Gastric cancer:
Signs and symptoms of gastric cancer may include:
       Fatigue
       Feeling bloated after eating
       Feeling full after eating small amounts of food
       Severe, persistent heartburn
       Severe indigestion that is always present
       Unexplained, persistent nausea
       Stomach pain
       Persistent vomiting
       Unintentional weight loss
Risk factors
The main risk factors for gastric cancer are a history of GERD and obesity.
Factors that increase your risk of stomach cancer located in the stomach body include:
       A diet high in salty and smoked foods
       A diet low in fruits and vegetables
       Family history of stomach cancer
       Infection with Helicobacter pylori
       Long-term stomach inflammation
       Pernicious anemia
       Smoking
       Stomach polyps
Prevention
It's not clear what causes gastric cancer, so there's no way to prevent it. But you can
take steps to reduce risk of stomach cancer by making small changes to your everyday
life. For instance, try to:
       Exercise. Regular exercise is associated with a reduced risk of stomach cancer.
      Try to fit physical activity into your day most days of the week.
       Eat more fruits and vegetables. Try to incorporate more fruits and vegetables
      into your diet each day. Choose a wide variety of colorful fruits and vegetables.
      Reduce the amount of salty and smoked foods you eat. Protect your stomach
      by limiting these foods.
       Stop smoking. If you smoke, quit. If you don't smoke, don't start. Smoking
      increases your risk of stomach cancer, as well as many other types of cancer.
      Quitting smoking can be very difficult, so ask your doctor for help.
       Ask your doctor about your risk of gastroesophageal junction or stomach
      cancer. Talk with your doctor if you have an increased risk of gastroesophageal
      junction cancer or stomach cancer. Together you may consider periodic endoscopy
      to look for signs of stomach cancer.
  Reference
  https://www.mayoclinic.org/diseases-conditions/stomach-cancer/symptoms-
  causes/syc-20352438