Estrogen receptors (ER) in human breast cancer. The significance of a new prognostic factor based on both ER protein and ER mRNA contents.

Abstract

BACKGROUND:

The response to endocrine therapy is not entirely predictable from the estrogen receptor (ER) and progesterone receptor (PgR) status of primary breast tumors. The authors previously proposed a new prognostic factor, ER.R, which was based on both ER protein and mRNA levels. A previous analysis of 88 primary breast carcinomas showed that ER.R permits the identification of a subset of ER-positive women with a higher risk of early relapse. The purpose of the present study was to confirm the prognostic significance of ER.R.

METHODS:

Estrogen receptor protein levels were determined for 171 patients with primary breast cancer either by radio-ligand binding assay (ER-LBA) or enzyme immunoassay (ER-EIA). Estrogen receptor, pS2, and c-erbB-2 mRNA were measured by Northern blot analysis.

RESULTS:

ER.R factor is determined by calculating the ratio of the values (ER protein in fentomoles per milligram of total proteins) to (ER mRNA in picograms per 4 micrograms of total RNA). A cutoff value of 1.5 (protein levels measured by ER-LBA) or 3 (protein levels measured by ER-EIA) discriminate the two ER.R1 (lower ratio) and ER.R2 (higher ratio) subgroups, which present a significantly lower and higher risk of early relapse, respectively. No association was found between ER.R status and either PgR status or c-erbB-2 and pS2 expression. According to a Cox multivariate analysis for disease free survival, the two stronger factors in predicting a poor prognosis were c-erbB-2 overexpression and ER.R2. In the present analysis, ER.R2 was a stronger predictor of recurrence than was ER negativity.

CONCLUSIONS:

In accordance with the authors' first published data, the analysis of a larger population with a longer follow-up showed that ER.R2 keeps its significance to predict a poorer outcome for a patient, regardless of which assay was used to quantify ER.

• Authors: M Gotteland, E May, F May-Levin, G Contesso, J C Delarue, H Mouriesse
• Journal: Cancer (Cancer) Vol. 74 Issue 3 Pg. 864-71 (Aug 01 1994) ISSN: 0008-543X [Print] United States
• PMID: 7913659 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Carrier Proteins
• Proto-Oncogene Proteins
• RNA, Messenger
• Receptors, Estrogen
• estrophilin
• ErbB Receptors
• Receptor, ErbB-2

Topics

• Breast Neoplasms (chemistry, mortality)
• Carrier Proteins (analysis)
• ErbB Receptors (analysis)
• Female
• Humans
• Immunoenzyme Techniques
• Prognosis
• Proto-Oncogene Proteins (analysis)
• RNA, Messenger (analysis)
• Radioligand Assay
• Receptor, ErbB-2
• Receptors, Estrogen (analysis, genetics)