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Researchers from the National Human Genome Research Institute (NHGRI) at the National Institutes of Health (NIH) have developed a new genetic test that enables them to distinguish between hereditary and non-hereditary forms of breast cancer. The new technique, called gene expression profiling, allows physicians to easily determine the type of breast cancer a patient has and develop a suitable treatment plan based on this information. The discovery may also help researchers devise breast cancer prevention strategies using genetic information. The "pioneering" research was conducted by an international team of scientists, led by Dr. Jeffrey Trent, NHGRI's Scientific Director and Head of the NHGRI Cancer Genetics Laboratory. The team performed tests using a type of DNA chip called a microarray to study the activity of thousands of genes within breast cancer cells. By studying the differences in patterns of gene activity, the researchers were able to successfully determine what type of breast cancer was present. Previous research has shown that between 5% and 10% of all breast cancer cases are genetic; these cases arise from mutations of certain genes. Specifically, women who are born with mutated forms of BRCA1 (breast cancer gene 1) or BRCA2 (breast cancer gene 2) have a higher than average risk of developing breast cancer. The remaining 90% to 95% of breast cancer cases are thought to be "sporadic"-caused by genetic changes that occur during a woman’s lifetime. To conduct their research, Dr. Trent and his colleagues studied 22 breast cancer tumors that had been surgically removed from patients. Of the 22 cancers, 15 were already known to be hereditary from previous analyses (7 were caused by BRCA1 gene mutations and 8 were caused by BRCA2 gene mutations). The other 8 were sporadic breast cancers since no family history of breast cancer existed. After performing gene expression profiling using microarray analyses, the researchers were able to correctly differentiate between the BRCA1, BRCA2 and non-hereditary forms of breast cancer. "Our gene expression profiling technology reveals a pattern, a kind of fingerprint for each tumor type," said Dr. Trent in an NIH news release. "The fingerprint shows us key genes involved in tumor development and progression." Dr. Trent and his colleagues believe their research could have important implications for diagnostic and treatment strategies. For example, women who carry BRCA1 or BRCA 2 mutations may be at a higher risk of a breast cancer recurrence than patients with sporadic breast cancer and should be closely monitored by physicians. Also, by better understanding how mutations of BRCA1 and BRCA2 occur, scientists may be able to develop more effective ways to treat hereditary forms of breast cancer and perhaps eventually develop mechanisms for preventing their mutations. "This powerful new technology gives us a snapshot of exactly which genes are active in a tumor cell," said Dr. Trent in an NIH news release. "Over the last few decades, scientists have made important progress in understanding the molecular origins of cancer by studying one gene at a time. Now we can look at thousands, and even tens of thousands of genes as they interact to produce a tumor." In fact, in August 2000, a team of researchers from the NHGRI found evidence of a third gene (in addition to BRCA1 or BRCA2) that may be responsible for hereditary breast cancers in some Nordic families. The researchers hope to use the new gene expression profiling to study these families and perhaps identify other genes involved in breast cancer. According NHGRI Director Dr. Francis Collins, "This work is an excellent example of the kind of research that will characterize the next phase of the Human Genome Project, as scientists move from sequencing the entire human genetic code to understanding the functions of genes in health and disease," said Dr. Collins in an NIH news release. Presently, BRCA genetic testing is available for eligible women at high risk of breast cancer (due to a strong family history, etc.). The decision to undergo genetic testing should be made carefully after considering the advantages and disadvantages of knowing the results. Click here to learn more about BRCA gene testing. All women should follow the American Cancer Society’s guidelines to help detect breast cancer at an early stage, when the chances for successful treatment and survival are the greatest:
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