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      Tumor-specific HMG-CoA reductase expression in primary premenopausal breast cancer predicts response to tamoxifen

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          Abstract

          Introduction

          We previously reported an association between tumor-specific 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMG-CoAR) expression and a good prognosis in breast cancer. Here, the predictive value of HMG-CoAR expression in relation to tamoxifen response was examined.

          Methods

          HMG-CoAR protein and RNA expression was analyzed in a cell line model of tamoxifen resistance using western blotting and PCR. HMG-CoAR mRNA expression was examined in 155 tamoxifen-treated breast tumors obtained from a previously published gene expression study (Cohort I). HMG-CoAR protein expression was examined in 422 stage II premenopausal breast cancer patients, who had previously participated in a randomized control trial comparing 2 years of tamoxifen with no systemic adjuvant treatment (Cohort II). Kaplan-Meier analysis and Cox proportional hazards modeling were used to estimate the risk of recurrence-free survival (RFS) and the effect of HMG-CoAR expression on tamoxifen response.

          Results

          HMG-CoAR protein and RNA expression were decreased in tamoxifen-resistant MCF7-LCC9 cells compared with their tamoxifen-sensitive parental cell line. HMG-CoAR mRNA expression was decreased in tumors that recurred following tamoxifen treatment ( P < 0.001) and was an independent predictor of RFS in Cohort I (hazard ratio = 0.63, P = 0.009). In Cohort II, adjuvant tamoxifen increased RFS in HMG-CoAR-positive tumors ( P = 0.008). Multivariate Cox regression analysis demonstrated that HMG-CoAR was an independent predictor of improved RFS in Cohort II (hazard ratio = 0.67, P = 0.010), and subset analysis revealed that this was maintained in estrogen receptor (ER)-positive patients (hazard ratio = 0.65, P = 0.029). Multivariate interaction analysis demonstrated a difference in tamoxifen efficacy relative to HMG-CoAR expression ( P = 0.05). Analysis of tamoxifen response revealed that patients with ER-positive/HMG-CoAR tumors had a significant response to tamoxifen ( P = 0.010) as well as patients with ER-positive or HMG-CoAR-positive tumors ( P = 0.035). Stratification according to ER and HMG-CoAR status demonstrated that ER-positive/HMG-CoAR-positive tumors had an improved RFS compared with ER-positive/HMG-CoAR-negative tumors in the treatment arm ( P = 0.033); this effect was lost in the control arm ( P = 0.138), however, suggesting that HMG-CoAR predicts tamoxifen response.

          Conclusions

          HMG-CoAR expression is a predictor of response to tamoxifen in both ER-positive and ER-negative disease. Premenopausal patients with tumors that express ER or HMG-CoAR respond to adjuvant tamoxifen.

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          Most cited references22

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          Tissue microarrays for high-throughput molecular profiling of tumor specimens.

          Many genes and signalling pathways controlling cell proliferation, death and differentiation, as well as genomic integrity, are involved in cancer development. New techniques, such as serial analysis of gene expression and cDNA microarrays, have enabled measurement of the expression of thousands of genes in a single experiment, revealing many new, potentially important cancer genes. These genome screening tools can comprehensively survey one tumor at a time; however, analysis of hundreds of specimens from patients in different stages of disease is needed to establish the diagnostic, prognostic and therapeutic importance of each of the emerging cancer gene candidates. Here we have developed an array-based high-throughput technique that facilitates gene expression and copy number surveys of very large numbers of tumors. As many as 1000 cylindrical tissue biopsies from individual tumors can be distributed in a single tumor tissue microarray. Sections of the microarray provide targets for parallel in situ detection of DNA, RNA and protein targets in each specimen on the array, and consecutive sections allow the rapid analysis of hundreds of molecular markers in the same set of specimens. Our detection of six gene amplifications as well as p53 and estrogen receptor expression in breast cancer demonstrates the power of this technique for defining new subgroups of tumors.
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            A comparison of letrozole and tamoxifen in postmenopausal women with early breast cancer.

            The aromatase inhibitor letrozole is a more effective treatment for metastatic breast cancer and more effective in the neoadjuvant setting than tamoxifen. We compared letrozole with tamoxifen as adjuvant treatment for steroid-hormone-receptor-positive breast cancer in postmenopausal women. The Breast International Group (BIG) 1-98 study is a randomized, phase 3, double-blind trial that compared five years of treatment with various adjuvant endocrine therapy regimens in postmenopausal women with hormone-receptor-positive breast cancer: letrozole, letrozole followed by tamoxifen, tamoxifen, and tamoxifen followed by letrozole. This analysis compares the two groups assigned to receive letrozole initially with the two groups assigned to receive tamoxifen initially; events and follow-up in the sequential-treatment groups were included up to the time that treatments were switched. A total of 8010 women with data that could be assessed were enrolled, 4003 in the letrozole group and 4007 in the tamoxifen group. After a median follow-up of 25.8 months, 351 events had occurred in the letrozole group and 428 events in the tamoxifen group, with five-year disease-free survival estimates of 84.0 percent and 81.4 percent, respectively. As compared with tamoxifen, letrozole significantly reduced the risk of an event ending a period of disease-free survival (hazard ratio, 0.81; 95 percent confidence interval, 0.70 to 0.93; P=0.003), especially the risk of distant recurrence (hazard ratio, 0.73; 95 percent confidence interval, 0.60 to 0.88; P=0.001). Thromboembolism, endometrial cancer, and vaginal bleeding were more common in the tamoxifen group. Women given letrozole had a higher incidence of skeletal and cardiac events and of hypercholesterolemia. In postmenopausal women with endocrine-responsive breast cancer, adjuvant treatment with letrozole, as compared with tamoxifen, reduced the risk of recurrent disease, especially at distant sites. (ClinicalTrials.gov number, NCT00004205.) Copyright 2005 Massachusetts Medical Society.
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              The Malmo Diet and Cancer Study. Design and feasibility.

              The Malmö Diet and Cancer study is a 10-year prospective case-control study in 45-64-year-old men and women (n = 53,000) living in a city with 230,000 inhabitants. One objective is to clarify whether a western diet is associated with certain forms of cancer whilst taking other life-style factors into account. Another broad question is whether oxidative stress and the activity in DNA-repairing systems influence the impact of diet on the development of all or certain forms of cancer. The study is also to act as a resource available for testing new hypotheses emanating from other studies. Initially food intake, heredity, socio-economic factors, life-style pattern, occupational situation, previous and current diseases, symptoms and medications, will be determined. Viable lymphocytes, granulocytes, erythrocytes, and plasma/serum will be stored in a biological bank together with tumour specimens gathered from cases. The incidence and mortality of all cancer forms will then be followed for 10 years by existing registries. Data from the initial examination in these cases will then be compared with those of control subjects not having developed any form of cancer. A biomarker programme, utilizing the biological bank, has been developed and is aimed at finding predictors and/or precursors of cancer. A high participation rate (> 70%) and a high quality biological bank are prerequisites for a successful project. The experience gathered so far indicates that these goals are feasible.
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                Author and article information

                Journal
                Breast Cancer Res
                Breast Cancer Research : BCR
                BioMed Central
                1465-5411
                1465-542X
                2011
                31 January 2011
                : 13
                : 1
                : R12
                Affiliations
                [1 ]UCD School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
                [2 ]Department of Oncology, Clinical Sciences, Lund University, Skåne University Hospital, 221 85 Lund, Sweden
                [3 ]Department of Biotechnology, AlbaNova University Center, Royal Institute of Technology, 106 91 Stockholm, Sweden
                [4 ]Department of Genetics and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
                [5 ]Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
                [6 ]Department of Surgery, Clinical Sciences, Lund University, Skåne University Hospital, 221 85 Lund, Sweden
                [7 ]Department of Pathology, Clinical Sciences, Lund University, Skåne University Hospital, 221 85 Lund, Sweden
                Article
                bcr2820
                10.1186/bcr2820
                3109580
                21281480
                daae6d70-6fda-420e-ab11-b2c7a6bfda2e
                Copyright ©2011 Brennan et al.; licensee BioMed Central Ltd.

                This is an open access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 27 September 2010
                : 2 December 2010
                : 31 January 2011
                Categories
                Research Article

                Oncology & Radiotherapy
                Oncology & Radiotherapy

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