Using novel DNA array technology, the study identified differences in the gene patterns from tumor samples that predict which patients would respond to treatment with the chemotherapy docetaxel, marketed under the brand name Taxotere by Aventis.
After studying pretreatment biopsies from 24 patients and their genes after treatment, results show that tumors responding to Taxotere show a different pattern than tumors that had not responded to drug therapy. In the study, 88 percent of the genes were correctly classified, said Dr. Jenny Chang, an assistant professor of medicine at Baylor. This study marks the first time microarray technology has been used to study breast cancer tumor response to a chemotherapeutic agent.
"We may have a clinically useful predictive test for chemotherapy sensitivity that may allow us to prioritize breast cancer treatment strategies based on their likelihood of success," said Chang. "This research, if validated, may lead to important advances in the treatment of breast cancer including reducing unnecessary treatment for some women, while optimizing therapy for others."
The team of investigators, led by Chang, studied thousands of genes with new DNA array technology, to find the differences between tumors that responded to Taxotere chemotherapy and those tumors that failed to respond. This finding confirmed that breast cancers are not all alike, and treatment can be tailored to individual tumors.
"We are trying not only to understand the disease, but also how a patient's tumor may respond to a treatment even before we select a chemotherapy. As opposed to acquired resistance, which builds up with months of therapy, these results show that some women will be resistant to the drug from day one," Chang said. "Once confirmed in a larger study, this type of molecular profiling could have profound clinical applications in defining optimal treatment selection for each individual patient."
Chemotherapy, designed to eliminate cancer cells that have spread, is beneficial in reducing the risk of death in many patients with early breast cancer, but physicians have long had trouble figuring out which patients would benefit from the treatment, she said. As a result, some breast cancer patients needlessly receive chemotherapy after surgery. Chemotherapy can have serious side effects, including nausea, vomiting, hair loss, diarrhea, nerve damage and infections.