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A new, noninvasive method for measuring circulating tumor cells in patients with breast cancer [
American Association for Cancer Research]
Researchers report a new, noninvasive method for measuring circulating tumor cells in patients with breast cancer, information which can be used to predict the likelihood that cancer will spread. The technique detects circulating tumor cells with 100 percent specificity and 88 percent sensitivity, researchers report.
"Metastasis, or the spread of cancer beyond the original site, is the main cause of death in breast cancer," said Tim Molloy, Ph.D., a post-doctoral fellow at the Netherlands Cancer Institute. "If we can improve ways of measuring risk of metastasis, we can more effectively target therapy and manage these patients."
Specificity is a statistical calculation that measures the likelihood that a negative result will be associated with the absence of disease. Sensitivity measures the likelihood that a positive result will be associated with disease.
Molloy and colleagues used a quantitative polymerase chain reaction-based detection platform that combined genetic information from four accepted tumor markers into a single score. The higher the score, the greater likelihood of circulating tumor cells.
When researchers applied this test to 131 individuals, an elevated score was observed in 88 percent of patients with metastatic breast cancer, 18 percent of patients with non-metastatic breast cancer and none of the healthy control participants.
After identifying patients whose tumors gave rise to high numbers of circulating tumor cells, a technique called microarray analysis was used to build a genetic profile of their tumors. Microarrays allow researchers to look at thousands of genes simultaneously in a particular cell or tissue to determine which are activated at the time of sampling. From these data Molloy and colleagues were able to build a specific 'genetic fingerprint' of breast tumors which may give rise to large numbers of circulating tumor cells.
With this knowledge it was possible to use microarray analysis to predict whether a tumor was likely to disseminate large numbers of tumor cells and therefore metastasize in the future. Testing this on a small independent patient group, researchers found those with a tumor having a genetic profile corresponding to lower levels of circulating tumor cells had a longer time to metastasis at 51.4 months, compared with 29.6 months among those who had a tumor with a genetic profile consistent with higher levels of circulating tumor cells.
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