Developing liquid biopsies to detect early signs of lung cancer

Every year, around 46,700 people are diagnosed with lung cancer in the UK alone. Sadly, only 1 in 20 will survive for 10 years or more – a number that has not improved in the past decade. One of the reasons for such poor survival is that lung cancer is often diagnosed late when it has already spread, so there is a clear and urgent need to detect this cancer sooner.

At the forefront of this effort is Professor Caroline Dive, who is based at the CRUK Manchester Institute and regarded as one of the leading authorities on monitoring cancer using patients’ blood. To do this, she looks at ‘circulating tumour cells’ (CTCs), specifically in the context of lung cancer. CTCs are cells that have broken away from the tumour and entered the bloodstream, which could be detected using a simple blood test.

This approach – known as a ‘liquid biopsy’ – also has the potential to provide doctors with a simpler and less invasive way to monitor a patient’s treatment. As we know, cancer can become resistant to treatment over time, but traditionally the only way to monitor this is via repeated solid tumour biopsies, which may not even be possible as the disease progresses or where tumours are in difficult-to-reach places, such as the lung. Liquid biopsies would provide doctors with regular updates on the molecular profile of the patient’s tumour, allowing them to monitor the effectiveness of new treatments and switch treatments earlier if the tumour shows signs of resistance. Following treatment, they could also show doctors how likely it is for their cancer to come back.

The biggest challenge in the development of this technique is that although cancer cells are very different to normal cells, it’s difficult to spot them in the blood. In a millilitre of blood, there are only around 200 tumour cells compared to around five billion healthy red blood cells. The test must be sensitive enough to detect the cancer cells and accurate enough to ensure healthy blood cells are not misdiagnosed as CTCs, as this could interfere with the results.

If it’s successful, this simple, precise and non-invasive way of tracking tumour cells has the power to completely change the way we treat and manage lung cancer, one of the hardest cancers to treat.