Microarray technology could help predict patient response to adjuvant therapy for breast cancer

Microarray technology could be used to tailor therapy according to the individual, and prevent breast cancer patients from having to undergo painful unsuccessful therapies. In a study published in the journal Breast Cancer Research, researchers analysed tumour tissue samples and identified a group of 64 genes that can be used to predict a patient’s response in the five years after adjuvant therapy for breast cancer. Identifying patients whose breast tumours express these genes could potentially be used to predict which patients would not benefit from adjuvant therapy, and avoid patients being given therapies with the potential of causing more harm than good.

A team of researchers led by Jonas Bergh from the Karolinska Institutet in Stockholm, Sweden, analysed the gene expression profiles of 159 breast cancer patients using DNA microarray analysis. From these samples they identified the genetic signatures shown by 38 patients who had a poor prognosis – defined as relapse or death from any cause within 5 years. The remaining 121 patients were defined as the ’good prognosis’ group. The researchers also used gene expression profiling to separate patients who did well with and without adjuvant therapy, and those whose tumours failed to respond to treatment.

An analysis of the genes expressed in the tumours of all 159 patients showed that 64 genes were used to separate the patients with good and poor prognoses. The researchers then tested the predictive value of the group of 64 genes compared with three currently used clinical markers. Using the expression patterns of the 64 genes identified by the researchers gave significantly better (P=0.007) prediction rates than histological grading, tumour stage and age – which are all accepted prognostic markers for breast cancer.

The present lack of criteria to help tailor breast cancer treatment to individual patients indicates a need to develop new techniques for better prediction of how patients will respond to adjuvant treatments. The researchers suggest that the technique of DNA microarray analysis could be developed to help breast cancer patients who do not benefit from adjuvant therapy, and avoid painful unnecessary treatments and wastage of healthcare resources.