Discordance in hormone receptor status in breast cancer during tumor progression.

Abstract

1009 Background: In the metastatic situation therapy management is often based on primary tumor characteristics such as estrogen receptor (Er) and progesterone receptor (Pr) status. Discordance of those factors may lead to altered therapy management. Methods: Breast cancers from patients in the Stockholm health care region that relapsed during 1997 to 2007 were retrospectively compared for Er and Pr status. Monoclonal antibody based biochemical or immunohistochemical/immunocytochemical methods were used for determination of hormone receptor status. Histopathological or cytological information for primary and relapse tumors were collected from original pathology reports. The pathology laboratory at Karolinska University Hospital continuously participate in quality assurance programs for receptor analysis. Results: In 486 and 456 patients, Er and Pr information were available from the primary tumor and one or more recurrent sites, resulting in 679 and 630 pairs, respectively. For Er, 27% of patients changed from positive in primary tumor to negative in relapse tumor and 8% changed from negative to positive. Pr status changed in 38% of patients from positive to negative and 5% changed from negative to positive. In our univariate analysis the Er groups (concordantly positive/negative and two discordant), showed significantly different overall survival (log rank p<0.0001). The survival was worse for those with Er-negative relapse tumors compared to Er-positive, independent of primary Er tumor status. Conclusions: This study demonstrates that in nearly every third patient with breast cancer, the hormone receptor status changes during tumor progression. Thus, Er status of metastatic sites has impact on survival and therapy management of metastatic disease is not optimum when based on primary tumor characteristics. Altered management through tumor progression may improve survival, avoid over treatment, and support more frequent morphological confirmation of recurrent site. However, tumor heterogeneity, clonal selection by different adjuvant therapies, and methodological issues regarding receptor determinations may contribute to our findings and will be discussed further at presentation. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Affybodies, Amgen, AstraZeneca, GlaxoSmithKline, I3Innovus, Onyx/Bayer, Pfizer, sanofi-aventis, Tapestry Pharmaceuticals AstraZeneca, Pfizer, Roche Merck, Pfizer, Roche