Genes Predict Breast Cancer's Response to Chemo

Doctors can predict how breast cancer patients will respond to chemotherapy by testing for the activity of certain genes, according to a new study published in the August 5, 2005, issue of the Journal of Translational Medicine.

Researchers analyzed samples of breast tissue from five healthy individuals and tumor tissue expressed from 56 breast cancer patients treated with preoperative systemic chemotherapy (PST) consisting of a combination of the anticancer drugs epirubicin and cyclophosphamide. The genes present in the samples were analyzed by a DNA microarray. From this analysis, the authors were able to identify a total of 57 predictor genes active in tumors: 31 associated with a favorable response and 26 associated with a poor response.

The researchers then tested the ability of these genes to predict the response of 27 breast cancer patients treated with PST. The predictor genes were able to correctly predict the outcome of PST in all cases of partial remission and nearly 75% of cases of complete remission of primary tumors. The authors state that this ability to predict patient outcomes will be a "powerful tool” in the treatment of breast cancer.

The research was conducted by Olga Modlich and colleagues from the University of Dusseldorf (Germany) and Bayer AG (Leverkusen, Germany). Currently, most decisions about whether to use chemotherapy as a breast cancer treatment are based on factors such as a patient's age and type of tumor, which are not sufficient to tailor treatment to an individual patient.

A large number of breast cancer patients receive standard chemotherapy treatment despite a poor response to therapy, adverse side effects, or excess healthcare costs. Predicting outcomes will not only help those patients who will respond well but also those who will have a poor response and can be spared treatment. According to the authors, "the identification of molecular markers predictive of patients' responsiveness to treatment is becoming a central focus of research.”





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