The microRNAs associated with oligometastasis have tumor suppressor characteristics that differ from microRNAs associated with patients who developed widespread metastatic disease. Oligometastasis is an intermediate state between extensive metastasis and a locally confined tumor. These results demonstrate a biological basis for oligometastasis and the potential to use microRNA expression to identify patients most likely to remain oligometastatic after metastasis-directed treatment.
More than 15 years ago, scientists hypothesized that an intermediate state of tumor spread or metastasis exists between patients with extensive metastasis and patients who disease stays confined to one local tumor with no spread. The scientists demonstrated that some patients with oligometastases can be cured with therapies, including surgery and radiotherapy, directed locally at the metastasis.
This study took the research a step further by analyzing patients with lung metastases who underwent surgical resection with curative intent. They found that some patients were cured, some developed rapid metastasis, and some developed metastasis at a very slow rate of progression. When they investigated what accounted for these radical differences in patient outcomes, they found microRNAs were the reason for the differences in outcomes.
MicroRNAs are small molecules that suppress gene expression or protein synthesis. The investigators identified microRNAs associated with oligometastic progression and found that these differed from those associated with patients who developed widespread metastatic disease.
“With these findings, we are now able to use microRNA expression to characterize oligometastasis and ultimately better select patients with tumor metastasis for curative interventions,” said study author Ralph Weichselbaum, MD, of the University of Chicago. “Also understanding the molecular basis of tumor metastasis will allow for the targeting of specific biological processes to treat patients with more advanced tumor spread.”
This study was published in PLoS ONE (2012; doi:10.1371/journal.pone.0050141).