Abstract P6-05-08: Significant heterogeneity in ERalpha and PR receptor status in different distant breast cancer metastases of the same patient

Abstract

Abstract Purpose: Receptor conversion for estrogen receptor alpha (ERα), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) in single distant breast cancer metastases has been described before. However, most patients develop multiple metastases. Heterogeneity in receptor status between different metastases of the same patient has not been studied, probably since such material is very rare. The consequence of such heterogeneity would mean that as many metastases as possible need to be biopsied to re-assess receptor status. We therefore aimed to study heterogeneity of receptor status between different distant metastases of the same patient in a relatively large group by re-staining all primary tumors and metastases with current optimal immunohistochemical methods on full sections. Material and methods: Formalin fixed paraffin embedded tissue of primary breast carcinomas and corresponding multiple (≥2) distant metastases from 38 female patients were collected from several pathology departments in The Netherlands and stained for ERα, PR and HER2 by IHC. We evaluated the heterogeneity of receptor status between the metastases and the correlation with the primary tumor. Results: In the 4 cases that showed ER conversion, 2 (50%) showed heterogeneity in receptor expression between different metastases of the same patient. Of the 17 cases that showed PR conversion, 12 cases (71%) showed heterogeneity in expression between metastases. There were no changes in the receptor profile of primary breast cancer to their metastases for HER2 in this group. Conclusion: In a significant number of metastatic breast cancer patients, there is heterogeneity in ER and PR receptor status between different breast cancer metastases of the same patient. This implies that as many metastases as possible need to be biopsied to re-assess receptor status and set the optimal indication for hormonal therapy in these patients. Alternatively, non-invasive assessment of the receptor status by molecular imaging may be an easier future way to assess receptor status of all metastatic lesions. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-05-08.