Developing ways to improve detection and monitoring of cancer is crucial if more targeted treatments are to be given and survival rates are to increase.
One method of analysing a patient that could lead to improvements is detecting and characterising circulating tumour cells (CTCs) in the blood.
These are cancer cells released by the main tumour that can cause the spread of the disease around the body in a process known as metastasis, which causes nine out of 10 cancer deaths.
Abu Dhabi researcher Dr Anas Alazzam is one of a team who have designed a device that can isolate CTCs from blood samples.
If used clinically, this could give valuable information to doctors about a patient’s disease.
The technique involves a small electrical device that separates out the CTCs and, when development work is more advanced, should also be able to identify what type of cancer the cells represent.
The separation takes place by dielectrophoresis, which relies on electrical differences between cancerous and normal cells.
In a recent paper in Microsystems and Nanoengineering, Dr Alazzam and three co-authors describe the use of the device to separate cancer cells that have been added to blood samples.
“Such a device is extremely important. It’s not only telling if someone has cancer, but after treatment it will tell how the treatment is progressing,” says Dr Alazzam, an assistant professor in the department of mechanical engineering at Khalifa University.
He is keen to emphasise that the device is at an early stage and that its use in hospitals on patients is, at least, several years away.
“I don’t have a device that can cure cancer or detect cancer. It’s not yet at the point where we could apply it for patients,” Dr Alazzam says.
The speed of separation of cells is “very low” and the researchers have yet to work out how to characterise the cells using radio-frequency imaging, which is based on the emission of radio waves, a type of electromagnetic wave with a frequency greater than infra-red waves.
“We have found a difference between cancer cells in terms of their electrical and mechanical properties but we cannot say ‘this is prostate’, or ‘this is breast’,” Dr Alazzam says.
“Now we’re not able to do that, but hopefully in the future we will be able to.”
He has been working on the project since 2008, when he was researching his PhD in Canada.
Dr Alazzam moved to Khalifa University in 2012 and set up a microfabrication centre to produce the tiny microelectromechanical systems, or Mems – devices of the kind used to separate cells.
It was in the 19th century that a scientist first proposed that CTCs could be involved in the spread of cancer around the body but it is only now that scientists are getting to grips with their use in a clinical setting.
A 2010 paper written by Dr Matthew Krebs of the University of Manchester, and other researchers, published in Therapeutic Advances in Medical Oncology, says: “The identification and molecular characterisation of CTCs in cancer patients remains key to unprecedented insights into the metastatic process and is anticipated to unmask novel therapeutic targets.”
Given their potential, it is no wonder that many researchers around the world are looking at CTCs.
Among them is Dr Mark Howarth, an associate professor in the department of biochemistry at the University of Oxford, who is looking at ways to capture CTCs using antibodies.
Dr Howarth identifies two key ways in which detecting and identifying the cells could prove useful: where a person does not have a clearly identified tumour mass; and where they have had surgery to remove a tumour and doctors would like to know whether or not the cancer has been eliminated.
“By looking for these CTCs, you can get an early warning of whether the cancer has come back,” he says.
“Taking these blood samples is something you might do every month or twice a year or something like that.”
Identifying CTCs could also be helpful in indicating what drugs would be effective in treating the cancer.
But like Dr Alazzam, Dr Howarth is keen to stress that the technology is not yet ready for day-to-day use.
In particular, he says that scientists are some way off being able to use CTCs to routinely identify whether a person actually has cancer in the first place, partly because of the risk of “false positives”, where the presence of abnormal cells can suggest that a person has the disease when they do not.
Already available commercially is Cellsearch, a CTC detection technique that involves magnetophoresis, in which cells are separated from one another based on magnetic properties.
This requires them to be labelled magnetically and the technique is viable for use with only a few types of cancer.
By contrast, Dr Alazzam’s work makes use of natural differences in the electrical properties of cells, so no labelling is required, and he says a wider range of cancers could eventually be identified. Cells can also be cultured after separation for further analysis.
“The long-term goal is to create what’s called a point-of-care device,” he says.
“This is the test done on the spot: the patient can provide the blood and the device can tell if they have cancer or not.”
The whole device could be “much smaller than a laptop” when fully developed, Dr Alazzam says.
Before it becomes widely used, improvements are needed in the speed of separation and in the characterisation of cell type, something Dr Alazzam describes as a continuing “research problem”.
“I dream of developing a platform that can detect any malignant cell in a blood sample,” he says.
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