title: Evaluation of a displacement assay with tamoxifen as prognostic indicator in breast-cancer patients with estrogen-receptor-positive tumors.
abstract: A displacement assay with tamoxifen, based on the relative binding affinity of tamoxifen and estradiol for the estrogen receptor (ER), was proposed in 1990 as prognostic indicator for breast-cancer patients. Validation of its predictive results in relation to the outcome of 73 patients with ER+ tumors is analyzed. ER, progesterone receptor (PgR) determinations and other conventional prognostic factors in relation to the displacement assay, were considered. Displacement assay results allowed ER+ tumors to be grouped as displaceable (D) or weakly displaceable (WD), with the implication that D tumors should respond better to tamoxifen (Tam) administration. Survival and disease-free interval curves showed highly significant differences between patients with ER+ D and ER+ WD tumors. For survival, including all tumor stages, 73.9% of patients were alive at 9 years after surgery in the group with D tumors and 37.0% in the group with WD tumors (p < 0.005); relative contribution of the different stages is analyzed. Addition of axillary-node number increased the prognostic significance of displacement categories for survival and disease-free interval. PgR determination as another ER functional expression failed to show significant differences for survival and disease-free interval between ER+ PgR+ and ER+ PgR- tumors. Thus, results from the displacement assay and from PgR determinations reflect 2 independent ER functional expressions. Displacement assay data appear as reliable prognostic indicators of breast-cancer outcome, and contribute to more appropriate treatment decisions in this pathology.
authors.affiliation: Departamento Bioquimica Humana, Facultad de Medicina, UBA, Buenos Aires, Argentina. levin@fmuba.sld.ar
authors.forename: E
authors.initials: E
authors.lastname: Levin
authors.forename: A M
authors.initials: AM
authors.lastname: Actis
authors.forename: S
authors.initials: S
authors.lastname: Caruso
authors.forename: H
authors.initials: H
authors.lastname: Gass
authors.forename: R
authors.initials: R
authors.lastname: Romero
authors.forename: N
authors.initials: N
authors.lastname: Qualeta
authors.forename: R W
authors.initials: RW
authors.lastname: Levin
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D004958:Estradiol / Q000378:metabolism*; D004965:Estrogen Antagonists / Q000378:metabolism*; D005260:Female; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011379:Prognosis; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism; D013629:Tamoxifen / Q000378:metabolism*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D004965:Estrogen Antagonists; D009363:Neoplasm Proteins; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D013629:Tamoxifen; D004958:Estradiol