Abstract P5-02-06: Digital quantification of estrogen receptor expression in normal breast in post-menopausal women with breast cancer and association with tumor subtypes

Abstract

Abstract Background: ER expression in normal breast epithelium (NBR) is higher in women with a history of breast cancer (BC) compared to controls. In adjuvant setting, metanalysis showed effective Tamoxifen treatment was restricted to ER positive cancers. However, it is also known prophylactic oophorectomy (a form of estrogen suppression) significantly reduces the incidence of BC in BRCA1 carriers. This is in contrast with the 80% rate of ER negative tumors in BRCA1 patients. The aim of this study is to quantify ER expression in NBR away from tumor in women with BC and to correlate it with BC subtypes. Methods: 204 consecutive patients were identified for whom NBR away from tumor was available. 27 reduction mammoplasty (RM) tissues from women with no history of BC were used as controls. Tissue microarrays were constructed and slides were stained with ER and scanned using Aperio XT Scan Scope. Normal terminal duct lobular epithelium was manually circled on scanned images and annotations were recorded in separate digital layers. ER staining was quantitated in marked areas of the electronic image using an optimized scoring nuclear IHC algorithm (Aperio technologies, Inc., Vista, CA). Clinical information and tumor characteristics (menopausal status, ER, HER2 expression, grade, size, number of positive nodes, stage) were recorded based on pathology reports and tumor registry data. Results: The mean ER positivity in NBR was 16 ± 12.4 % (range: 0-5-5.7%) for all patients with BC, 20.8±13.9% for postmenopausal (n=74) and 13.7 ±10.9% for peri+ premenopausal (n=170) subgroups. ER positivity was higher in patients with BC compared to those undergoing RM with no history of BC. ER positivity in NBR did not vary by tumor size, positive lymph nodes status, tumor grade, or stage in post-menopausal, and pre + perimenopausal women. Older age at diagnosis was significantly associated (p<0.0001) with ER in NBR. In post- menopausal women ER expression in NBR was significantly higher in patients with ER negative or triple negative tumors. Estrogen receptor expression in normal terminal duct lobular units of post-menopausal women with breast cancer in relation to tumor subtypes. Postmenopausal (N=74) NMean % (SD)P ValueTumor ER Status 0.05 Negative1427.4 (13.9) Positive6019.3 (13.6) Tumor HER2 Status 0.34 Negative5721.8 (14.9) Positive817.7 (5.7) Tumor Triple Negative 0.05 No5319.7 (13.6) Yes1228.5 (14.7) HER2 status was not known in some cases and was excluded from statistical calculations. Conclusion: This computer assisted image analysis study confirms ER expression in NBR increases with age and menopausal status in women with BC. We report, for the first time, a significant association between ER expression in normal breast epithelium with ER negative and triple negative cancers in post-menopausal women. Our study suggests that ER expression in normal epithelium may play a role in development of hormone receptor negative breast cancers. Citation Format: H Evin Gulbahce, Cindy Blair, Carol Sweeney, Rachel Factor, Mohamed Salama. Digital quantification of estrogen receptor expression in normal breast in post-menopausal women with breast cancer and association with tumor subtypes [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P5-02-06.