Patient's Genes Can Predict Response To Chemotherapy For Breast Cancer

Olga Modlichand colleagues, from the University of Düsseldorf and Bayer HealthCareAG in Germany, analysed samples of breast tissue from five healthyindividuals and tumour tissue from fifty-six breast cancer patientstreated with preoperative systemic chemotherapy (PST) with acombination of the anti-cancer drugs epirubicin and cyclophosphamide.The genes present in the samples were analysed using a DNA microarray -a collection of microscopic DNA spots attached to a solid surface usedto measure the expression levels of large numbers of genessimultaneously.

From the DNA microarray analysis the authors wereable to identify a total of fifty-seven 'predictor' genes active intumours: thirty-one genes associated with a favourable response andtwenty-six genes associated with a poor response. The authors thentested the ability of these genes to predict the response oftwenty-seven breast cancer patients, who were then treated with PST.

Thepredictor genes could be used to correctly predict the outcome of PSTin all cases of partial remission and nearly 75% of cases of completeremission of primary tumours. According to the authors the use ofmicroarray technology to identify genes that can predict response tochemotherapy could represent a powerful tool to identify patients forwhom PST is the most appropriate, and would be the most successful formof treatment.

Currently, decisions about whether to usechemotherapy as a breast cancer treatment are based on factors such aspatients' age and type and size of tumour. These factors do not providesufficient information to tailor treatment to the individual patient.Nearly all breast cancer patients receive standard chemotherapytreatment, despite the potential for a poor response to therapy,adverse side effects and excess healthcare costs. According to theauthors "the identification of molecular markers predictive ofpatients' responsiveness to treatment is becoming a central focus ofresearch". The ability to predict a patient's response to chemotherapyfor breast cancer would be of benefit to doctors and patients, shiftingthe focus away from a standard treatment for all patients and towardstreatment based on predictions made from patients' genetic background.