Stomach cancer, which is also called gastric cancer, is a growth of cells that starts in the stomach. The stomach is in the upper middle part of the belly, just below the ribs. The stomach helps to break down and digest food.
Stomach cancer can happen in any part of the stomach. In most of the world, stomach cancers happen in the main part of the stomach. This part is called the stomach body.
In the United States, stomach cancer is more likely to start by the gastroesophageal junction. This is the part where the long tube that carries food you swallow meets the stomach. The tube that carries food to the stomach is called the esophagus.
Where the cancer starts in the stomach is one factor health care providers think about when making a treatment plan. Other factors might include the cancer's stage and the type of cells involved. Treatment often includes surgery to remove the stomach cancer. Other treatments may be used before and after surgery.
Stomach cancer treatment is most likely to be successful if the cancer is only in the stomach. The prognosis for people with small stomach cancers is quite good. Many can expect to be cured. Most stomach cancers are found when the disease is advanced and a cure is less likely. Stomach cancer that grows through the stomach wall or spreads to other parts of the body is harder to cure.
Signs and symptoms of stomach cancer may include:
- Trouble swallowing
- Belly pain
- Feeling bloated after eating
- Feeling full after eating small amounts of food
- Not feeling hungry when you would expect to be hungry
- Losing weight without trying
- Feeling very tired
- Stools that look black
Stomach cancer doesn't always cause symptoms in its early stages. When they happen, symptoms might include indigestion and pain in the upper part of the belly. Symptoms might not happen until the cancer is advanced. Later stages of stomach cancer might cause symptoms such as feeling very tired, losing weight without trying, vomiting blood and having black stools.
Stomach cancer that spreads to other parts of the body is called metastatic stomach cancer. It causes symptoms specific to where it spreads. For example, when cancer spreads to the lymph nodes it might cause lumps you can feel through the skin. Cancer that spreads to the liver might cause yellowing of the skin and whites of the eyes. If cancer spreads within the belly, it might cause fluid to fill the belly. The belly might look swollen.
When to see a doctor
If you have signs and symptoms that worry you, make an appointment with your health care provider. Many conditions can cause symptoms that are like the ones caused by stomach cancer. Your provider might test for those other causes first before testing for stomach cancer.
It's not clear what causes stomach cancer. Experts believe most stomach cancers start when something hurts the inside lining of the stomach. Examples include having an infection in the stomach, having long-standing acid reflux and eating a lot of salty foods. Not everyone with these risk factors gets stomach cancer, though. So more research is needed to find out exactly what causes it.
Stomach cancer begins when something hurts cells in the inner lining of the stomach. It causes the cells to develop changes in their DNA. A cell's DNA holds the instructions that tell a cell what to do. The changes tell the cells to multiply quickly. The cells can go on living when healthy cells would die as part of their natural lifecycle. This causes a lot of extra cells in the stomach. The cells can form a mass called a tumor.
Cancer cells in the stomach can invade and destroy healthy body tissue. They might start to grow deeper into the wall of the stomach. In time, cancer cells can break away and spread to other parts of the body. When cancer cells spread to another part of the body it's called metastasis.
Types of stomach cancer
The type of stomach cancer you have is based on the type of cell where your cancer began. Examples of stomach cancer types include:
- Adenocarcinoma. Adenocarcinoma stomach cancer starts in cells that produce mucus. This is the most common type of stomach cancer. Nearly all cancers that start in the stomach are adenocarcinoma stomach cancers.
- Gastrointestinal stromal tumors (GIST). GIST starts in special nerve cells that are found in the wall of the stomach and other digestive organs. GIST is a type of soft tissue sarcoma.
- Carcinoid tumors. Carcinoid tumors are cancers that start in the neuroendocrine cells. Neuroendocrine cells are found in many places in the body. They do some nerve cell functions and some of the work of cells that make hormones. Carcinoid tumors are a type of neuroendocrine tumor.
- Lymphoma. Lymphoma is a cancer that starts in immune system cells. The body's immune system fights germs. Lymphoma can sometimes start in the stomach if the body sends immune system cells to the stomach. This might happen if the body is trying to fight off an infection. Most lymphomas that start in the stomach are a type of non-Hodgkin's lymphoma.
Factors that increase the risk of stomach cancer include:
- Ongoing problems with stomach acid backing up into the esophagus, which is called gastroesophageal reflux disease
- A diet high in salty and smoked foods
- A diet low in fruits and vegetables
- Infection in the stomach caused by a germ called Helicobacter pylori
- Swelling and irritation of the inside of the stomach, which is called gastritis
- Growths of noncancerous cells in the stomach, called polyps
- Family history of stomach cancer
- Family history of genetic syndromes that increase the risk of stomach cancer and other cancers, such as hereditary diffuse gastric cancer, Lynch syndrome, juvenile polyposis syndrome, Peutz-Jeghers syndrome and familial adenomatous polyposis
To lower the risk of stomach cancer, you can:
- Eat plenty of fruits and vegetables. Try to include fruits and vegetables in your diet each day. Choose a 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 and many other types of cancer. Quitting smoking can be very hard, so ask your health care provider for help.
- Tell your health care provider if stomach cancer runs in your family. People with a strong family history of stomach cancer might have stomach cancer screening. Screening tests can detect stomach cancer before it causes symptoms.