how to terminate a thread started with BeginInvoke?

here is my code:
//*** snippet start
string arg = "";
WorkDelegate d = new WorkDelegate(Printing);
IAsyncResult res = d.BeginInvoke(arg,null,null);
if(res.IsCompleted == false)
{
res.AsyncWaitHandle.WaitOne(5000,false);
if(res.IsCompleted == false)
{
throw new ApplicationException("Timeout");
}
}
return d.EndInvoke((AsyncResult)res);
//*** snippet end

// Printing method
private object Printing(string arg){
this.printDocument1.Print();
return true;
}

This partially works as it throws the exception if the method Printing
didn't complete within 5 seconds but the problem is that the thread itself
running the Printing method keeps running.
Printing is a method that uses the printDocument object to print receipts
using the Windows drivers. If the printer is not available, this method will
be stuck as it if keeps trying. I'd like to terminate the thread when the
exception is thrown but I can't figure out how.

thanks