Q. A 45-year-old male presents with a 6-month history of severe abdominal pain, recurrent peptic ulcers, and diarrhea. The patient reports losing 10 pounds over the past year, and reports experiencing symptoms after eating. Physical examination reveals a distended abdomen and diffuse abdominal tenderness. Further evaluation with a secretin stimulation test shows abnormal results after administration of secretin. The patient's family history is notable for hyperparathyroidism. A CT scan is performed and shows a tumor in the pancreas. What is the most likely diagnosis for this patient based on his symptoms and test results?