When cancers metastasize, this can reduce patients' chances of survival. Patients with only a few metastases, described as oligometastases, may benefit from aggressive treatment. Research published in PLoS One suggests that levels of biomarkers could identify those patients in whom aggressive, targeted radiation therapy could make a real difference.
The biomarker research follows an initial study published in 2004, in which patients with a few small metastases were given targeted radiotherapy, and all evidence of disease was eradicated in around 1 in 5 individuals. In a follow-up published in 2011, 18% saw no further disease progression and 27% developed no new metastases.
The researchers took tissue samples from the patients who responded well to the treatment and compared them with samples from people whose cancer spread, and found higher levels of the biomarker microRNA-200c in the latter group. This was supported in animal studies, in which increasing levels of microRNA-200c increased the chance of metastasis.
"Our findings are an initial step in discriminating between patients with a few treatable sites where the tumor has spread and those who will develop widespread metastasis, which is not curable with focused radiation therapy," said study author Dr. Ralph Weichselbaum, professor and chair of radiation and cellular oncology and director of the Ludwig Center for Metastasis Research at the University of Chicago. "It is encouraging to find a common molecular basis for this treatable state across a broad variety of metastases from solid tumors."
Care needs to be taken in analysis of data from studies of this type, as a recent study suggested that some miRNA from blood cells may be the same as miRNAs associated with cancers. However, oligometastases can occur in up to 5% of some cancers, and judging quickly which patients will benefit from targeted radiotherapy or systemic chemotherapy could improve quality of life for both subsets.
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