There is a need for blood-based tests in monitoring patients with more advanced melanoma, she said. Doctors can use CT scans to see whether a treatment is working, but those scans can only be done every three months or so, Eroglu explained.
A blood test could be done more often.
“The inherent limitation is the amount of blood you need to draw,” Eroglu said. “This system essentially gets around that.”
However, it’s not yet clear what doctors can do with the finding that a patient has some circulating tumor cells.
Eroglu said future studies could, for instance, follow melanoma patients after they receive treatment. “You could look at how well the detection of circulating tumor cells correlates with patients’ outcomes,” she said.
Other researchers have been working on blood tests that detect bits of DNA from tumor cells, Eroglu noted. There is evidence that among patients who’ve had surgery for earlier-stage melanoma, those with detectable tumor DNA afterward have a higher risk of relapse, she said.
One of the researchers working on those tests is Dr. David Polsky, a professor of dermatologic oncology at NYU Langone Health, in New York City. He agreed that the current study is “interesting.”
“But a lot more validation work needs to be done before it could be used clinically,” Polsky said.
According to Zharov, the approach holds promise for not only monitoring melanoma patients’ responses to treatment, but also catching any recurrences after treatment, or helping to diagnose the cancer in the first place.
There are also hints that the laser might even kill off some of the circulating tumor cells.
For now, though, Zharov said his team is focused on using the technology for diagnosis and monitoring.
There’s also the question of whether the test could weed out circulating tumor cells from other types of cancer. Zharov said that is possible — though the approach would have to be modified because other types of tumor cells do not contain melanin.
The American Cancer Society estimates that about 96,500 Americans will be diagnosed with melanoma this year, and over 7,200 will die from the disease.