Frequent vomiting with blood or struggling to swallow food are the symptoms that show up when the cancer becomes serious. However, very early signs of stomach cancer can mimic common indigestion symptoms. Reports suggest that very early symptoms of stomach cancer closely resemble indigestion, it becomes even difficult to detect it.Frequent vomiting with blood or struggling to swallow food are the symptoms that show up when the cancer becomes serious. However, very early signs of stomach cancer can mimic common indigestion symptoms. Reports suggest that very early symptoms of stomach cancer closely resemble indigestion, it becomes even difficult to detect it.