DNA microarrays: a new diagnostic tool and its implications in colorectal cancer.

Effective treatment of colorectal cancer requires early detection and diagnostic and prognostic accuracy in characterizing patients of various risk groups. The development of DNA microarray makes it possible to analyze thousands of genes in a single tissue sample in one experiment and to characterize the biological behavior of colorectal cancer cells. Different cluster algorithms have been used to analyze large datasets on gene expression data, and initial results show significant differences between colorectal cancer and normal colon tissue. Although more than 6000 genes have been analyzed between colorectal cancer and normal tissue, different expression levels have been found in only 100-500 transcripts depending on the cluster algorithm. Most transcripts belong to genes involved in cell growth regulation, differentiation of cells, ribosomal proteins or metalloproteinase. A future goal in microarray technology will be the development of clustered gene chips which characterize each tumor type specifically and focus on gene expression that specifies cell identity.