low weight(or BMI) is a risk factor for her2+ breast cancer

[Lani]

I previously posted an article which showed no correlation between post-treatment weight-gain and recurrence.

Others added that they had been thin or lost considerable weight prior to their diagnoses.

You may find this abstract from the European breast cancer conference in Nice last week interesting--it seems to me that it just shows that her2+ breast cancer is a different "beast" than other breast cancers!--don't know if this holds up in pre-menopausal her2 breast cancer :

Weight and body mass index (BMI) affect HER2 expression in postmenopausal breast cancer



Citation: European Journal of Cancer Supplements Volume 4, No. 2, March 2006, page 68

T. Van Mieghem1, K. Leunen1, N. Pochet2, B. De Moor2, F. Amant13, I. Vanden Bempt4, R. Drijkoningen4, M.R. Christiaens35, I. Vergote1, P. Neven13

1University Hospitals Leuven, Dept. of Obstetrics and Gynaecology, Leuven, Belgium
2KULeuven, ESAT, Leuven, Belgium
3University Hospitals Leuven, Multidisciplinary Breast Center, Leuven, Belgium
4University Hospitals Leuven, Dept. of Pathology, Leuven, Belgium
5University Hospitals Leuven, Dept. of Surgery, Leuven, Belgium

Background: In our population, HER-2 is expressed in 10.9% of primary breast cancers (J Clin Path 2005;58:611–6). Postmenopausal obesity is a risk factor for hormone sensitive tumours. These tumours are more likely HER-2 negative (Breast Cancer Res Treat 2005;91:81–7). We therefore hypothesised that postmenopausal obesity is associated with fewer HER-2 positive tumours.
Patients and Methods: Between January 1st 2002 and December 31st 2004, 549 postmenopausal women with a unilateral, not previously treated, operable breast cancer were evaluated the evening prior to operation for body weight, height, abdominal and hip circumference. Waist-to-hip ratio (WHR) and BMI [Weight/(Length in meters)2] were calculated. HER-2 staining was done by immunohistochemistry (MoAbCB11) and scored between 0 and 3+. HER-2 negativity was defined as 0, 1+ or 2+; HER-2 positivity as 3+. We compared HER-2 negative patients with HER-2 positive patients for all parameters of body composition and assessed the frequency of HER-2 positivity in each quartile from the lowest (Q1) to the highest (Q4) for these same parameters.
Results: Length and WHR were not significantly different between patients with HER-2 negative and HER-2 positive tumours. Abdominal and hip circumference were lower in HER-2 positive patients. This trend however, was not statistically significant. In Table 1 mean values for weight and BMI are compared between HER-2 negative and HER-2 positive patients. Table 2 shows the proportion of HER-2 positive tumours per quartile for weight and BMI in all patients.
Table 1. Comparison of mean values for weight and BMI between HER-2 negative and HER-2 positive patients

HER-2 negative HER-2 positive P-value
N Mean±SD N Mean±SD
Weight (kg) 474 69.19±13.18 58 65.09±11.29 0.0215
BMI (kg/m2) 472 26.98±9.21 56 24.93±4.27 0.0085
SD: standard deviation.


Table 2. Proportion of HER-2 positive tumours per quartile for weight and BMI in all patients (N = 549)

HER-2 positivity (%) P-value
Q1 Q2 Q3 Q4 (Q1–Q4)
Weight 16.30 10.32 9.93 6.92 0.0214
BMI 14.50 12.21 10.69 5.19 0.0127


Conclusion: Low weight and low BMI are risk factors for HER-2 positivity in postmenopausal women with breast cancer. The linear decrease in HER-2 positivity per increasing quartile for both parameters suggests our hypothesis may be correct. Larger numbers of HER-2 positive cases may be required to confirm our findings for other parameters of body composition.