One subtype was associated with the worst outcome; this subtype "shows an epidermal growth factor pathway activation signal, and that's potentially important because there are many new drugs in the clinic today that target that pathway," Perou said.

Another subtype was associated with a "tobacco exposure signature," showing a high expression of genes involved in response to tobacco. Nearly all tumor samples in this subtype came from smokers.

"Another research group did a microarray study comparing airway epithelial samples from smokers versus nonsmokers and said that these genes were high in the smokers and low in the nonsmokers," Perou said.

"And we picked up that exact same set of genes in our study, a validation of what both groups have found."

The study also found tumor molecular biology that differentiated patients with lymph node metastasis from those without metastasis.

"We can see a signature in tumor cells that indicate they are likely to metastasize and the converse, that they are less likely to do so," Perou said.

"This is preliminary data. It must go through rigorous testing and validation before it can change treatment," he added.

"Gene arrays are already providing valuable and useful biological and clinical information and in a handful of years will probably become diagnostic tools in addition to the spectacular biology tools they already are."

Lead author of this study was Dr. Christine H. Chung, a former medical fellow at UNC, now a medical oncologist at Vanderbilt University.

Support for the research came from UNC Lineberger Comprehensive Cancer Center and from the National Cancer Institute.

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