New blood test can detect genes that drive cancer and help to determine best treatment

BMJ 2013; 346 doi: (Published 01 May 2013) Cite this as: BMJ 2013;346:f2825
  1. Zosia Kmietowicz
  1. 1BMJ

Researchers have developed a new blood test that they say could be used to identify women whose breast cancer was being driven by the HER2 gene and who could benefit from treatment with trastuzumab (Herceptin) and similar drugs. They believe that the test could be adapted to a range of other cancers and drug targets.

At the moment women whose breast cancer relapses after initial treatment need to have a biopsy to determine which treatments the cancer is most likely to respond to. But cancers can acquire and lose genes over time, and because biopsies cannot be repeated too often the genes driving their growth can be missed.

The new blood test, dubbed “liquid biopsy,” builds on previous research showing that patients’ blood samples contained trace amounts of DNA from their tumour cells. Researchers at the Institute of Cancer Research in London and the Royal Marsden NHS Foundation Trust took this one step further and investigated whether analysing circulating free DNA could detect gene amplifications known to cause cancer growth.

They did this by taking blood samples from 58 women with recurrent breast cancer and used digital polymerase chain reaction techniques to detect HER2 amplification. The test was able to accurately identify HER2 positive breast cancer 64% of the time and HER2 negative cancer 94% of the time.1

Nicholas Turner, a clinical researcher at the Institute of Cancer Research and honorary consultant oncologist at the Royal Marsden, said, “Herceptin has been effective at treating HER2 positive breast cancers, but the problem with cancer causing genes like HER2 is that they can be acquired or lost as a tumour progresses, so at any point in time you might miss a tumour for which Herceptin may work.

“It’s not possible to take multiple biopsies from patients through their treatment course, but this study shows that we can detect HER2 positive breast cancers through a blood sample. That could allow us to regularly monitor women with breast cancer, using simple blood tests, and potentially increase the number who are treated with Herceptin. The test is at this time at an early stage and does require further assessment in clinical trials before it could become widely available.”

Alan Ashworth, chief executive of the Institute of Cancer Research, said, “Personalised cancer treatments are becoming highly sophisticated and tailored to individual cancers, so it’s really important that doctors can make accurate assessments of the genetic make-up of tumours.

“This new liquid biopsy has exciting potential as a means of analysing tumour DNA in the bloodstream, allowing clinicians to track genetic changes as they happen and adjust treatment to them. By assessing quickly and painlessly whether a particular gene is activated in breast cancer, doctors will be able to choose the best targeted therapy for their patients.”


Cite this as: BMJ 2013;346:f2825