Why does stomach cancer cause burping and loss off appetite. is the lost of appetite something that comes and goes?

These symptoms occur in many stomach ailments and are related to disturbance in the function due to disease. They are not disease specific.

These symptoms are not specific for gastric cancer. In fact, the most common symptoms of gastric cancer her weight loss, with no other symptoms. I would not be concerned about gastric cancer if I had the symptoms, but I would try some antacids to see if they would help. If you do not get relief, then you should see your doctor or a gastroenterologist. Good luck.