Genetic test to improve breast cancer treatment

Scientists have developed a way to identify six key genes which, if faulty, can prevent particular chemotherapy drugs from working in patients with breast cancer. The findings bring cancer therapy one step closer to the promise of targeted treatments for patients, based on the genetic characteristics of their tumours.

The study was carried out by an international team of researchers, led by Dr Charles Swanton and colleagues at Cancer Research UK's London Research Institute, and was published in the journal Lancet Oncology.

The researchers studied 829 genes which are involved in the response to paxlitaxel, a drug which stops the growth of cancer cells by halting cell division and which is given to patients to shrink their tumours before surgery. They switched off each of the genes one by one in the cancer cells - using a technique called RNAi (RNA interference) to silence their expression - and found six which were essential for the drug to work properly. They went on to demonstrate that these few genes could be used to identify which patients would benefit the most from the drug.

Paxlitaxel is currently prescribed to approximately 15 per cent of the 45,500 breast cancer sufferers who are diagnosed each year in the UK. However, it can be ineffective and can cause adverse side effects, such as a weakened immune system, nerve pain and hair loss.

Dr Swanton explained that the new research 'shows it is now possible to rapidly pinpoint genes which prevent cancer cells from being destroyed by anti-cancer drugs and use these same genes to predict which patients will benefit from specific types of treatment'.

Further studies are required in order to confirm the accuracy of these tests in patients and to develop a simple diagnostic test which can be used by doctors when deciding which therapy to prescribe.

Dr Swanton said: 'Now the challenge is to apply these methods to other drugs in cancer medicine and to help identify new drugs within clinical trials that might benefit patients who are predicted to be unresponsive to treatments'.

It is thought that some of these may currently be too expensive to fund on the NHS but that, in the future, tailoring drugs to individual patients will result in more effective treatment and will reduce the cost of cancer care. 'This could potentially improve cancer survival in the long term', Dr Swanton added.