When the pancreas* develops tumors that secrete gastrin, the stomach overproduces acid and ulcers form in the gastrointestinal tract. The result is a great deal of pain and discomfort for the body in question; one may experience debilitating stomach cramps, a burning sensation in the abdomen, diarrhea, and vomiting. ZES is certainly not pretty.
It gets worse. Patients with Zollinger-Ellison syndrome (predominantly adult males) are likely to develop malignant tumors in the small bowel, liver and lymph nodes near the pancreas. Sometimes tumors spread to other glands, such as the pituitary and parathyroid.
If you go to the doctor (and you should) complaining of these symptoms, the first thing s/he will do is order a series of gastric tests. This may include measuring your gastrin level, endoscopy, or abdominal CT scanning. Once you've been diagnosed, you can begin treatment.
Most likely the physician will prescribe an acid-suppressant. These suppressants are called proton pump inhibitors (like omeprazole, lansoprazole). Another family of less-potent acid-suppressants, including cimetidine, ranitidine, and famotidine, may be used for treatment.
These medications work to heal the ulcers and provide relief of symptoms.
In some cases, surgery to remove the tumors is an option as long as they haven't spread to other areas. Most folks, however, will respond well enough to medication. Thanks to the wonders of modern medicine, gastrectomy is no longer a necessity for ZES patients.
As always, consult a physician as soon as possible; the best defense against ZES is early detection.
Mmmm... eMedicine.com
Chark says it can be other organs in the tummy region, not just the pancreas.