Cancers that have spread throughout the body, a process known as metastasis, are difficult, often impossible, to control. They are the leading cause of cancer-related deaths.
Twenty years ago, however, two University of Chicago cancer specialists — Samuel Hellman, former dean of the University of Chicago’s Division of the Biological Sciences, and Ralph Weichselbaum, chairman of radiation oncology — described what they considered an intermediate and potentially treatable state between a single tumor and widespread cancer. They labelled it oligometastasis.
Like oligarchy, the rule of the few, oligometastasis denotes a stage of cancer in which a primary tumor has spawned only a few localized secondary tumors, typically no more than five. The two researchers, nationally recognized authorities on radiation therapy for cancer, suggested and subsequently proved that oligometastatic tumors could often be cured with targeted local treatment such as surgery or focused radiation.
In the February 2015 issue of the journal Oncotarget, Weichselbaum, co-director of the Ludwig Center for Metastasis Research at the University of Chicago, and colleagues present the first glimpse of the biological mechanisms behind oligometastasis.
They gathered genetic information from tumor samples from their own published clinical trials, the only known datasets of patients with oligometastases. They used this information to identify small clusters of gene-blocking microRNAs expressed only by oligometastatic cells. They also show how certain microRNAs can shut down specific genes, by attaching to their messenger RNA, essentially silencing them.