Gene Expression Profiling Predicts Tumor Response to Drugs

A new technique called gene expression profiling subtypes each breast cancer tumor by its genetic defects, enabling doctors to tailor therapy to suit that particular tumor. The technique was presented at the annual Breast Cancer Symposium in San Antonio (TX, USA).

The new technique uses a commercially available gene chip to create a genetic "fingerprint” of each tumor. Doctors use the chip to categorize each tumor by its genetic defects and then predict whether the tumor will respond to standard hormonal therapies or require additional chemotherapy. In a study of the technique, participants will provide biopsies of their breast tumors, then receive the estrogen-depriving drug letrozole, an aromatase inhibitor, before surgery to shrink their cancers. Some tumors expected to respond to hormonal therapies will remain unaffected and some that respond initially will later become resistant.

"Currently, we have no predictive model to determine who will respond to hormonal therapies and who won't, so we prescribe chemotherapy as a backup measure to ensure the cancer's demise,” said Matthew Ellis, M.D., Ph.D., director of the breast cancer program at Duke Comprehensive Cancer Center (Durham, NC, USA). "This one-treatment-fits-all approach leads to a huge amount of over-treatment, with up to 50% of women unnecessarily receiving chemotherapy.”




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