eleven Translocation Proteins in Endometrial Cancer Cells

Steroid hormones govern the complex, cyclic changes of the endometrium, predominantly through their receptors. An interplay between steroid hormones and epigenetic mechanisms controls the dynamic endometrial gene regulation. Abnormalities in expression of genes and enzymes associated with steroid hormone signaling, contribute to a disturbed hormonal equilibrium. Limited evidence suggests the involvement of TET (Ten Eleven Translocation)-mediated DNA hydroxymethylation in endometrial cancer, with some data on the use of TET1 as a potential prognostic and diagnostic biomarker, however the mechanisms guiding it and its regulation remains unexplored. This study aims to explore the changes in the expressions of TETs and steroid hormone receptors in response to estrogen and progesterone in endometrial cancer cells. Gene expression was examined using real-time PCR and protein expression was quantified using fluorescent western blotting in endometrial cancer cell lines (AN3 and RL95-2). Results indicate that TET1 and TET3 gene and protein expression was cell-specific in cancer cell-lines. Protein expression of TET1 was downregulated in AN3 cells, while TET1 and TET3 expressions were both upregulated in RL95-2 cells in response to estrogen-progesterone. Further, a decreased AR expression in AN3 cells and an increased ERα and ERβ protein expressions in RL95-2 cells was seen in response to estrogen-progesterone. PR gene and protein expression was absent from both cancer cell-lines. Overall, results imply that expressions of steroid hormones, steroid-hormone receptors and TETs are co-regulated in endometrial cancer-cells. Further studies are needed to interpret how these mechanisms fit in with DNMTs and DNA methylation in regulating endometrial biology. Understanding the role of TETs and hydroxymethylation in steroid hormone receptor regulation is crucial to comprehend how these mechanisms work together in a broader context of epigenetics in the endometrium and its pathologies.

Androgen Receptor Immunohistochemical Expression in Undifferentiated/Dedifferentiated Endometrial Carcinoma

Uterine undifferentiated (UC)/dedifferentiated (DEAC) carcinomas are rare malignant neoplasms. They tend to pursue an aggressive clinical course with an advanced stage at presentation. It has been found that androgen receptor (AR) might play a role as a prognostic and therapeutic marker in endometrial carcinoma. However, its expression in UC/DEAC has not been investigated. Herein, the aim of this study was to evaluate the expression of AR along with estrogen receptor (ER), progestin receptor (PR), and HER2 in UC/DEAC and also in other subtypes of high-grade endometrial carcinomas. Review of our pathology database over the period of 2011 to 2019 identified 16 UC/DEAC cases (N=16). We also randomly selected other high-grade endometrial carcinomas including FIGO 3 endometrioid carcinoma (N=9), serous carcinoma (N=8), clear cell carcinoma (N=12) and carcinosarcoma (N=10) for comparison. Immunohistochemical stains for AR, ER, PR, and HER2 were performed on all 55 cases. The protein expression was evaluated both quantitatively and qualitatively. In DEAC cases both the undifferentiated component and the well-differentiated component were recorded separately. Overall, variable degrees of AR reactivity (by Allred scoring method) was present in 63% of UC/DEACs(10/16), 67% of FIGO 3 endometrioid carcinomas (6/9), 88% of serous carcinomas (7/8), 80% of carcinosarcomas (8/10), and 9% of clear cell carcinoma (1/12). AR expression was most often seen with PR (70%) or ER (60%) staining in UC/DEACs. Thirteen cases of UC/DEACs were positive for at least 1 hormone receptor. HER2 was negative in all UC/DEACs. Almost all other high-grade carcinoma cases were negative for HER2 except 20% of carcinosarcoma (2/10) and 13% of serous carcinoma (1/8) which showed 3+ HER2. Loss of AR appears to be associated with worse clinicopathologic parameters in UC/DEAC. AR is highly expressed in UC/DEAC, and in the majority of FIGO 3 endometrioid carcinomas, serous carcinomas, and carcinosarcoma. These findings suggest a potential role for androgen inhibitors in the management of patients with these tumors.

Differential Expression of Androgen Receptor in Type I and Type II Endometrial Carcinomas: A Clinicopathological Analysis and Correlation with Outcome

Objectives

Endometrial carcinomas (EC) are the most common gynecological malignancies and are conventionally divided into type I and type II due to diagnostic and prognostic considerations. Female hormone expression in EC is extensively studied; however, data about androgen receptor (AR) expression in EC are sparse. We aimed to study AR expression in different types of EC at our institute and whether it had an impact on patient outcomes.

Methods

A retrospective analysis of EC cases diagnosed and treated from 2010–2019. AR immunohistochemical expression was tested in 52 EC cases (type I = 40; type II = 12). Histological typing was verified according to conventional diagnostic criteria. Only primary EC were included without neoadjuvant therapy. Histologic score was calculated as: stain intensity (graded 0–3) × positive cells percentage (graded 0–4). Level of expression was scored from 0 to 12.

Results

The mean age of the selected patients was 60.3 years (range = 31–88 ± 12.6). Recurrence was detected in 11 (21.2%) patients. The outcome was 40 patients were alive without disease, eight alive with disease, three dead of disease, and one dead of other causes. About 62.5% of type I-EC and 25.0% of type II-EC were AR positive. AR expression was analyzed against different clinicopathological parameters including: type (p = 0.005), histotype (p = 0.044); grade (p = 0.035); age group (p = 0.207); menopause (p = 0.086); estrogen receptor (ER) expression (p = 0.284); atypical complex hyperplasia (p = 0.594); tumor stage (p = 0.994); tumor recurrence (p = 0.530); node status (p = 0.110); and outcome (p = 0.202).

Conclusion

AR expression was higher in type I EC, endometrial endometrioid carcinoma histotype, and with a lower grade. AR expression was not significantly correlated with age, stage, ER, atypical hyperplasia, recurrence, node status, or outcome. Results agree with recent literature that AR expression is associated with better-differentiated EC and may be a potential hormonal therapeutic tool.

Androgen and Estrogen Receptor Expression in Different Types of Perianal Gland Tumors in Male Dogs

Perianal gland tumors are modified sebaceous glands present in the skin of the perianal region in the dog. Hormonal stimulation may induce hyperplasia of the perianal glands or their neoplastic progression. The presence of androgen (AR) and estrogen (ER) receptors have been demonstrated both in normal perianal glands as well as in perianal tumors. The aim of the study was an immunohistochemical assessment of the expression of estrogen and androgen receptors in perianal gland tumors in dogs as an applicatory marker for antihormonal treatment. Biopsy samples of perianal masses were collected from 41 male dogs. A histopathological examination revealed 24 adenomas, 12 epitheliomas and five carcinomas. The immunohistochemical staining showed a mainly nuclear expression of AR and ER in the neoplastic cells. Both the androgen and estrogen receptors were expressed in adenoma, epithelioma and carcinoma cases; however, the highest expression of the receptors was stated in the adenoma and epithelioma. In the case of the carcinoma, the expression of sex hormone receptors was very weak. The differences of the number of cells expressing AR and ER as well as the observed differentiated intensity of staining in the studies demonstrated that the determination of the expression of the sex hormone receptors may be useful to elaborate a diagnostic and therapeutic algorithm.

Identification of a novel subgroup of endometrial cancer patients with loss of thyroid hormone receptor beta expression and improved survival

BACKGROUND

Endometrial cancer (EC) is the most common gynecologic cancer in women, and the incidence of EC has increased by about 1% per year in the U. S over the last 10 years. Although 5-year survival rates for early-stage EC are around 80%, certain subtypes of EC that lose nuclear hormone receptor (NHR) expression are associated with poor survival rates. For example, estrogen receptor (ER)-negative EC typically harbors a worse prognosis compared to ER-positive EC. The molecular basis for the loss of NHR expression in endometrial tumors and its contribution to poor survival is largely unknown. Furthermore, there are no tools to systematically identify tumors that lose NHR mRNA expression relative to normal tissue. The development of such an approach could identify sets of NHR-based biomarkers for classifying patients into subgroups with poor survival outcomes.

METHODS

Here, a new computational method, termed receptLoss, was developed for identifying NHR expression loss in endometrial cancer relative to adjacent normal tissue. When applied to gene expression data from The Cancer Genome Atlas (TCGA), receptLoss identified 6 NHRs that were highly expressed in normal tissue and exhibited expression loss in a subset of endometrial tumors.

RESULTS

Three of the six identified NHRs - estrogen, progesterone, and androgen receptors - that are known to lose expression in ECs were correctly identified by receptLoss. Additionally, a novel association was found between thyroid hormone receptor beta (THRB) expression loss, increased expression of miRNA-146a, and increased rates of 5-year survival in the EC TCGA patient cohort. THRB expression loss occurs independently of estrogen and progesterone expression loss, suggesting the discovery of a distinct, clinically-relevant molecular subgroup.

CONCLUSION

ReceptLoss is a novel, open-source software tool to systematically identify NHR expression loss in cancer. The application of receptLoss to endometrial cancer gene expression data identified THRB, a previously undescribed biomarker of survival in endometrial cancer. Applying receptLoss to expression data from additional cancer types could lead to the development of biomarkers of disease progression for patients with any other tumor type. ReceptLoss can be applied to expression data from additional cancer types with the goal of identifying biomarkers of differential survival.

Evaluating the efficacy of enzalutamide and the development of resistance in a preclinical mouse model of type-I endometrial carcinoma

Androgen Receptor (AR) signaling is a critical driver of hormone-dependent prostate cancer and has also been proposed to have biological activity in female hormone-dependent cancers, including type I endometrial carcinoma (EMC). In this study, we evaluated the preclinical efficacy of a third-generation AR antagonist, enzalutamide, in a genetic mouse model of EMC, Sprr2f-Cre;Pten^fl/fl. In this model, ablation of Pten in the uterine epithelium leads to localized and distant malignant disease as observed in human EMC. We hypothesized that administering enzalutamide through the diet would temporarily decrease the incidence of invasive and metastatic carcinoma, while prolonged administration would result in development of resistance and loss of efficacy. Short-term treatment with enzalutamide reduced overall tumor burden through increased apoptosis but failed to prevent progression of invasive and metastatic disease. These results suggest that AR signaling may have biphasic, oncogenic and tumor suppressive roles in EMC that are dependent on disease stage. Enzalutamide treatment increased Progesterone Receptor (PR) expression within both stromal and tumor cell compartments. Prolonged administration of enzalutamide decreased apoptosis, increased tumor burden and resulted in the clonal expansion of tumor cells expressing high levels of p53 protein, suggestive of acquired Trp53 mutations. In conclusion, we show that enzalutamide induces apoptosis in EMC but has limited efficacy overall as a single agent. Induction of PR, a negative regulator of endometrial proliferation, suggests that adding progestin therapy to enzalutamide administration may further decrease tumor burden and result in a prolonged response.

The androgen receptor expression and association with patient's survival in different cancers

To understand the androgen receptor (AR) in different human malignancies, we conducted a pan-cancer analysis of AR in different tumor tissues and association with patient survival and obtained AR expression data from The Cancer Genome Atlas. Pan-Cancer Analysis of AR indicated that 12 tumor types had decreased AR expression in the tumor, while glioblastoma multiforme has overexpressed AR. The survival analysis showed that high AR mRNA is associated with poor survival of stomach adenocarcinoma and low-grade glioma, but better survival of adrenocortical carcinoma, kidney renal clear cell carcinoma, acute myeloid leukemia, liver hepatocellular carcinoma, ovarian serous cystadenocarcinoma, and skin cutaneous melanoma based on AR mRNA, protein or AR-score. AR was associated with different clinical characteristics and AR correlated genes enriched in cancer-related pathways. These data indicate that AR signaling may be strongly associated with some cancer development and patients' survival, which is promising for potential treatment using antiandrogen therapies.

Emerging biomarkers in ovarian granulosa cell tumors

OBJECTIVE

Although the majority of ovarian granulosa cell tumors can be successfully managed with surgery, a subset require chemotherapy for residual and recurrent disease. The benefit of chemotherapy in this population, however, remains controversial. There is therefore interest in the development of more tolerable and effective treatment options for advanced ovarian granulosa cell tumors. We report the use of immunohistochemistry to investigate how biomarkers could inform clinical trials in granulosa cell tumors with an emphasis on emerging androgen antagonistic, immunotherapeutic, and anti-angiogenic approaches.

METHODS

Immunohistochemistry for androgen receptor, the immune markers programmed cell death ligand 1, indoleamine-2,3 dioxygenase, and cluster of differentiation 8, and the vascular marker cluster of differentiation 31 were evaluated on formalin-fixed paraffin-embedded whole tissue sections from 29 cases of adult-type granulosa cell tumors. Results were evaluated with clinicopathologic variables including recurrence.

RESULTS

59% of granulosa cell tumors were androgen receptor-positive, suggesting a potential role for anti-androgen therapy in this tumor type. In contrast, the targetable immune modulatory molecules programmed cell death ligand 1 and indoleamine-2,3 dioxygenase were scarcely expressed, with no cases showing tumorous programmed cell death ligand 1 and a single case demonstrating very focal tumorous indoleamine-2,3 dioxygenase staining. A minority of cases expressed programmed cell death ligand 1 in occasional tumor-associated macrophages and indoleamine-2,3 dioxygenase in peritumoral vessels. Tumor-infiltrating cytotoxic T cells were also scarce in granulosa cell tumors, arguing against a significant role for immunotherapy in the absence of additional immunostimulation. Cluster of differentiation 31 immunostaining revealed a range of vascular densities across granulosa cell tumors, and future studies evaluating the role of vascular density as a predictor of response to angiogenesis inhibition are warranted. None of the biomarkers investigated were significantly correlated with recurrence, and the only clinicopathologic feature significantly correlated with outcome was stage at presentation.

CONCLUSIONS

Biomarker data suggest that many ovarian granulosa cell tumors could be candidates for anti-androgen therapy, while the potential role for immunotherapy appears more limited. Vascular density could be useful for identifying optimal candidates for angiogenesis inhibition. Incorporation of these biomarkers into clinical trials could help optimize patient selection.

Strong androgen receptor expression is not useful in distinguishing GATA3 + metastases

GATA binding protein 3 (GATA3) immunohistochemical expression is commonly considered to be a sensitive and specific diagnostic marker for breast and urothelial carcinomas in surgical pathology practice. However, since its expression has been also demonstrated in other tumors, GATA3 should be better used in conjunction with other immunohistochemical markers to establish tumor primitivity in metastatic setting. Interestingly, GATA3 expression seems to be significantly correlated with androgen receptor (AR) expression in breast carcinoma. In addition, strong AR expression -defined as immunohistochemical positivity in more than 60% of tumor cells- was suggested to be 100% specific for breast origin in GATA3+ metastases. The aim of this study was to verify whether strong AR expression may actually be useful to determine primivity in GATA3+ metastatic setting. Thus, we investigated AR and GATA3 immuno-expression in a cohort of metastatic tumors derived from urothelial, breast, endometrial and salivary gland carcinomas. We did not find any GATA3 or AR expression in the metastases from endometrial or salivary gland carcinomas, while GATA3 expression was seen in the majority of metastases from urothelial or breast carcinomas. In addition, strong AR expression was seen in 73% and in 47% of metastatic breast and urothelial carcinomas, respectively. On the whole, our findings confirm that GATA3 is sensitive and specific for breast and urothelial origin in metastatic setting. According to our results, strong AR expression is not useful to distinguish breast from urothelial primitivity, as previously suggested.

Androgen receptor expression in endometrial carcinoma and its correlation with clinicopathologic features

OBJECTIVES

Recent evidence suggests a role of androgen receptor expression as a prognostic and therapeutic biomarker in endometrial carcinoma, therefore in the present study we aimed to evaluate the frequency of androgen expression in different subtypes of endometrial carcinoma and its association with clinic-pathologic features.

RESULTS

18/89 (20.2%) cases of endometrial carcinoma showed positive androgen receptor expression. On the other hand, low, moderate and high androgen receptor expression was noted in 7/89 (7.9%), 10/89 (11.2%) and 1/89 (1.1%) cases respectively. 15/77 (19.48%) of endometrioid cancers and 3/7 (42.28%) cases of serous carcinoma showed androgen receptor expression; while none of the cases of clear cell or carcinosarcoma revealed androgen receptor expression. No significant association of androgen receptor expression with various clinicopathologic features of endometrial carcinoma was noted. We found that a significant subset of endometrial cancers express androgen receptor especially a serous cancers; therefore we suggest that androgen receptor expression testing should be done in endometrial carcinoma.

Strong androgen receptor expression can aid in distinguishing GATA3+ metastases

GATA3 is a transcription factor used clinically as a marker of breast or urothelial differentiation. A marker is yet needed to distinguish this in the case of the GATA3-positive tumor of unknown origin. We tested classical markers of breast differentiation and hormonal signaling to see which correlated strongest with GATA3 expression in breast cancer and thus which could help correctly identify breast origin in the case of the GATA3-positive tumor of unknown origin. GATA3, estrogen receptor, progesterone receptor, androgen receptor (AR), HER2, GCDFP15, and mammaglobin expression was intercorrelated in a histologically diverse 259-case breast cancer tissue microarray. We show herein a uniquely high level of correlation between GATA3 and AR expression (r=0.61; 95% confidence interval 0.52-0.68) that was strongest among lobular carcinomas (r=1; 95% confidence interval 0.73-1) and stronger than any other correlation studied. Separate AR staining of 10 metastatic GATA3+ carcinomas of urothelial origin and 13 metastatic GATA3+ carcinomas of breast origin showed that strong AR staining (>60% of tumor cells) has a sensitivity of 54% and a specificity of 100% for correctly distinguishing GATA3+ carcinoma of mammary origin from urothelial origin in the metastatic setting. Androgen receptor expression is strongly correlated with GATA3 in breast cancer, particularly in tumors with lobular morphology. Strong AR expression (>60% of tumor cells) is an excellent test to rule out urothelial carcinoma in the GATA3+ metastatic setting (specificity 100%) and will effectively identify breast origin in approximately 50% of cases.