Researchers from Washington University School of Medicine in St. Louis discovered 18 gene mutations that may influence how certain breast cancer patients respond to specific treatments. These results may inform the pharmaceutical marketing of drugs such as aromatase inhibitors.
About 227,000 women and 2,200 men are projected to develop breast cancer in the U.S. during 2012, according to the National Cancer Institute. The most common form of this malignancy is estrogen-receptor-positive breast cancer. Tumors in this disease grow in response to estrogen. However, aromatase inhibitors block this mechanism, allowing doctors to shrink the tumors to the point where they can perform surgical procedures that preserve most of the breast in female patients.
However, these drugs are not equally effective in all women.
In order to investigate further, a team of scientists compared DNA samples from the tumors of 77 post-menopausal breast cancer patients to samples collected from the healthy cells of the same individuals. This information was combined with data on who responded to a four-month course of aromatase inhibitors.
Results showed that women who were more responsive to the medications tended to have a lower rate of mutations than the patients who were not successful with this regimen. Some 18 mutations appeared to be more influential, leading the scientists to explore their effects in 240 additional women who had breast cancer.
Mutations that were associated with a lower response rate to aromatase inhibitors included alterations of the genes TP53 and MALAT1. Meanwhile, MAP3K1, MAP2K4 and GATA3 were linked to good response rates.
"This is one of the first cancer genomics studies to move beyond cataloging mutations involved in cancer to finding those linked to treatment response and other clinical features," said researcher Elaine Mardis, Ph.D.
Further, larger studies are needed to verify these findings, which are published in the journal Nature.