Androgen receptor (AR) expression in 400 breast carcinomas: is routine AR assessment justified?

Am J Cancer Res. 2014 Jul 16;4(4):353-68. eCollection 2014.


Background: Triple negative breast carcinomas (TNBC) do not benefit from hormonal or Herceptin therapies. In search of novel therapeutic targets for TNBC, interest is escalating in a subset of these tumors that are androgen receptor (AR) positive with potential benefit from anti-androgen therapy. Against this background, the frequency of AR expression alone and in combination with other markers and morphologic features was assessed to identify TNBC subtypes for targeted therapy.

Methods: 400 consecutive invasive mammary carcinomas with known estrogen receptor (ER), progesterone receptor (PR), androgen receptor (AR) and HER2 status were selected for study. The frequency of AR positivity alone or in combination with other markers was recorded with specific attention to the morphology of AR+ TNBCs. Ki67 was evaluated in selected group of cases. ASCO/CAP guidelines were used for interpretation of the various biomarkers.

Results: Of the 400 tumors, 32 (8%) carcinomas were quadruple negative (ER-, PR-, AR-, Her2-), while 50 tumors (12.5%) were triple negative (ER-, PR-, Her2-); 18 (36%) of the triple negative tumors were AR positive and 10 (55%) of these were classic apocrine carcinomas. Fourteen cases, all apocrine carcinomas, were AR and Her2 positive. All 32 QN carcinomas were poorly differentiated and they had the highest Ki67 labeling index.

Conclusion: The relatively high proportion of AR+ tumors (36%) among the 50 triple negative carcinomas is an important finding in support of routine assessment of AR in at least all TNBCs and apocrine carcinomas as a potential target for therapy.

Keywords: Androgen receptor (AR); HER2; breast cancer; estrogen receptor (ER); progesterone receptor (PR).