Oligonucleotide microarray analysis of mRNA extracted from the primary pancreatic tumor and from disseminated cancer cells before, during and the day after surgery. The focus of this study is not to identify specific markers for diagnosis or for drug targets but to find indications of metastasis through the study of gene expression in cancer cells circulating in the bloodstream. Our main objective is to analyze expression profiles of circulating pancreatic cancer cells. Changes will be analyzed in the expression of genes representative of several different pathways frequently altered during the progression of cancer such as tumor suppressors, oncogenes, signal transduction molecules, growth factors and angiogenesis factors. Gene expression profile data will be obtained on apoptosis, cell cycle, cell growth and differentiation, cell migration and motility, signal transduction and other cancer-related genes. Latest developments in microarray technology comprise the manufacturing of the complete genome and in designing new amplification strategies to be able to analyze very small samples less than 1 ng total RNA (Xiang CC, Chen M, Kozhich OA, Phan QN, Inman JM, Chen Y, Brownstein MJ. Probe generation directly from small number of cells for DNA microarray studies. Biotechniques 2003; 34: 386-8, 390, 392-3. Schindler H, Wiese A, Auer J, Burtscher H. cRNA target preparation for microarrays: comparison of gene expression profiles generated with different amplification procedures. Anal Biochem 2005; 344: 92-101. Puskás LG, Zvara Á, Hackler L Jr, Van Hummelen P. RNA amplification results in reproducible microarray data with slight ratio bias. Biotechniques 2002; 32: 1330-1341). In the present study the number of cancer cells circulating in the blood stream is expected to be extremely small. Therefore, linear RNA amplification (T7 RNA-polymerase) is used in order to generate enough material for labeling and hybridization on the arrays. Two rounds of amplification are performed routinely. This has been performed successfully and reproducibly starting from as little as 700 cells isolated via Laser Capture Microdissection (data unpublished).