Genetic Test Measures Toughness of Breast Cancer
Screen could spare many women unnecessary chemotherapy
WEDNESDAY, Dec. 11, 2002 (HealthDayNews) -- Duke Comprehensive Cancer Center researchers are leading a national clinical trial of a new genetic test that can identify drug resistance in breast cancer tumors.
The technique, called gene expression profiling, subtypes each breast cancer tumor by its genetic defects, letting doctors tailor treatment to specific tumors. That could spare millions of women from receiving unnecessary chemotherapy.
Currently, there is no predictive model to help doctors determine which women with breast cancer will or will not respond to hormonal therapies. So, chemotherapy is prescribed as a backup measure against the cancer.
It's estimated that up to 50 percent of women with breast cancer needlessly receive chemotherapy.
The new gene expression profiling technique uses a commercially available gene chip to create a genetic "fingerprint" of a tumor. This information lets doctors categorize each tumor by its genetic defects, and to predict whether standard hormonal therapies alone will work against the tumor or whether chemotherapy will also be necessary.
The study design will be presented at the 25th annual San Antonio Breast Cancer Symposium this week. The national multi-center study will include 140 women.
Researchers will take samples of the women's breast cancer tumors. They will then receive the estrogen-depriving drug letrozole before they have surgery. Letrozole reduces production of estrogen, which fuels the growth of up to 80 percent of all breast cancers.
However, some tumors don't respond to hormonal therapies and some tumors that initially respond to hormonal therapies later become resistant.
To better understand that, the researchers will use gene expression profiling to measure changes in 16,000 genes as they respond or don't respond to letrozole.
The National Cancer Institute has more about breast cancer treatments.