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Abstract: Introduction: Sentinel lymph node (SLN) biopsy allows a more detailed examination of a smaller number of lymph nodes in patients with clinically node negative breast cancer. Immunohistochemistry detects small tumour burden not routinely seen on haematoxylin and eosin (H&E). The significance of such findings remains to be fully elucidated. Aim: To assess the axillary disease burden of patients in whom the sentinel lymph node biopsy was positive on immunohistochemistry and negative on H and E. Methods: An analysis of patients who underwent SLN mapping for breast cancer at St Vincent''s University Hospital from January 1st, 2000 to December 31st, 2006 was conducted. All SLNs were assessed by serial H&E and IHC sections. Patients with micrometastases (0.2–2mm) underwent a completion axillary lymph node dissections (CLND). Patients with ITC (<0.2mm) were individually discussed and a CLND was performed selectively based on additional clinicopathological criteria and patient preference. Analysis of the additional nodes from CLND was performed. Patients were followed for a median of 27 months (range 12–72 months). Results: 1076 patients who underwent SLN were included for analysis. 211 (20%) had a positive SLN biopsy using H&E. Forty-nine patients (5%) had a negative SLN on H&E which was positive on IHC. Of these, 15 had micrometastases and underwent a CLND. Two had further axillary nodal disease. ITC were found in the remaining 34 patients. Sixteen of these patients underwent a CLND. Five of this group had further nodal disease. Conclusion: Micrometastases and isolated tumour cells, detected only by immunohistochemical analysis of sentinel lymph nodes, are associated with further positive nodes in the axilla in up to 15% of patients. This upstaging of disease may impact upon patient outcome. [Copyright &y& Elsevier]

The oestrogen receptor (ER) interacts with coactivator proteins to modulate genes central to breast tumour progression. Oestrogen receptor is encoded for by two genes, ER-aand ER-ß. Although ER-ahas been well characterized, the role of ER-ßas a prognostic indicator remains unresolved. To determine isoform-specific expression of ER and coexpression with activator proteins, we examined the expression and localisation of ER-a, ER-ßand the coactivator protein steroid receptor coactivator 1 (SRC-1) by immunohistochemistry and immunofluorescence in a cohort of human breast cancer patients (n=150). Relative levels of SRC-1 in primary breast cultures derived from patient tumours in the presence ofß-oestradiol and tamoxifen was assessed using Western blotting (n=14). Oestrogen receptor-ßprotein expression was associated with disease-free survival (DFS) and inversely associated with the expression of HER2 (P=0.0008 and P<0.0001, respectively), whereas SRC-1 was negatively associated with DFS and positively correlated with HER2 (P<0.0001 and P<0.0001, respectively). Steroid receptor coactivator 1 protein expression was regulated in response toß-oestradiol or tamoxifen in 57%of the primary tumour cell cultures. Protein expression of ER-ßand SRC-1 was inversely associated (P=0.0001). The association of ER-ßprotein expression with increased DFS and its inverse relationship with SRC-1 suggests a role for these proteins in predicting outcome in breast cancer.British Journal of Cancer (2004) 91, 1687-1693. doi:10.1038/sj.bjc.6602156 www.bjcancer.com Published online 12 October 2004 [ABSTRACT FROM AUTHOR]

Background: In human breast cancer, the growth factor receptor HER2 is associated with disease progression and resistance to endocrine treatment. Growth factor induced mitogen activated protein kinase activity can phosphorylate not only the oestrogen receptor, but also its coactivator proteins AIB1 and SRC-1. Aim: To determine whether insensitivity to endocrine treatment in HER2 positive patients is associated with enhanced expression of coactivator proteins, expression of the HER2 transcriptional regulator, PEA3, and coregulatory proteins, AIB1 and SRC-1, was assessed in a cohort of patients with breast cancer of known HER2 status. Methods: PEA3, AIB1, and SRC-1 protein expression in 70 primary breast tumours of known HER2 status (HER2 positive, n = 35) and six reduction mammoplasties was assessed using immunohistochemistry. Colocalisation of PEA3 with AIB1 and SRC-1 was determined using immunofluorescence. Expression of PEA3, AIB1, and SRC-1 was correlated with clinicopathological parameters. Results: In primary breast tumours expression of PEA3, AIB1, and SRC-1 was associated with HER2 status (p = 0.0486, p = 0.0444, and p = 0.0012, respectively). In the HER2 positive population, PEA3 expression was associated with SRC-1 (p = 0.0354), and both PEA3 and SRC-1 were significantly associated with recurrence on univariate analysis (p = 0.0345; p<0.0001). On multivariate analysis, SRC-1 was significantly associated with disease recurrence in HER2 positive patients (p = 0.0066). Conclusion: Patients with high expression of HER2 in combination with SRC-1 have a greater probability of recurrence on endocrine treatment compared with those who are HER2 positive but SRC-1 negative. SRC-1 may be an important predictive indicator and therapeutic target in breast cancer. [ABSTRACT FROM AUTHOR]