Cancer research UK scientists have found that counting the number of lung cancer cells circulating in the blood could determine how aggressive the cancer is and predict the best treatment to use.

The research, published in the Journal of Clinical Oncology, looked at the number of circulating tumour cells (CTCs) in blood samples of 101 non small cell lung cancer patients before and after one cycle of chemotherapy. They found lung cancer patients with five or more CTCs had a significantly worse survival. The median overall survival was 4.3 months for patients with five or more CTCs compared to 8.1 months for patients with fewer than five.

Chemotherapy and radiotherapy can slow the growth of lung cancer but in most patients the cancer returns and is more resistant to treatment, but there are no tests available that provide early warning about resistance.

Counting CTCs could be a simple way to monitor how well a patient is responding to treatment within a few weeks of starting it. Being able to detect when CTC numbers are rising could give doctors the option to move patients onto new treatments earlier.

Dr Fiona Blackhall, joint author and lung cancer clinician The Christie in Manchester, said: "Our research shows a new way to monitor how a patient's lung cancer is responding to treatment and determine how aggressive it is. We now need to test our findings in more patients but, if our results are confirmed, there is now the potential to tailor treatments to individual patients and find new ways to treat the disease."

Around 50 per cent of patients do not respond to existing treatment but may be exposed to the side effects that accompany some of these treatments.

New drugs are in the pipeline to treat lung cancer, particularly more tailored treatments that are designed to target the genetic faults in lung cancer. But when new drugs are tested in clinical trials it is rarely possible to assess how the treatment is affecting the cancer cells at a molecular level.

Counting CTCs potentially provides a less invasive way to look at the cancer cells before and after a new treatment to see if the drug is working.

Professor Caroline Dive, lead author based at Cancer Research UK's Paterson Institute in Manchester, said: "In the near future we hope to be able to use gene sequencing tools to learn more about CTCs. If we can do this before a patient has chemotherapy and then again later if the cancer returns we may be able to learn more about the processes that lead to drug resistance and ultimately develop new drugs."

Until now, the diagnosis of lung cancer has been made through an invasive procedure called a bronchoscopy where a camera is passed into the airways and a needle passed through to the camera to take a piece of tissue for diagnosis. But, this invasive procedure is normally only done once and it is not possible to look at changes in the cancer over time.

Lung cancer is the second most common cancer in the UK - in 2008 around 41,000 people were diagnosed with the disease. It has one of the lowest survival outcomes of any cancer because over two-thirds of patients are diagnosed at a late stage when curative treatment is not possible. Each year around 35,000 people die from the disease.

Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "Lung cancer is the leading cause of death from cancer in the UK and we desperately need new treatments for the disease. To be able to detect and count these rare tumour cells circulating through the blood, and the link this has to the progress of the disease, opens an incredibly exciting new area of research. We could now look at the genetic faults that are behind the disease and start to develop drugs that target these."

Source: CRUK

Article: Krebs, M. G et al. Evaluation and prognostic significance of circulating tumor cells in patients with non-small- cell lung cancer Journal of Clinical Oncology (2011)