Test Predicts Breast Cancer Recurrence
Genetic Tool May Help Breast Cancer Patients Choose the Best Treatment
Dec. 19, 2006 (San Antonio) -- A test that characterizes each breast tumor
by its unique genetic fingerprint may soon allow doctors to identify those
women whose cancer is most likely to
recur despite tamoxifen therapy, Dutch researchers report.
The powerful genetic tool can help spare many women from unnecessary
treatment that is doomed to fail, says researcher Marleen Kok, MD, of the
Netherlands Cancer Institute in Amsterdam.
The test, which looks for the presence of 81 genes involved in tamoxifen
response, was described at the San Antonio Breast Cancer Symposium (SABCS).
Currently, doctors rely on tests that detect levels of hormone receptors to
decide if a woman should get the hormone drug tamoxifen. That's because the
drug tends to benefit women whose cancers are fueled by hormones.
"But those tests don't tell us the whole story," says SABCS
Co-director C. Kent Osborne, MD, head of the cancer center at Baylor College of
Medicine in Houston.
Optimizing Breast Cancer Treatment
For the study, which employed a commercially available gene chip, the
researchers tested and then validated the technique on frozen tissue samples
from more than 60 women with breast cancer who were treated with tamoxifen.
The tissue samples, about one-third the thickness of a sheet of paper, were
sent to a lab for analysis.
"We found that the test correctly classified 84% of nonresponders --
women who progressed despite tamoxifen therapy," Kok says.
The researchers then compared the new test to other predictors of tamoxifen
response, including whether a woman had reached menopause, the
aggressiveness of her cancer, and levels of estrogen receptors and progesterone
They found that the gene test outperformed all the predictors except the
progesterone receptor test. And when the gene test and progesterone receptor
test were used in combination, they got the best results of all.
"Using the two tests together will optimize treatment selection,"
Though it has yet to be tested, the genetic screen will presumably also help
doctors identify women whose cancer is likely to spread despite treatment with
newer hormone drugs called aromatase inhibitors, she says.
That's the next step, according to Kok. "If we know a woman is resistant
to tamoxifen, we can start her on an aromatase inhibitor. If we know she's also
resistant to aromatase inhibitors, we can offer chemotherapy," she
Aromatase inhibitors include Arimidex, Aromasin, and Femara.