http://jco.ascopubs.org/content/29/19/2683.abstract

They noted that oncology patients visited the Emergency Department frequently, which we alread knew anecdotely. 

However, the thing to keep in mind was that the most common were, "pain, respiratory distress, and GI issues".  All of which point of care ultrasound can play a role in establishing the diagnosis or reducing the time frame to the diagnosis.  It can also assist in the treatment of the problems, such as with US guided procedures.