PREDICTIVE VALUE OF ER1D5 ANTIBODY IMMUNOSTAINING IN BREAST-CANCER - A PARAFFIN-BASED RETROSPECTIVE STUDY OF 257 CASES

Immunohistochemical detection of estrogen receptors was performed in 2 57 primary breast carcinomas using the ER1D5 monoclonal antibody on pa raffin sections. The purpose of the present study was to investigate t he potential predictive or prognostic role of ER1D5 staining in breast cancer. Two hundred fifty-seven (105 node negative and 152 node posit ive) patients, from the Hospitals of Trento and Milano-Niguarda, were studied. Survival analysis was performed in various subsets of homogen eously treated patients using the Kaplan-Meier method, ER1D5 immunorea ctivity was prognostically relevant both for relapse-free survival (RF S) and overall survival (OS) in the entire series. No statistically si gnificant difference in survival was observed in node-negative patient s. Conversely, in the node-positive subgroup, the patients with ER1D5- positive tumors showed a higher probability of 5-year survival (73.9% vs. 55.2%; p = 0.01) and a lower probability of relapse of disease (32 .8% vs, 56.5%; p = 0.002) than did the patients with ER1D5-negative tu mors. When subgroups of homogeneously treated patients were considered , ER status was not discriminant for RFS and OS in untreated node-nega tive (93 cases) and node-positive chemotherapy-treated patients (84 ca ses). Conversely, ER1D5 staining was prognostically relevant in a grou p of node-positive patients treated with tamoxifen (65 cases). The pre sent results confirm that the monoclonal antibody can be used to defin e ER status on paraffin-embedded tumors and that this assay provides p redictive information useful for the selection of patients who may ben efit from hormonal treatment.