Tumour stroma gene expression in biopsy specimens may obscure the expression of tumour parenchyma, hampering the predictive power of microarrays. We aimed to assess the utility of fluorescence-activated cell sorting (FACS) for generating cell populations for gene expression analysis and to compare the gene expression of FACS-purified tumour parenchyma to that of whole tumour biopsies. Single cell suspensions were generated from colorectal tumour biopsies and tumour parenchyma was separated using FACS. Fluorescence-activated cell sorting allowed reliable estimation and purification of cell populations, generating parenchymal purity above 90%. RNA from FACS-purified and corresponding whole tumour biopsies was hybridised to Affymetrix oligonucleotide microarrays. Whole tumour and parenchymal samples demonstrated differential gene expression, with 289 genes significantly overexpressed in the whole tumour, many of which were consistent with stromal gene expression (e.g., COL6A3, COL1A2, POSTN, TIMP2). Genes characteristic of colorectal carcinoma were overexpressed in the FACS-purified cells (e.g., HOX2D and RHOB). We found FACS to be a robust method for generating samples for gene expression analysis, allowing simultaneous assessment of parenchymal and stromal compartments. Gross stromal contamination may affect the interpretation of cancer gene expression microarray experiments, with implications for hypotheses generation and the stability of expression signatures used for predicting clinical outcomes.
Our aim was to assess the long-term survival advantage associated with the laparoscopic approach for colon cancer resection in an Irish minimally invasive unit. Between January 2005 and December 2006, 154 patients underwent resection for colon cancer. 108 underwent a laparoscopic resection, with a conversion rate of 11%. The overall 5 year survival was 71.4%. The overall 5 year survival rate for laparoscopic resections was 80.6% where as the overall survival for open resection was 50%. Laparoscopic surgery had a significant 5 year overall survival advantage compared to open in both non metastatic disease (Stage I and II) (92.2% vs. 69.6%, p = 0.0288) and metastatic disease (Stage III and IV), (68.4% vs. 30.4%, p = 0.0026). Laparoscopic surgery in a dedicated minimally invasive unit with verifiable low conversion rates is feasible and in our experience associated with a long-term survival advantage for colon cancer.
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