How Is Stomach Cancer Diagnosed? Doctors typically don't do routine screening for stomach cancer. That's mainly because it's not that common, so getting extra tests often isn't helpful. In fact, the number of stomach cancer cases has declined over the past 6test0 years. If you're at higher risk for it though, talk to your doctor to see how to keep an eye out for it. You may get some of the same tests that you would get if you had symptoms and were looking for a diagnosis.