Evaluation of a displacement assay with tamoxifen as prognostic indicator in breast‐cancer patients with estrogen‐receptor‐positive tumors

• Published in: International journal of cancer 1997-11, Vol.73 (4), p.486-491
• Main Authors: Levin, Emanuel, Actis, Andrea M., Caruso, Silvana, Gass, Hugo, Romero, Raquel, Qualeta, Nicolás, Levin, Rosa W.
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents, Hormonal - metabolism; Biological and medical sciences; Breast Neoplasms - metabolism; Breast Neoplasms - mortality; Breast Neoplasms - pathology; Estradiol - metabolism; Estrogen Antagonists - metabolism; Female; Gynecology. Andrology. Obstetrics; Humans; Mammary gland diseases; Medical sciences; Neoplasm Proteins - metabolism; Neoplasm Staging; Predictive Value of Tests; Prognosis; Receptors, Estrogen - metabolism; Receptors, Progesterone - metabolism; Tamoxifen - metabolism; Tumors
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/(SICI)1097-0215(19971114)73:4<486::AID-IJC5>3.0.CO;2-W

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. Int. J. Cancer 73:486–491, 1997. © 1997 Wiley‐Liss, Inc.