In the present study peripheral venous blood samples will be obtained before the start of surgery, at the end of surgery, on the first day after and on day 7 after surgery through a central venous catheter. Tumour tissue samples and random liver tru-cut biopsies will be obtained intra-operatively. Real-time quantitative RT-PCR technique (TaqManR), based on 3 different target markers (CEA, CK20 and EpCAM mRNA transcripts) and beta-glucuronidase (GUS) as control gene, will be used to detect and quantify circulating cancer cells in the blood stream. Normalized copy numbers (NCN) will be determined in each sample (analyzed in duplicate). RNA extraction from all samples will be performed using RNeasy mini kit(Qiagen, BD Company). Sample preparation, cDNA synthesis and PCR will be performed in separated rooms in order to prevent cross-contamination.