P5-13-10: Discordance of Estrogen Receptor and HER-2/neu Status Can Be Seen between First and Subsequently Biopsied Metastatic Lesions in Breast Cancer.

Abstract

Abstract Background We have previously reported discordance between primary and first metastasis for both estrogen receptor (ER) and HER-2/neu (HER 2) status (Breast Cancer Res Treat 2005;90:65–70 and Breast Cancer Res Treat 2009;113:301–6). Because biomarker status is the primary determinant for targeted therapy, changes in biomarkers can impact recommendations for systemic treatment. Materials and Methods: In order to evaluate the possibility of further discordance with the development of additional metastatic sites, we examined the ER and HER 2 status of primary and first and subsequently biopsied breast cancer metastasis. In most cases, the subsequent site of metastasis was the second detected metastasis. Pathology reports were reviewed from 65 patients with biopsy proven first and additional metastasis; however, immunostain results were not available for all three timepoints for all patients. Sites of biopsied metastasis included lung, liver, bone, chest wall, and central nervous system. Results: The time between the initial diagnosis and first metastasis was 102 (3-676) months [Median (Range)], and the time between the first and subsequent metastasis was 60 (6-273) months. For ER, there was discordance between the primary lesion and either the first or subsequent metastasis in 18 of 65 cases (27.7%). Discordance of the ER occurred between the first and subsequent metastasis in 12 (18%) of cases. Three patterns of ER discordance occurred in these 12 cases: 4 cases of both primary and first metastasis negative with subsequent metastasis positive; 3 cases of primary positive, first metastasis negative, and subsequent metastasis positive, and 5 cases of primary and first metastasis positive and subsequent metastasis negative. For HER 2, discordance was detected between the primary and either first or subsequent metastasis in 11 of 36 cases (30.6%). Further discordance between the first and subsequent metastatic lesions occurred in 8 of 51 (16%) of cases. Conclusions: A significant level of discordance for either ER or HER 2 was detected between first and subsequent metastatic breast cancer lesions. For breast cancer patients with new metastasis, consideration of reevaluating ER and HER-2/neu status may be worthwhile. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-13-10.