Genes linked to colon cancer take sides

From Washington, D.C., at a meeting of the American Association for Cancer Research

Cancers on opposite ends of the colon are genetically distinct, researchers from Denmark and Finland have found. The standard practice of treating them as the same disease could explain why some people with colon cancer respond better to certain treatments than others do, says Sanne H. Olesen of rhus University Hospital in Denmark.

The colon forms an inverted U between the small intestine and the rectum. Some studies have suggested that colon cancers develop differently, depending on whether they originate in the organ’s right or left side. In general, right-side colon cancers are less aggressive and less deadly.

To explore these differences, Olesen and her colleagues compiled profiles of gene activity in both portions of cancer patients’ colons.

Using samples of healthy and cancerous tissue from both sides of the colon, the researchers established the pattern of activity for 6,800 genes. Compared with healthy tissue, cancerous tissue from the left colon exhibited telltale differences in the activity of 186 of the genes, the researchers found. The number of gene-activity differences for the right-colon cancer was 118.

Only 30 of the differences in gene expression that distinguished cancer cells from healthy ones were common to cancers from both sides of the organ, Olesen reports. Therefore, she and her colleagues suggest, gene-based therapies and diagnostic tests for colon cancer should focus on those 30 genes.

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