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Using molecular tools to diagnose cancer


The genetic signatures of tumors may offer physicians a powerful new tool to help identify cancers that elude diagnosis using traditional techniques.

Researchers led by Todd R. Golub, of the Dana-Farber Cancer Institute in Boston, Massachusetts, were able to correctly diagnose cancers in 78 percent of tumor samples by analyzing the expression profiles of tumor genes. Those included 14 common classes of tumors, ranging from breast cancer to melanoma. Their study was published in the Proceedings of the National Academy of Sciences.

Identifying tumor-specific molecular markers. View larger

"Molecular diagnostics offer the promise of precise, objective, and systematic human cancer classification," the researchers write. But they caution that such tests cannot yet be used widely "because characteristic molecular markers for most solid tumors have yet to be identified."

To lay the groundwork for their cancer diagnosis project, the researchers created a gene expression database that included profiles of the tumor samples. They used oligonucleotide microarrays—glass slides spotted with genes of known functions—containing 16,063 genes. Employing two different techniques—"clustering" and "training"—the scientists then analyzed the data and classified the tumors.

The researchers think that analyzing such genetic signatures can be important in troublesome diagnoses because "molecular characteristics of a tumor sample may remain intact despite atypical clinical or histological features." However, they concede that such molecular tools are "not a substitute for traditional diagnostics," such as analyzing tissues and examining patients.

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Ramaswamy, S. et al. Multiclass cancer diagnosis using tumor gene expression signatures. Proc Natl Acad Sci USA 98, 15149-15154 (December 18, 2001).

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