GPR30 and HER-2 Expression in Invasive and Metastatic Breast Cancer.

Abstract

Abstract Background: GPR30 expression, a new estrogen receptor, has been previously associated with HER-2, tumor size and metastasis in invasive breast cancer (BC) but its role in paired normal (N), invasive (I), and metastatic (M), samples is unknown. We described GPR30 and HER-2 expression in a collection of paired N/I/M samples, derived from the same individual.Materials and Methods: GPR30 and HER-2 expression was assessed by immunohistochemistry (IHC) in tissue microarrays, containing paraffin-embedded cores from 100 patients diagnosed with invasive BC. N and M samples were also available from the same patient. GPR30 expression was evaluated by an H-score (Intensity (0, negative; 1+, weak; 2+, moderate; 3+, strong) x Percentage of stained epithelial cells). HER-2 expression was evaluated per standard criteria. Log rank tests and Wald tests were employed to assess the clinical impact of these molecular targets on patient outcome based on Kaplan-Meier Product estimator and Cox Proportional Hazard Regression.Results: GPR30 was expressed in 50%, 76%, and 72% of N, I and M, respectively, samples. HER-2 (3+) was found in 14% and 18% of I and M samples, respectively. GPR30 expression in I cases correlated with expression in M cases, and HER-2 expression in I but not M cases. GPR30 expression in M cases correlated with expression in HER-2 expression in M cases. HER-2 expression in I cases correlated with expression in M samples (P<0.05 for all comparisons). GPR30 and HER-2 expression were not associated with grade or stage (P>0.05). GPR30 expression in I or M samples was not associated with either overall survival (OS) or BC-specific survival (BCSS)(P>0.5). HER-2 expression was marginally associated with OS in I (P=0.06; Hazard Ratios (HR): 1.91; 95%CI: 0.956, 3.83) but not in M (P=0.23) cases. HER-2 was significantly associated with BCSS in I cases (P=0.03; HR: 2.39; 95%CI: 1.07, 5.32) and marginally in M (P=0.08) cases.Discussion: A previous study suggested that GPR30 expression predicted the development of metastasis. We found high GPR30 expression in both the primary and metastatic sample but the difference was not significant. While GPR30 expression was not associated with OS or BCSS, HER-2 expression was marginally associated with OS and significantly associated with BCSS in invasive cases. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4158.