Gene may determine efficacy of cancer drug

A new study, published in The Lancet, shows that it may be possible to determine whether breast cancer patients will respond to cancer treatment by performing a genetic test on them. Establishing if a woman will or will not respond to a particular drug could save many women from undergoing unnecessary chemotherapy, in turn saving the National Health Service millions of pounds.

According to the authors of the study, about half of breast cancer patients treated with chemotherapy obtain no benefit, while still suffering from the side effects of the drugs. The researchers, led by Jenny Chang from Baylor College of Medicine in Texas, US, studied the gene expression profiles of women with breast cancer and their responses to chemotherapy with the drug docetaxel. They took tissue samples from the breast tumours of 24 women of varying ages, who had been diagnosed for the first time as having breast cancer. The women were then all treated with docetaxel, which is used to shrink tumours before surgery, and is the most commonly used breast cancer drug in the UK.

After the treatment, the researchers found that 11 of the 24 tumours had shrunk more than 75 per cent, but 13 were 'resistant', meaning they showed shrinkage of less than 75 per cent. The results were compared to the gene expression data that had been collated from the tissue samples. Those women whose tumours were not resistant showed higher levels of expression in genes involved in the cell cycle, protein transport and protein modification.

The research indicates that in the future it may be possible to predict the effectiveness of particular drugs on particular patients. But, said James Brenton, of Cambridge University, UK, who wrote a commentary accompanying the Lancet research, 'we should be very cautious about this research because the data sample is very small'. But, he said, this study 'is the first of many'.