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ISRN Oncology
Volume 2013 (2013), Article ID 924971, 12 pages
http://dx.doi.org/10.1155/2013/924971
Research Article

Gene Expression Profile Analysis of T1 and T2 Breast Cancer Reveals Different Activation Pathways

1Department of Surgery, Akershus University Hospital, 1478 Lørenskog, Norway
2Institute for Clinical Medicine, Faculty of Medicine, University of Oslo, 0318 Oslo, Norway
3Department of Radiology, School of Medicine, Stanford Center for Cancer Systems Biology, Stanford University, Stanford, CA 94305-5488, USA
4Department of Genetics, Institute for Cancer Research, Oslo University Hospital Radiumhospitalet, 0310 Oslo, Norway
5Department of Clinical Molecular Biology and Laboratory Sciences (EpiGen), Akershus University Hospital, 1478 Lørenskog, Norway
6Department of Pathology, Akershus University Hospital, 1478 Lørenskog, Norway
7Institute of Health Promotion, Akershus University Hospital, 1478 Lørenskog, Norway

Received 29 November 2012; Accepted 8 January 2013

Academic Editors: A. Abdollahi, Y. Ionov, and V. Lorusso

Copyright © 2013 Margit L. H. Riis et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Breast cancers today are of predominantly T1 (  cm) or T2 (  cm) categories due to early diagnosis. Molecular profiling using microarrays has led to the notion of breast cancer as a heterogeneous disease both clinically and molecularly. Given the prognostic power and clinical use of tumor size, the purpose of this study was to search for molecular signatures characterizing clinical T1 and T2. In total 46 samples were included in the discovery dataset. After adjusting for hormone receptor status, lymph node status, grade, and tumor subclass 441 genes were differently expressed between T1 and T2 tumors. Focal adhesion and extracellular matrix receptor interaction were upregulated in the smaller tumors while p38MAPK signaling and immune-related pathways were more dominant in the larger tumors. The T-size signature was then tested on a validation set of 947 breast tumor samples. Using the T-size expression signatures instead of tumor size leads to a significant difference in risk for distant metastases ( ). If further confirmed, this molecular signature can be used to select patients with tumor category T1 who may need more aggressive treatment and patients with tumor category T2 who may have less benefit from it.