Abstract P2-10-04: The clinicopathological features of androgen receptor expression in primary HER2-positive breast carcinomas
Authors: Yamashita T , Aruga T , Miyamoto H , Kitagawa D , Idera N , Goto R , Horiguchi K , Kuroi K 
Published: August 2014

Background: Human epidermal growth factor receptor 2 (HER2)-positive breast carcinomas are aggressive subtypes associated with a variable response to systemic therapies. HER2-positive breast carcinomas are not homogeneous, and it has been reported that androgen receptor (AR) signaling is an important determinant of cell growth and relation with HER3 expression. The aim of this study was to investigate the clinicopathological significance of AR expression in primary HER2-positive breast carcinomas.

Patients and Methods: 102 primary HER2-positive breast tumor samples were obtained from patients operated on at the Cancer and Infectious Disease Center, Tokyo Metropolitan Komagome Hospital from 2001 to 2010. 92 tumors were IHC (HercepTest) score 3, whereas 10 were IHC score 2 and FISH- positive. We evaluated AR using immunohistochemistry. Tumors with equal or more than 10% nuclear-stained cells were determined to be positive for AR and the relationship between AR and clinicopathological parameters was analyzed.

The expression of HER3 was evaluated by immunohistochemistry using the following scoring system: 0 (no staining), 1 (less than 20% of cells stained or weak staining), 2 (more than or equal to 20% of cells stained, or strong staining) and the relation with AR expression was examined.

The differences among variables were calculated by chi-square test.

Results: The median age of all patients was 56 years old (from 31 to 84). AR-positive carcinomas corresponded to 37(36.2%) of 102 HER2-positive breast carcinomas. The median age of AR-positive patients was 54 years old while that of AR-negative patients was 57 years old. There was no significant difference between the two groups.

AR-positive carcinomas were not associated with ER and progesterone receptor (PgR) co-expression and nuclear grade. The stage distribution of AR-positive patients was: stage I(n = 23), stage IIA(n = 11), stage IIB (n = 3), and averaged 18.5mm in tumor size, while AR-negative patients distributed as stage I(n = 16), stage IIA(n = 27), stage IIB (n = 15), stage IIIA(n = 5), stage IIIB(n = 2), and averaged 23.7mm in size. AR-positive carcinomas were associated with larger pathological tumor size and more advanced clinical stages, though lymph node involvement did not differ between the two groups.

The HER3 expression score distribution was: scrore 0 (n = 14), score 1 (n = 54), score 2 (n = 34). The expression of HER3 was not associated with clinicopathological parameters. Furthermore, there was no significant relation between AR expression and HER3 expression.

Median follow-up interval was 63 months. 20 patients (19.6%) suffered recurrence. Four patients suffered recurrence in the AR-positive group while there were 16 patients in the AR-negative group. AR-positive patients had significant better prognosis in recurrence than AR-negative patients.

Conclusion: Among HER2-positive breast carcinomas, AR-positive carcinomas have the tendency to be smaller in tumor size and of early clinical stage compared with those that are AR-negative. The expression of AR might be a better prognostic factor in HER2-positive breast carcinomas.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-10-04.