Quantitative measures of estrogen receptor expression in relation to breast cancer-specific mortality risk among white women and black women.
BACKGROUND
The association of breast cancer patients’ mortality with estrogen receptor (ER) status (ER + versus ER-) has been well studied. However, little attention has been paid to the relationship between the quantitative measures of ER expression and mortality.


METHODS
We evaluated the association between semi-quantitative, immunohistochemical staining of ER in formalin-fixed paraffin-embedded breast carcinomas and breast cancer-specific mortality risk in an observational cohort of invasive breast cancer in 681 white women and 523 black women ages 35-64 years at first diagnosis of invasive breast cancer, who were followed for a median of 10 years. The quantitative measures of ER examined here included the percentage of tumor cell nuclei positively stained for ER, ER Histo (H)-score, and a score based on an adaptation of an equation presented by Cuzick and colleagues, which combines weighted values of ER H-score, percentage of tumor cell nuclei positively stained for the progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) results. This is referred to as the ER/PR/HER2 score.


RESULTS
After controlling for age at diagnosis, race, study site, tumor stage, and histologic grade in multivariable Cox proportional hazards regression models, both percentage of tumor cell nuclei positively stained for ER (Ptrend = 0.0003) and the ER H-score (Ptrend = 0.0004) were inversely associated with breast cancer-specific mortality risk. The ER/PR/HER2 score was positively associated with breast cancer-specific mortality risk in women with ER + tumor (Ptrend = 0.001). Analyses by race revealed that ER positivity was associated with reduced risk of breast cancer-specific mortality in white women and black women. The two quantitative measures for ER alone provided additional discrimination in breast cancer-specific mortality risk only among white women with ER + tumors (both Ptrend ≤ 0.01) while the ER/PR/HER2 score provided additional discrimination for both white women (Ptrend = 0.01) and black women (Ptrend = 0.03) with ER + tumors.


CONCLUSIONS
Our data support quantitative immunohistochemical measures of ER, especially the ER/PR/HER2 score, as a more precise predictor for breast cancer-specific mortality risk than a simple determination of ER positivity.
Huiyan
H
Ma
Yani
Y
Lu
Polly A
PA
Marchbanks
Suzanne G
SG
Folger
Brian L
BL
Strom
Jill A
JA
McDonald
Michael S
MS
Simon
Linda K
LK
Weiss
Kathleen E
KE
Malone
Ronald T
RT
Burkman
Jane
J
Sullivan-Halley
Dennis M
DM
Deapen
Michael F
MF
Press
Leslie
L
Bernstein
D000328:Adult; D014408:Biomarkers, Tumor; D044383:Black People; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality* / Q000473:pathology; D016022:Case-Control Studies; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism; D044465:White People
D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone