[160] Reduced or Loss of ER and PR Receptor Expression in Metastatic Breast Cancer

Rajarsi Gupta, Carmen Tornos, Meenakshi Singh, Brian O'Hea, Jingxuan Liu. Stony Brook University Medical Center, Stony Brook, NY

Background: ER and PR expression in metastatic/recurrent breast cancer can be used to confirm the origin of the tumor and determine the use of hormonal therapy.
Design: A computer search for metastatic breast cancer cases was performed from January 1998 to September 2011. The ER and PR profile of these metastases was compared to the profile of the primary breast tumor. Sixty two metastases had available ER and PR status information in both the primary tumor and the metastases. We selected the cases that have differences of 50% or more with regard to either ER or PR expression between the primary and metastatic tumors, and the cases where the ER or PR expression in the metastatic tumors decreased to 0% from any level of expression in the primary tumors. Seven cases meet the criteria.
Results: In 55 of the 62 cases (88.7%), the ER and PR profiles have differences of less than 50% or no differences at all. In seven of the 62 cases (11.2%), the differences are significant (>50%). ER expression is reduced in 3 cases; PR expression is reduced in 4 cases (Table).

Differential ER and PR expression in Metastatic Breast Cancer

Metastatic Foci	ER (%) of Metastasis	PR (%) of Metastasis	Time between Primary and Met	Primary ER (%)	Primary PR (%)	Difference in ER (%)	Difference in PR (%)
Liver	95	0	7 yrs	90	80	+5%	-80%
Femoral reamings	46	8	2 yrs	80	90	-34%	-82%
Rectum	20	0	1 yr	90	0	-70%	0%
Liver	0	0	1 yr	1	80	-1%	-80%
Upper eyelid and orbicularis muscle	30	0	2 yrs	90	5-30	-60%	-5-30%
Femoral condyle	0	0	8 yrs	90	10	-90%	-10%
Liver	Positive	4	5 yrs	80	80		-76%

Conclusions: The ER and PR expression in distant metastatic sites significantly changes in 11% of our cases, showing decreased expression of one or both of the receptors. Before using hormonal therapy to treat distant metastases, ER and PR receptor profiles should be quantitatively reassessed in the metastases and compared to the primary breast cancer. Furthermore, the differences in receptor profiles could affect the histologic identification of metastatic tumors and the response to additional hormonal therapy. Although the mechanism is still unknown, the differences between the hormone receptor expression profiles of the metastases and primary breast cancers may be due to a wide spectrum of possibilities, ranging from the intrinsic biological properties of the cancer cells to the secondary effects of treatment (cell selection versus down-regulation).
Category: Breast

Monday, March 19, 2012 1:00 PM

Poster Session II # 63, Monday Afternoon