Gastrinomas and Whipple procedure

Hey all, my husband has recently been diagnosed with a 4.9 cm PNet gastrinoma grade 2 stage 4. After upper gi bleed , double pulmonary embolism, damaged esophagus finally were able to get a biopsy of the mass. They were going to do a whipple procedure pending Dot.scan. after revue they are sending us to Mayo. What to expect???