A blood test can predict early lung cancer prognosis
Cancer cells obtained from a blood test may be able to predict how early-stage lung cancer patients will fare, a team from the University of Michigan has shown.
This information could be used to determine which patients are most likely to benefit from additional therapies to head off the spread of the cancer to other areas of the body.
With a new single cell analysis service in U-M's Comprehensive Cancer Center, the researchers are making the necessary technology more widely available in the university system. They hope these "liquid biopsies" will be offered to patients within the next five years.
Circulating tumour cells, representing only about one in a billion cells in the bloodstream, are largely untapped sources of information about tumours, but new methods are bringing their diagnostic value ever closer to patient care.
Sunitha Nagrath, U-M professor of chemical engineering who designs devices that can capture these rare cells, led a team including oncologists and surgeons to explore how cancer cells escape tumours and travel through the body in the bloodstream. This is how metastases, or satellite tumours elsewhere in the body, are thought to form.
"The tumours were constantly shedding cells even when they were small -- that's one thing we learned," Nagrath said. "Although we define the tumours as early stage, already they are disseminating cells in the body."
Early-stage lung cancer patients, whose tumours may only measure a few millimetres in diameter, are typically treated with surgical removal of the tumour, but the study results suggest that this may not be enough. A handful of patients had tumours that were shedding hundreds or thousands of tumour cells into the lung.
"Even though you removed the tumour, you left behind these hundreds and hundreds of cells," Nagrath said. "If you know this patient walking out of the clinic is going to relapse after less than a year because of these cells, why don't we treat them now?"
With a relatively small sample of 36 patients, the team can't definitively say that an actively shedding tumour will lead to metastasis within a year, but Nagrath is exploring the predictive power of cancer cells drawn from the blood. In particular, the study showed that clusters of two or more tumour cells indicated shorter survival times. Six of the nine patients whose cancer returned during the two to 26 months of follow-up had circulating tumour cells appearing in clusters.
"Ultimately, this method will help us look for and find potential markers for either metastatic spread or cancer detection," said Rishindra Reddy, U-M associate professor of surgery who coordinated the blood samples and designed the study with Nagrath and Nithya Ramnath, an associate professor of medical oncology at the U-M Medical School.
University of Michigan