Triple negative breast cancer: clinical characteristics in the different histological subtypes.

PURPOSE: To investigate the clinical behavior of triple negative breast cancer (TNC), including age distribution, occurrence of LN (lymph node) invasion and prognosis in different histological subtypes. METHODS: For this cohort study we used data on 476 patients with newly diagnosed TNC at the University Hospitals Leuven (Belgium) between 1999 and 2009. Of these, 395 received upfront surgery, 68 neoadjuvant chemotherapy and 21 had metastases at diagnosis. RESULTS: Apocrine and invasive lobular TNC occur more often in older patients compared to IDC-NOS. Of the primarily operated patients with TNC, 35.1% has pathological LN involvement. There were no significant differences in nodal invasion between different histological subtypes, but most subtypes contained few patients. In contrast to previous reports, 6/14 of apocrine TNC had LN involvement. Disease free survival (DFS) was different in different histological subtypes, but group sizes were insufficient to be able to draw firm conclusions. Within the histologically 'homogeneous' IDC-NOS group with primary surgery and outcome data (n = 300), DFS with 3.5 year median follow-up decreased with increasing age, but chemotherapy and radiotherapy were much less frequently given with increasing age. In multivariable analysis, lower age, presence of LN involvement, lack of administration of chemotherapy and radiotherapy were significant predictors of relapse. CONCLUSION: TNC is not a uniform disease. Different histological subtypes have different age distribution and behavior. The prognosis of the most common histological subgroup, IDC-NOS, is better in older patients, but this is counterbalanced by significantly decreased use of chemotherapy and radiotherapy.

Proteolytic processing of ErbB4 in breast cancer.

ErbB4 is a receptor tyrosine kinase that can signal by a mechanism involving proteolytic release of intracellular and extracellular receptor fragments. Proteolysis-dependent signaling of ErbB4 has been proposed to be enhanced in breast cancer, mainly based on immunohistochemical localization of intracellular epitopes in the nuclei. To more directly address the processing of ErbB4 in vivo, an ELISA was developed to quantify cleaved ErbB4 ectodomain from serum samples. Analysis of 238 breast cancer patients demonstrated elevated quantities of ErbB4 ectodomain in the serum (≥ 40 ng/mL) in 21% of the patients, as compared to 0% of 30 healthy controls (P = 0.002). Significantly, the elevated serum ectodomain concentration did not correlate with the presence of nuclear ErbB4 immunoreactivity in matched breast cancer tissue samples. However, elevated serum ectodomain concentration was associated with the premenopausal status at diagnosis (P = 0.04), and estradiol enhanced ErbB4 cleavage in vitro. A 3.4 Å X-ray crystal structure of a complex of ErbB4 ectodomain and the Fab fragment of anti-ErbB4 mAb 1479 localized the binding site of mAb 1479 on ErbB4 to a region on subdomain IV encompassing the residues necessary for ErbB4 cleavage. mAb 1479 also significantly blocked ErbB4 cleavage in breast cancer cell xenografts in vivo, and the inhibition of cleavage was associated with suppression of xenograft growth. These data indicate that ErbB4 processing is enhanced in breast cancer tissue in vivo, and that ErbB4 cleavage can be stimulated by estradiol and targeted with mAb 1479.

Vitamin D status at breast cancer diagnosis: correlation with tumor characteristics, disease outcome, and genetic determinants of vitamin D insufficiency.

We correlated serum 25-hydroxyvitamin D(3) (25OHD) levels with tumor characteristics and clinical disease outcome in breast cancer patients and assessed the impact of genetic determinants of vitamin D insufficiency. We collected serum from 1800 early breast cancer patients at diagnosis, measured 25OHD by radioimmunoassay (RIA), and determined genetic variants in vitamin D-related genes by Sequenom. Multivariable regression models were used to correlate 25OHD levels with tumor characteristics. Cox proportional hazard models were used to assess overall survival (OS), disease-specific survival (DSS), and disease-free interval (DFI). Lower 25OHD serum levels significantly correlated with larger tumor size at diagnosis (P = 0.0063) but not with lymph node invasion, receptor status, or tumor grade. Genetic variants in 25-hydroxylase (CYP2R1) and vitamin D-binding (DBP) protein significantly determined serum 25OHD levels but did not affect the observed association between serum 25OHD and tumor size. High serum 25OHD (>30 ng/mL) at diagnosis significantly correlated with improved OS (P = 0.0101) and DSS (P = 0.0192) and additionally had a modest effect on DFI, which only became apparent after at least 3 years of follow-up. When considering menopausal status, serum 25OHD had a strong impact on breast cancer-specific outcome in postmenopausal patients [hazards ratios for 25OHD >30 ng/mL versus ≤30 ng/mL were 0.15 (P = 0.0097) and 0.43 (P = 0.0172) for DSS and DFI, respectively], whereas no association could be demonstrated in premenopausal patients. In conclusion, high vitamin D levels at early breast cancer diagnosis correlate with lower tumor size and better OS, and improve breast cancer-specific outcome, especially in postmenopausal patients.