Some symptoms of gastric cancer appear in the early stages, and knowing these symptoms can help diagnose the disease in a timely manner. According to general practitioner Sanjay Mehta, in the early stages of stomach cancer, symptoms are often vague and may include heartburn, upset stomach, loss of appetite, and nausea and vomiting. Patients may also experience difficulty swallowing, upper abdominal pain and weight loss. Another early sign of stomach cancer can be stomach bleeding, which leads to anemia. Reduced red blood cells can be detected by a blood test, the Daily Express writes. Sanjay Mehta said that some symptoms characteristic of stomach cancer can also indicate other conditions, such as peptic ulcer or acid reflux. In all cases, however, if these symptoms occur, it is advisable to see a physician to find out what is causing them.