I had a FNAC biopsy on a similar sized tumor in the same place. No one mentioned serious complications, they found that the tumor expressed chromogranin, then i did a dota scan which showed the tumor to be a NET, and i had a spleen saving distal pancreatomy last month. Wait and watch is not for everybody. But your doctor should give you a balanced explanation as to why he is hesitant to remove the tumor now.