Cancerous tumours can shed cells that travel through the blood stream and create new cancerous growths. These seed cells can be very difficult to detect, but Stanford scientists are developing a non-invasive method using a mini-microscope that could find these cells.
The rule of thumb with cancer is that the earlier you can detect the disease, the more effective the treatment, and hence improve potential outcomes.
Currently, doctors draw a patient's blood and analyse it using special antibodies to detect the presence of the seeds, called circulating tumour cells (CTCs). This works well if CTCs are present in large numbers, but may fail to detect smaller numbers released by earlier tumours.
Now, a team of engineers, scientists and doctors from Stanford is developing a mini-microscope that might be able to non-invasively detect the CTCs earlier than ever, allowing for earlier interventions.
"There has been a huge push to increase sensitivity," said Bonnie King, an instructor at Stanford School of Medicine. "We suspect that CTCs often circulate in numbers below our current threshold of detectability."
A major advantage with the microscopic technique, King said, is the ability to screen much larger volumes of blood, rather than just a small vial collected from a patient. This will be done using a method called in vivo flow cytometry – a laser-based technology for counting cells in a live subject.
The process would involve a doctor injecting a patient with a dye that causes the CTCs to fluoresce. The doctor would then use the pen-size microscope to focus a low-power laser light on a blood vessel just a few hair-widths below the patient's skin.
As the dyed cancer cells pass through the laser, the light excites them and causes them to stand out from normal cells. The microscope registers each of these cells and a computer logs each observation. The improved sensitivity of the technology and the ability to non-invasively scan blood for long periods will help create a fuller picture of the number of CTCs in a person's body.
To date, the blood-scan group has focused on developing the method in mice, taking advantage of the thin transparent tissue of the ear to image fluorescent cells traversing the small blood vessels below the skin.
Soon the researchers will move the microscope to a clinical setting to conduct a proof-of-principle test of the technique in humans.
Geoffrey Gurtner, a professor of surgery at Stanford, is currently conducting a clinical trial to evaluate an FDA-approved green dye for defining skin vasculature during post-mastectomy breast reconstruction surgeries. The researchers are piggybacking on this trial to test the miniature microscope's ability to detect blood vessels and circulating cells.