Body mass index and HER-2 overexpression in breast cancer patients over 50 years of age.
OBJECTIVE
In breast cancer, in vitro as well as in vivo experiments have shown an inverse relationship between HER-2 and steroid hormone receptors. It is unknown whether circulating estrogens affect HER-2 expression. We hypothesize that the postmenopausal body mass index (BMI) as a surrogate marker for bio-available estrogens, is inversely associated with HER-2 over-expression.


METHODS
A total of 535 women over age 50 or with known postmenopausal status, with a unilateral, not previously treated, operable breast cancer were evaluated the evening prior to surgery for body weight, height, abdominal and hip circumference over a 3 years period. Waist-to-hip ratio (WHR) and BMI were calculated. HER-2, estrogen receptor and progesterone receptor staining was done by immunohistochemistry. All tumours with DAKO 2+ staining were submitted for HER-2 detection by FISH analysis. HER-2 was defined as positive if DAKO 3+ or FISH positive. We assessed the frequency of HER-2 positivity in each of 6 quantiles for all parameters of body composition and tested for a trend in HER-2 expression across the 6 quantiles. Furthermore, we investigated whether BMI contributed, together with other known predictors for HER-2, in a standard multivariate logistic regression model that predicts HER-2 over-expression.


RESULTS
There is a decrease in HER-2 over-expression per increasing quantile of BMI. In a multivariate model-including both steroid receptors-BMI remains an independent predictor for HER-2 over-expression.


CONCLUSIONS
In women over age 50 or with known postmenopausal status with an operable breast cancer, there is an inverse association between BMI and HER-2 over-expression.
Van Mieghem
T
T
Department of Obstetrics and Gynaecology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium.
Leunen
K
K
Pochet
N
N
De Moor
B
B
De Smet
F
F
Amant
F
F
Berteloot
P
P
Timmerman
D
D
Vanden Bempt
I
I
Drijkoningen
R
R
Wildiers
H
H
Paridaens
R
R
Smeets
A
A
Hendrickx
W
W
Van Limbergen
E
E
Christiaens
M R
MR
Vergote
I
I
Neven
P
P
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001943:Breast Neoplasms / Q000737:chemistry* / Q000235:genetics / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D016015:Logistic Models; D008875:Middle Aged; D016017:Odds Ratio; D017698:Postmenopause; D011446:Prospective Studies; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis* / Q000235:genetics; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis; D018570:Risk Assessment; D015854:Up-Regulation; D049629:Waist-Hip Ratio
D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human