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Genomic Patterns Reveal Breast Cancer Risks
By Donna Bernstein

Using genome analysis, researchers have discovered distinct patterns in breast cancer tumors that can differentiate those tumors that are likely to spread to the lymph nodes, or to recur from those that are not.

This technique could play an important role in medical decisions about therapy. Someone whose tumor shows a genomic pattern associated with the spread or recurrence of cancer could receive more aggressive treatments, for instance.

Detail of image showing different gene expression patterns. View full

If these tests can be developed to near 100 percent accuracy, patients with a more benign genomic profile could be spared chemotherapy or invasive surgeries that can cause complications or serious side effects.

“Our techniques allow us to start treating patients more appropriately,” says Erich Huang of Duke University Medical Center in Durham North Carolina. The study was a joint project between Duke and the Koo Foundaton Sun Yat-Sen Cancer Centre in Taipei.

Doctors currently make treatment decisions by categorizing women in low-risk or high-risk groups based the type of tumor and whether their lymph nodes are involved. This method is imperfect and misses up to a third of the high-risk patients. Identifying these women through genomic profiling techniques allows for appropriate therapies that could save lives.

The researchers achieved a 90 percent accuracy rate for their predictions based on the activity, or expression, of certain genes.

They used “gene chip” technology to profile the expression of thousands of genes in tumors that had spread to the lymph nodes or recurred. By measuring the interactions of clusters of 50 to 100 highly active genes, they identified distinct patterns of activity that distinguished these more deadly tumors.

This type of genomic analysis could augment clinical staging in the future. But extreme precision is essential, especially when it comes to determining which patients do not need aggressive treatment.

“It is one thing to recommend more aggressive therapy to a woman because of information gleaned from genomic analysis, but withholding treatment demands the highest degree of accuracy,” says Huang.

Gene expression patterns can reveal clues about a tumor’s underlying biology. One unexpected finding of this study was that genes with immune function were expressed highly in tumors that spread to the lymph nodes. This suggests new pathways to consider in the study of how cancer spreads.

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Huang, E. et al. Gene expression predictors of breast cancer outcomes. Lancet 361, 1590-1596 (May 10, 2003).

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