Stomach cancer begins when cancer cells form in the inner lining of your stomach. These cells can grow into a tumor. Also called gastric cancer, the disease usually grows slowly over many years. Stomach cancer is most often seen in people in their late 60s through 80s.
Almost all stomach cancers (about 95%) start in the glandular tissue that lines the stomach. The tumor may spread along the stomach wall or may grow directly through the wall and shed cells into the bloodstream or lymphatic system. Once beyond the stomach, cancer can spread to other organs.
Stomach cancers are classified according to the type of tissue they start in.
- Adenocarcinomas -- the most common -- start in the glandular stomach lining.
- Lymphomas develop from lymphocytes, a type of blood cell involved in the immune system.
- Sarcomas involve the connective tissue (muscle, fat, or blood vessels).
- Other types include carcinoid, small cell carcinoma, and squamous cell carcinoma.
- Metastatic cancers from breast cancer, melanoma, and other primary sites of cancer are also seen in the stomach.
If you know the symptoms of stomach cancer, you and your doctor may be able to spot it early, when it’s easiest to treat.
What Causes Stomach Cancer?
Scientists don’t know exactly what makes cancer cells start growing in the stomach. But they do know a few things that can raise your risk for the disease. One of them is infection with a common bacteria, H. pylori, which causes ulcers. Inflammation in your gut called gastritis, a certain type of long-lasting anemia called pernicious anemia, and growths in your stomach called polyps also can make you more likely to get cancer.
Other things that seem to play a role in raising the risk include:
- Being overweight or obese
- A diet high in smoked, pickled, or salty foods
- Drinking alcohol regularly
- Stomach surgery for an ulcer
- Type-A blood
- Epstein-Barr virus infection
- Certain genes
- Working in coal, metal, timber, or rubber industries
- Exposure to asbestos
- Family history of gastric cancer
- Hereditary factors such as familial adenomatous polyposis, hereditary non-polyposis colorectal cancer (Lynch syndrome), and Peutz-Jeghers syndrome
What Are the Symptoms of Stomach Cancer?
Early on, stomach cancer may cause:
Just having indigestion or heartburn after a meal doesn’t mean you have cancer. But if you feel these symptoms a lot, talk to your doctor. They can see if you have other risk factors and test you to look for any problems.
As stomach tumors grow, you may have more serious symptoms, such as:
- Stomach pain
- Blood in your stool
- Weight loss for no reason
- Trouble swallowing
- Yellowish eyes or skin
- Swelling in your stomach
- Constipation or diarrhea
- Weakness or feeling tired
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 60 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.
To find out if you have stomach cancer, your doctor starts with a physical exam. They'll also ask about your medical history to see if you have any risk factors for stomach cancer or any family members who’ve had it. Then, they might give you some tests, including:
- Blood tests to look for signs of cancer in your body.
- Upper endoscopy. Your doctor will put a thin, flexible tube with a small camera down your throat to look into your stomach.
- Upper GI series test. You’ll drink a chalky liquid with a substance called barium. The fluid coats your stomach and makes it show up more clearly on X-rays.
- CT scan.This is a powerful X-ray that makes detailed pictures of the inside of your body.
- Biopsy.Your doctor takes a small piece of tissue from your stomach to look at under a microscope for signs of cancer cells. They might do this during an endoscopy.
What Are Stomach Cancer Treatments?
Many treatments can fight stomach cancer. The one you and your doctor choose will depend on how long you've had the disease or how much it has spread in your body, called the stage of your cancer:
Stage 0. This is when the inside lining of your stomach has a group of unhealthy cells that may turn into cancer. Surgery usually cures it. Your doctor may remove part or all of your stomach, as well as nearby lymph nodes -- small organs that are part of your body's germ-fighting system.
Stage I. At this point, you have a tumor in your stomach's lining, and it may have spread into your lymph nodes. As with stage 0, you'll likely have surgery to remove part or all of your stomach and nearby lymph nodes. You might also get chemotherapy or chemoradiation. These treatments can be used before surgery to shrink the tumor and afterward to kill any cancer that's left.
Chemotherapy uses drugs to attack cancer cells. Chemoradiation is chemo plus radiation therapy, which destroys cancer cells with beams of high energy.
Stage II. Cancer has spread into deeper layers of the stomach and maybe into nearby lymph nodes. Surgery to remove part or all of your stomach, as well as nearby lymph nodes, is still the main treatment. You're very likely to get chemo or chemoradiation beforehand, and you might get one of them after, too.
Stage III. The cancer may now be in all layers of the stomach, as well as other organs close by, like the spleen or colon. Or, it may be smaller but reach deep into your lymph nodes.
You usually have surgery to remove your entire stomach, along with chemo or chemoradiation. This can sometimes cure it. If not, it can at least help with symptoms.
If you're too sick for surgery, you may get chemo, radiation, or both, depending on what your body can handle.
Stage IV. In this last stage, cancer has spread far and wide to organs like the liver, lungs, or brain. It's much harder to treat, but your doctor can help manage it and give you some relief from symptoms.
If the tumor blocks part of your GI system, you may get:
- A procedure that destroys part of the tumor with a laser on an endoscope, a thin tube that slides down your throat.
- A thin metal tube called a stent that can keep things flowing. You can get one of these between your stomach and esophagus or between your stomach and small intestine.
- Gastric bypass surgery to create a route around the tumor.
- Surgery to remove part of your stomach.
Chemo, radiation, or both may be used at this stage, too. You might also get targeted therapy. These drugs attack cancer cells, but leave healthy ones alone, which may mean fewer side effects.
How Can I Prevent Stomach Cancer?
Treat stomach infections. If you have ulcers from an H. pylori infection, get treatment. Antibiotics can kill the bacteria, and other drugs will heal the sores in the lining of your stomach to cut your risk of cancer.
Eat healthy. Get more fresh fruits and vegetables on your plate every day. They’re high in fiber and in some vitamins that can lower your cancer risk. Avoid very salty, pickled, cured, or smoked foods like hot dogs, processed lunch meats, or smoked cheeses. Keep your weight at a healthy level, too. Being overweight or obese can also raise your risk of the disease.
Don’t smoke. Your stomach cancer risk doubles if you use tobacco.
Limit your alcohol. Recent research suggests that the risk of stomach cancer increases with how often you drink.