What is stomach cancer?
Stomach cancer (also called gastric cancer) starts in the stomach. To understand stomach cancer, it helps to know about the normal structure and function of the stomach.
Stomach or abdomen?
In everyday speech, the word “stomach” is often used to refer to the part of the body between the chest and the hips. For instance, people with pain in the appendix, small intestine, colon, or gallbladder might say they have a “stomach ache.” The medical term for this area is the abdomen and doctors would describe the pain as “abdominal pain.”
The difference is important because the stomach is only one of many organs in the abdomen that cancer can start in. So stomach cancer should not be confused with cancers in other organs in the same area. These other cancers can cause different symptoms. They are treated differently and have a different outlook for survival (prognosis).
After food has been chewed and swallowed, it passes down a tube called the esophagus and goes into the stomach. The stomach is a sack-like organ that holds food and mixes it with gastric juice to begin the process of digestion.
Cancer can start in any part of the stomach. Symptoms, treatment options, and the outlook for survival all depend on where the cancer starts in the stomach.
The stomach wall has 5 layers. It helps to know about these layers because as cancer grows deeper into them, the outlook for the patient gets worse. These are the 5 layers, working from the inside out:
- The innermost layer is called the mucosa. This is where stomach acid and digestive juices are made. It is also where most stomach cancers start.
- The next layer is the submucosa.
- A layer of thick muscle called the muscularis propria moves and mixes the stomach contents.
- The outer 2 layers, the subserosa and the serosa, act as wrapping for the stomach.
Growth of stomach cancer
Most of the time stomach cancer starts in the mucosa and slowly grows out into the other layers.
Stomach cancer tends to grow slowly over many years. Before a true cancer starts, there are usually changes that take place in the inner lining of the stomach (the mucosa). These early changes rarely cause symptoms and often are not noticed.
Cancers starting in different sections (as opposed to layers) of the stomach may cause different symptoms, tend to have different outcomes, and may call for different treatment options. To find out more about the different sections of the stomach, please see our document Stomach Cancer.
How stomach cancer spreads
Stomach cancer can spread in different ways. It can grow through the wall of the stomach and into nearby organs. It can also spread to nearby lymph nodes (bean-sized collections of immune system cells) and then spread through the lymph system. When stomach cancer is more advanced, it can travel through the bloodstream to other organs like the liver, lungs, and bones. If the cancer has spread, the patient’s outlook is not as good.
Types of cancers in the stomach
By far, most cancers of the stomach are a type called adenocarcinomas. This cancer starts from cells that form the lining of the innermost layer, the mucosa. The terms stomach cancer or gastric cancer almost always refers to this type of cancer.
Other stomach tumors
Lymphomas, gastrointestinal stromal tumors (often called GISTs), and carcinoid tumors are other, much less common, tumors that are found in the stomach. The treatment and outlook for these cancers are different from that of adenocarcinoma and are not covered here. The ACS has separate information about these cancers. Please see our documents, Non-Hodgkin Lymphoma, Gastrointestinal Stromal Tumor, or Gastrointestinal Carcinoid Tumors.
The rest of the information here refers only to adenocarcinoma of the stomach.
What are the risk factors for stomach cancer?
A risk factor is anything that affects a person’s chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, such as smoking, can be changed. Others, like a person’s age or family history, can’t be changed. But risk factors don’t tell us everything. Having a risk factor, or even several risk factors, does not mean that you will get the disease. And many people who get the disease may have few or no known risk factors.
Gender: Stomach cancer is more common in men than in women.
Age: There is a sharp increase in stomach cancer after age 50. Most people are between their late 60s and 80s when their cancer is found.
Ethnicity: In the United States, stomach cancer is more common in Hispanic Americans, African Americans, and Asian Pacific Islanders than it is in non-Hispanic whites.
Where a person lives: Worldwide, stomach cancer is more common in Japan, China, Southern and Eastern Europe, and South and Central America. This disease is less common in Northern and Western Africa, South Central Asia, and North America.
Bacterial infection: Infection with bacteria called Helicobacter pylori (H. pylori) seems to be a major cause of stomach cancer. Long-term infection with this germ may lead to inflammation and pre-cancer changes to the inner layer of the stomach. This germ is also linked to ulcers and some types of lymphoma of the stomach. But most people who carry this germ in their stomachs never get cancer.
Stomach lymphoma: People who have been treated for a certain type of stomach lymphoma known as MALT lymphoma have an increased risk of adenocarcinoma of the stomach. This is probably because this stomach lymphoma is caused by infection with H. pylori.
Diet: An increased risk of stomach cancer is seen in people with diets high in smoked foods, salted fish and meats, and pickled vegetables. On the other hand, eating lots of fresh fruits and vegetables seems to lower the risk of stomach cancer.
Tobacco use: Smoking about doubles the risk of stomach cancer.
Being overweight or obese: Being overweight or obese (very overweight) is a possible cause of cancers of the upper part of the stomach, but the strength of this link is not yet clear.
Earlier stomach surgery: Stomach cancer is more likely to be found in people who have had part of their stomach removed to treat other problems like ulcers. These cancers can happen many years after the surgery.
Pernicious anemia: In this disease, the stomach doesn’t make enough of a protein that allows the body to absorb vitamin B12 from foods. This can lead to a shortage of red blood cells (anemia) and other problems. Patients with this disease also have an increased risk of stomach cancer.
Menetrier disease: This rare disease involves changes in the stomach lining that might be linked to a risk of stomach cancer.
Type A blood: For unknown reasons, people with type A blood have a higher risk of getting stomach cancer.
Inherited cancer syndromes: A syndrome is a cluster of symptoms that point to a disease or condition. A number of syndromes that result from gene changes (mutations) inherited from a parent can increase the risk of stomach cancer in people who have them. These syndromes include:
- Hereditary diffuse gastric cancer
- Hereditary non-polyposis colorectal cancer (HNPCC)
- Familial adenomatous polyposis (FAP)
- Hereditary breast and ovarian cancer syndrome
- Li-Fraumeni syndrome
- Peutz-Jeghers syndrome
To find out more about these syndromes, please see the section “What are the risk factors for stomach cancer?” in our document, Stomach Cancer.
Family history: People with close family members (parents, siblings, and children) who have had stomach cancer are more likely to get this disease.
Some types of stomach polyps: Polyps are benign growths on the lining of the stomach. Most polyps do not increase the risk of stomach cancer. But one type (called adenomatous polyps or adenomas) sometimes change into stomach cancer.
Epstein-Barr virus: This virus causes “mono” (infectious mononucleosis). It has been found in the stomach cancers of some people. Almost all adults have had this virus at some time in their lives, often as children or teens. It isn’t yet clear if this virus causes stomach cancer, just that the virus has been found in stomach cancer cells.
Certain types of work: Workers in the coal, metal, and rubber industries seem to have a higher risk of getting stomach cancer.
Immune weakness: People with an immune problem called common variable immunodeficiency (CVID) have an increased risk of stomach cancer. The immune system of someone with CVID can’t make enough antibodies in response to germs. People with CVID have frequent infections as well as other problems. They are also more likely to get gastric lymphoma and stomach cancer.
While there are many risk factors for stomach cancer, we do not know exactly how these factors cause cells of the stomach to become cancer. Scientists are trying to learn how and why certain changes take place in the lining of the stomach and what part H. pylori plays in stomach cancer.
They are also looking at how gene changes (mutations) can cause normal stomach cells to change and form cancers. Most of the gene changes that are linked to stomach cancer take place after birth. Very few are inherited.
How is stomach cancer found?
Screening is the search for a disease like cancer in people without symptoms. Because stomach cancer is not that common in the United States, mass screening for the disease has not been found to be useful. But people at high risk should talk to their doctors about the value of screening.
People who have stomach cancer rarely have symptoms in the early stages of the disease. This is one of the reasons why stomach cancer is so hard to find early. The signs and symptoms of this cancer can include:
- No desire to eat (poor appetite)
- Weight loss (without trying)
- Pain in the area of the stomach (abdominal pain)
- Vague discomfort in the abdomen (belly), often above the navel
- A sense of fullness just below the chest bone after eating a small meal
- Heartburn or indigestion
- Vomiting, with or without blood
- Swelling or fluid build-up in the abdomen
Of course, many of these symptoms can be caused by problems other than cancer. But if you have any of these problems and they don’t go away or get worse, you should see a doctor so the cause can be found and treated.
Medical history and physical exam
If there is any reason to suspect stomach cancer, your doctor will ask you questions about your health, risk factors, and symptoms and do a complete physical exam. The doctor will feel your belly (abdomen) to see if there are any abnormal changes.
If your doctor thinks you might have stomach cancer or another type of stomach problem, he or she will refer you to a gastroenterologist, a doctor who with special training in diseases of the digestive tract, who will examine you and do further testing.
Tests that may be done to find stomach cancer
Upper endoscopy: In this test, drugs are used to make the patient sleepy and then a thin, flexible, lighted tube with a tiny video camera on the end (called an endoscope) is put down the throat. Through the tube, the doctor can see the lining of the esophagus, stomach, and the first part of the small intestine. If anything does not look normal, a tissue sample (biopsy) can be taken out through the tube. These samples are sent to a lab, where they are looked at under a microscope to see if cancer is present and, if so, what type of cancer it is.
Biopsy: The only way to tell for sure if something is really cancer is by doing a biopsy. To do this, the doctor removes a sample of the tissue that doesn’t look normal. This sample is sent to a lab to be looked at under a microscope. Biopsies for stomach cancer are most often done during endoscopy.
Some stomach cancers are deep within the stomach wall, which can make them hard to biopsy with standard endoscopy. If the doctor suspects cancer might be deeper in the stomach wall, endoscopic ultrasound (described below) can be used to guide a thin, hollow needle into the wall of the stomach to get a biopsy sample.
Biopsies may also be taken from places where the cancer might have spread, such as nearby lymph nodes or other parts of the body.
Upper GI (gastrointestinal) series: This is a type of x-ray test. It is not used as often as endoscopy to look for stomach cancer. People having this test drink a chalky liquid that contains barium. The barium coats the lining of the esophagus, stomach, and first part of the small intestine. Because x-rays can’t pass through the coating of barium, anything that isn’t normal in the lining of these organs will be outlined. X-rays are then taken. Sometimes, after the barium is swallowed, a thin tube is passed into the stomach and air is pumped in. This makes the barium coating very thin so that even small areas of change will show up.
Endoscopic ultrasound (EUS): In an ultrasound, sound waves are used to make pictures of organs inside the body. Most people know about ultrasound because it is used to get a picture of the baby before birth. Ultrasound can also be done with a probe put down the throat into the stomach during endoscopy. It lets the doctor look at the layers of the stomach wall, as well as the nearby lymph nodes and other structures just outside the stomach.
EUS is most useful in seeing how far a cancer may have spread into the wall of the stomach, to structures just outside the stomach, and to nearby lymph nodes. It can also be used to help guide a biopsy needle to get a tissue sample.
CT scan (computed tomography): This test uses a special x-ray machine that takes pictures from many angles. A computer then combines these pictures into images of slices of the part of your body being studied. The CT scan can help show where stomach cancer is and can also show the organs near the stomach, such as the liver, as well as lymph nodes and distant organs where cancer might have spread.
A CT scanner has been described as a large donut, with a narrow table that slides in and out of the middle “hole.” You will need to lie still on the table while the scan is being done. CT scans take longer than regular x-rays, and you might feel a bit confined by the ring while the pictures are being taken.
You may be asked to drink 1 or 2 pints of a contrast solution and/or have an IV (intravenous) line through which you get a contrast dye. This can cause some flushing (redness and warm feeling). Some people are allergic and get hives, or — rarely — reactions like trouble breathing and low blood pressure. Be sure to tell the doctor if you have any allergies or ever had a reaction to any dye used for x-rays.
CT scans can also be used to guide a biopsy needle into a place that might have cancer. The patient stays on the CT scanning table while a doctor moves a biopsy needle through the skin toward the tumor. A small piece of the tumor is removed and looked at under a microscope.
MRI scan (magnetic resonance imaging): Like CT scans, MRIs give doctors cross-section pictures of the body. But MRIs use strong magnets instead of x-rays. Sometimes a contrast dye might be used just as with CT scans. Most doctors prefer to use CT scans to look at the stomach, but sometimes an MRI can give more information. MRIs are often used to look at the brain and spinal cord.
MRI scans take longer than CT scans, often up to an hour. You may have to lie inside a narrow tube, which can upset some people. Special, open MRI machines can sometimes help with this. The MRI machine makes loud thumps and buzzes. Some places will give you headphones to block this noise out.
PET scan (positron emission tomography): For this test, a special kind of radioactive sugar is put into your vein. Over time the sugar collects in places that have cancer. After about an hour, you are moved onto a table in the PET scanner. You lie on the table for about 30 minutes while a special camera creates a pictures. PET is sometimes useful if your doctor thinks the cancer might have spread but doesn’t know where. The picture is not as detailed as a CT or MRI scan, but it can show the whole body.
Some machines can do both a PET and CT scan at the same time (PET/CT scan). This can be helpful in some cases. For instance, it may help show if the cancer has spread beyond the stomach to other parts of the body, in which case surgery might not be a good treatment option.
Chest x-ray: This test can be used to tell whether the cancer has spread to the lungs. It may also be useful to find out if you have any lung or heart problems. This test is not needed if a CT scan of the chest has been done.
Laparoscopy: This test may be done after cancer is found to help see how far the cancer has spread. It is done in an operating room with the patient in a deep sleep (under general anesthesia.) A thin, flexible tube with a camera on the end is placed into your belly through a small cut (incision). It sends a picture of the organs inside of the abdomen to a video screen. The doctor can also take biopsy samples from any areas that don’t look normal. The doctor can use this test before surgery to see whether all of the cancer can be removed.
Lab tests: These may include a blood test called a complete blood count (CBC) to look for anemia (a low red blood cell count that may be caused by bleeding), blood chemistry tests to look for signs of cancer spread to the liver, and a fecal occult blood test, which looks for small amounts of blood in the stool.
If cancer is found, the doctor may want to do other tests, especially if you are going to have surgery. For instance, blood tests can be done to make sure your liver and kidneys are working well and your blood is clotting the way it should. You may also have an electrocardiogram (EKG) or other tests to make sure your heart is working well.
How is stomach cancer treated?
This information represents the views of the doctors and nurses serving on the American Cancer Society’s Cancer Information Database Editorial Board. These views are based on their interpretation of studies published in medical journals, as well as their own professional experience.
The treatment information in this document is not official policy of the Society and is not intended as medical advice to replace the expertise and judgment of your cancer care team. It is intended to help you and your family make informed decisions, together with your doctor.
Your doctor may have reasons for suggesting a treatment plan different from these general treatment options. Don’t hesitate to ask him or her questions about your treatment options.
Once your cancer has been found and staged, there is a lot to think about before you and your doctors choose a treatment plan. You may feel that you must make a choice quickly, but it is important to give yourself time to absorb the information you have just learned. Ask your cancer care team questions. You can find some good questions to ask in the section, “What should you ask your doctor about stomach cancer?”
The main treatments for stomach cancer are:
Often the best approach uses 2 or more of these treatment methods.
The choice of treatment depends on several things. The place and stage of the tumor are very important. But other factors to think about are your age, your overall health, and your personal wishes.
It is important that you understand the goal of your treatment. If a cure is not possible, treatment is aimed at relieving symptoms such as trouble eating, pain, or bleeding.
You will most likely have a team of special doctors involved in your care before plans for treating your stomach cancer are made. In most cases, a surgeon, a medical oncologist, and perhaps a radiation oncologist will work on a treatment plan before the start of your treatment. Many other specialists may be involved in your care as well.
If time permits, you may want to get a second opinion about your treatment options. A second opinion can provide you with more information and help you feel more sure about the treatment plan that you choose.
What are some questions I can ask my doctor about stomach cancer?
As you cope with cancer and cancer treatment, you need to have honest, open talks with your doctor. You should feel free to ask any question that’s on your mind, no matter how small it might seem. Here are some questions you might want to ask. Be sure to add your own questions as you think of them. Nurses, social workers, and other members of your health care team may also be able to answer many of your questions.
- Would you please write down the exact type of stomach cancer I have?
- Where in my stomach is the cancer?
- What is the stage of my cancer? What does that mean in my case?
- Do I need any other tests?
- Will I need to see other doctors?
- How much experience do you have treating this type of cancer?
- What treatment choices do I have?
- What do you suggest and why?
- How long will treatment last? What will it involve? Where will it be done?
- What is the goal of this treatment (to cure the cancer, slow its growth, ease symptoms, etc.)?
- What risks or side effects are there to the treatment you suggest? How long are they likely to last?
- Are there any clinical trials I should think about now?
- How could treatment affect my daily life? Will it affect the way I eat?
- What is my expected survival rate, based on my cancer as you see it?
- What are the chances of the cancer coming back after treatment?
- What would my options be if the treatment doesn’t work or if the cancer recurs?
- What should I do to get ready for treatment?
- What type of follow-up will I need after treatment?
Moving on after treatment for stomach cancer
For some people with stomach cancer, treatment may remove or destroy the cancer. Finishing treatment can be both stressful and exciting. You may be relieved to be done with treatment but find it hard not to worry about cancer coming back. (When cancer returns, it is called recurrence.) This is a very common concern among those who have had cancer.
It may take a while before your fears lessen. But it may help to know that many people who have had cancer have learned to live with this uncertainty and are leading full lives. Our document, Living with Uncertainty: The Fear of Cancer Recurrence gives more details about this.
In other people, the cancer may never go away completely. These people may get regular treatments with chemotherapy, radiation, or other treatments to try to help keep the cancer in check. Learning to live with cancer that does not go away can be hard and very stressful. Our document, When Cancer Doesn’t Go Away, talks more about this.
If you have finished treatment, your doctors will still want to watch you closely. During these visits, they will ask about symptoms, do physical exams, and perhaps do lab tests or other tests like CT scans. Follow-up is needed to watch for treatment side effects and to check for cancer that has come back or spread.
Almost any cancer treatment can have side effects. Some may last for a few weeks or months, but others can last the rest of your life. Please tell your cancer care team about any symptoms or side effects that bother you so they can help you manage them. Use this time to ask your health care team questions and discuss any concerns you might have.
Most doctors will want to see you every 3 to 6 months for the first few years, then at least once a year after that. Scans and lab tests are not usually needed at each visit, but might be done if you are having any symptoms or physical problems.
Having surgery for stomach cancer will likely mean that your eating habits will need to change to some extent. You probably won’t be able to eat large amounts of food at one time. Your health care team may suggest that you meet with a nutritionist, who can help you adjust to changes in your eating habits.
People who have had surgery — especially if they had the upper part of their stomach removed — will likely need to have their vitamin blood levels tested and may need to get vitamin supplements, which may include B12 shots (injections). Surgery for stomach cancer often causes problems with your body absorbing vitamin B12, so it can’t be taken as a pill.
It is also important to keep health insurance. While you hope your cancer won’t come back, it could happen. If it does, you don’t want to have to worry about paying for treatment.
Should your cancer come back, our document When Your Cancer Comes Back: Cancer Recurrence helps you manage and cope with this phase of your treatment. You can read it online or call us for a free copy.
Seeing a new doctor
At some point after your cancer is found and treated, you may find yourself in the office of a new doctor. It is important that you be able to give your new doctor the exact details of your diagnosis and treatment. Gathering these details soon after treatment may be easier than trying to get them at some point in the future. Make sure you have this information handy and always keep copies for yourself:
- A copy of your pathology report from any biopsies or surgeries
- If you had surgery, a copy of your operative report
- If you stayed in the hospital, a copy of the discharge summary the doctor wrote when you were sent home
- If you had radiation treatment, a copy of the treatment summary
- If you had chemotherapy or targeted therapies, a list of your drugs, drug doses, and when you took them
- Copies of your x-rays and imaging tests (these can often be placed on a DVD)
What’s new in stomach cancer research?
There is always research going on in the area of stomach cancer. Scientists are looking for causes and ways to prevent this cancer, and doctors are looking for better treatments.
Diet: Research has clearly shown that differences in diet are a key factor in stomach cancer risk around the world. Recent research has shown that diets high in preserved meats and low in fresh fruits and vegetables have been linked with higher risk.
Bacterial infection: Recent research suggests that certain types of H. pylori are more strongly linked to stomach cancer. Some factors linked to blood groups may also impact whether people with H. pylori infection get cancer or not. Further research is needed to help doctors figure out how to use this information to test which people might be at higher risk of stomach cancer.
Chemoprevention is the use of natural or man-made chemicals to lower the risk of cancer. The approaches below might be useful in helping prevent stomach cancer:
Antioxidants: These substances can destroy certain chemicals in cells called free radicals. Free radicals can damage parts of genes, causing cells to die or become cancer. Studies are now going on to look at the role of vitamin C, beta-carotene, vitamin E, and the mineral selenium as antioxidants. Whether these will be able to prevent stomach cancer is not yet known.
Antibiotics: Doctors are looking at whether using antibiotics to treat people who have chronic H. pylori infections will help prevent stomach cancer.
Aspirin and similar drugs: Some (but not all) studies have found that people who take non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin or ibuprofen might have a lower risk of stomach cancer. More research is needed to better define this possible link. In the meantime, doctors generally don’t advise taking these medicines just to try to lower your risk of cancer, as they can cause serious side effects in some people.
Sentinel lymph node mapping
This technique has been used to help see how far cancers like melanoma and breast cancer have spread, but doctors are now studying its use in stomach cancer as well. First, the doctor injects a blue dye and a radioactive substance into the cancer. The dye will go into the lymph nodes where the cancer would first spread. These nodes can be removed and looked at for cancer. If no cancer is seen, then it is not likely to have reached other lymph nodes, so they don’t need to be removed. If cancer is found, then all the lymph nodes will be removed. For stomach cancer, this approach is still in the clinical trial stage. It is not yet ready for widespread use.
Laparoscopic (keyhole) surgery
Laparoscopy is sometimes used to help find the extent of stomach cancer. Doctors are now studying if it can be used to remove small stomach cancers.
In this method, the surgeon makes some small holes in the abdomen, each about an inch long. Special long, thin instruments are put into these holes. One of the instruments has a small video camera on the end. The others are used to cut, staple, or sew sections of the stomach.
The recovery time is often quicker after this type of surgery. But it is not widely used to treat stomach cancer in the United States, and more studies may be needed to prove that it is as good as the standard approach.
Clinical trials are being done to test new chemotherapy (chemo) drugs or new ways to combine drugs. Other studies are looking at the best ways to combine drugs with other treatments like radiation. A good deal of effort is aimed at improving the results of surgery by adding chemo and/or radiation either before or after surgery. Clinical trials of these approaches are going on.
New ways of giving chemo are also being studied. For instance, some doctors are looking at putting chemo drugs right into the abdomen to see if it might work better with fewer side effects.
Chemo drugs affect cells that divide quickly, which is why they often work against cancer cells and normal cells, too. But there are other aspects of cancer cells that make them different from normal cells. In recent years, researchers have developed some new targeted drugs aimed at these differences. Targeted drugs sometimes work when standard chemo drugs don’t. They also tend to have less severe side effects than chemo drugs. These drugs are now being studied for use against a number of cancers, including stomach cancer. Most of this research is focused on combining targeted agents with chemo or with each other.
Immunotherapy is an approach that uses drugs to help the body’s immune system fight the cancer. Treatments that boost the patient’s immune system are being tested in clinical trials.
You can learn more about immunotherapy in our document Immunotherapy. You can read it online or call us for a free copy.
If you want to search for clinical trials in your area, contact the American Cancer Society at 1-800-227-2345 or visit us on the Web at www.cancer.org/clinicaltrials.