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Genetic testing for breast cancer could spare patients needless suffering

This article first appeared in the St. Louis Beacon, Feb. 26, 2009 - As Washington University professor of medicine Matthew Ellis sees it, breast cancer patients fall into three categories: those who are treated accurately; those who respond well to scattershot treatment even though some drugs they received didn't target their specific health needs; and "those who suffer needlessly because of treatments that aren't right for them -- an unfortunately common scenario."

It's the third group Ellis has in mind as he works on ways to improve the effectiveness of breast cancer treatments by further personalizing them.

Breast cancer is caused by genetic abnormalities in breast tissue, but not all forms of the cancer have identical genetic alterations. After analyzing patterns of genetic activity of more than 1,000 breast tumors as part of a study, Ellis and medical colleagues narrowed the thousands of distinguishing genetic differences to a set of 50 genes that they say can be used to reliably identify the four known types of breast cancer.

The study, an advanced version of which was released earlier this month, indicates that by using this 50-gene set, oncologists will have the potential to predict the effective therapy for each breast tumor type.

Breast cancer patients receive a "cocktail of drugs" as part of their treatment, yet many prove ineffective because they are targeting the wrong type of the disease, explains Ellis, a breast cancer specialist at the Siteman Cancer Center at Barnes-Jewish Hospital and the Washington University School of Medicine.

Franklin Salisbury Jr. agrees. He is president of the National Foundation for Cancer Research, which funds scientists' research projects. "Drugs target cancer that expresses a certain gene," Salisbury said. "If a woman's breast cancer doesn't express that gene, even though that drug is for breast cancer, it won't work."

Salisbury said several genetic tests help women learn what molecules are expressed in their tumor. Ellis' test, called Breast Bioclassifier, is an example of one that looks for known biomarkers. Importantly, it is broadly applicable for all women diagnosed with breast cancer.

"What we're talking about is a whole new era of medicine," Salisbury said. "Cancer right now is too often referred to by the symptom, what it looks like, where it is. Cancer is a genetic phenomenon, and there's a new generation of targeted cancer therapies."

Researchers in the new study found that their genetic test is highly sensitive and predictive of how breast cancer patients respond to standard chemotherapy. Of the roughly 180,000 people who are diagnosed with breast cancer every year, Ellis estimates that his test might save roughly one-third of them from undergoing unnecessary chemotherapy.

"The idea is that this would eventually replace some aspects of standard pathology and single-gene testing," Ellis said.

Researchers are investigating how each tumor type responds to breast cancer drugs to help determine the best treatment for patients. They plan to study tumor samples from breast cancer cases dating back a decade or longer. Because patients in these cases have already undergone treatment, the researchers can quickly determine how well various therapies worked for each breast cancer type. Ellis said computational biology allows researchers to weigh the value of each gene in a complex data set.

He said the new genomic test is the first to incorporate a molecular profile for the basal-like type breast cancers, which are arguably the most aggressive but for which there is known targeted therapy. Identifying this particular type of cancer will promote its adequate treatment.

Ellis said patients using the test would have their genetic results as soon as the next day. And he suspects the test would lower the overall cost of medical care for many breast cancer patients. Typically these genetic tests cost from $1,000 to $3,000, which Ellis said he considers "reasonable" given the potential savings on health care for patients who receive proper treatments.

Ellis is one of the inventors of the test and holds patents for technology it employs. Pending U.S. Food and Drug Administration approval, the test will be available this year, starting at a laboratory in Utah, and distributed through a company co-owned by Washington University and two other institutions.

Ellis collaborated on this study, part of a grant from the National Institutes of Health, with researchers from the University of North Carolina at Chapel Hill, University of Utah and University of British Columbia. The full report will appear in the Journal of Clinical Oncology .

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