Cancer starts when cells in the body begin to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other areas of the body. To learn more about how cancers start and spread, see What Is 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.

Survival rates tell you what portion of people with the same type and stage of cancer are still alive a certain length of time (usually 5 years) after they were diagnosed. These numbers can’t tell you how long you will live, but they might help give you a better understanding about how likely it is that your treatment will be successful.

What is a 5-year survival rate?

Statistics on the outlook for people with a certain type and stage of cancer are often given as 5-year survival rates, but many people live longer – often much longer – than 5 years. The 5-year survival rate is the percentage of people who live at least 5 years after being diagnosed with cancer. For example, a 5-year survival rate of 90% means that an estimated 90 out of 100 people who have that cancer are still alive 5 years after being diagnosed.

Relative survival rates are a more accurate way to estimate the effect of cancer on survival. These rates compare people with stomach cancer to people in the overall population. For example, if the 5-year relative survival rate for a specific type and stage of cancer is 90%, it means that people who have that cancer are, on average, about 90% as likely as people who don’t have that cancer to live for at least 5 years after being diagnosed.

But remember, the 5-year relative survival rates are estimates – your outlook can vary based on a number of factors specific to you.

Cancer survival rates don’t tell the whole story

Survival rates are often based on previous outcomes of large numbers of people who had the disease, but they can’t predict what will happen in any particular person’s case. There are a number of limitations to remember:

• The numbers below are among the most current available. But to get 5-year survival rates, doctors have to look at people who were treated at least 5 years ago. As treatments are improving over time, people who are now being diagnosed with stomach cancer may have a better outlook than these statistics show.
• These statistics are based on the stage of the cancer when it was first diagnosed. They do not apply to cancers that come back later or spread, for example.
• Besides the cancer stage, many other factors can affect a person's outlook, such as age and overall health, and how well the cancer responds to treatment.

Your doctor can tell you how these numbers may apply to you, as he or she is familiar with your situation.

Stomach cancer survival rates, by stage

These survival rates come from the National Cancer Database (NCDB) and were published in 2017 in the 8th edition of the AJCC Staging Manual. They are based on people diagnosed with stomach cancer and treated with surgery between 2004 and 2008. Survival rates for patients not treated with surgery are likely to be lower. It is also important to note that these are observed survival rates. People with cancer can die of other things, and these rates do not take that into account.

The 5-year survival rates by stage for stomach cancer treated with surgery are as follows:

Stage	5 year observed survival
Stage IA	94%
Stage IB	88%
Stage IIA	82%
Stage IIB	68%
Stage IIIA	54%
Stage IIIB	36%
Stage IIIC	18%

The overall 5-year relative survival rate of all people with stomach cancer in the United States is about 31%. The 5-year relative survival rate compares the observed survival of people with stomach cancer to that expected for people without stomach cancer. Since some people may die from other causes, this is a better way to see the impact of cancer on survival.

This survival rate has improved gradually over the last 30 years. One reason the overall survival rate is poor in the United States is that most stomach cancers are diagnosed at an advanced rather than an early stage. The stage of the cancer has a major effect on a patient’s prognosis (outlook for survival).

Treatment of stomach cancer depends to a large degree on where the cancer started in the stomach and how far it has spread.

Stomach cancers can grow and spread in different ways. They can grow through the wall of the stomach and invade nearby organs. They can also spread to the lymph vessels and nearby lymph nodes (bean-sized structures that help fight infections). The stomach has a very rich network of lymph vessels and nodes. As the stomach cancer becomes more advanced, it can travel through the bloodstream and spread (metastasize) to organs such as the liver, lungs, and bones, which can make it harder to treat.

Stage 0

Because stage 0 cancers are limited to the inner lining layer of the stomach and have not grown into deeper layers, they can be treated by surgery alone. No chemotherapy or radiation therapy is needed.

Surgery with either subtotal gastrectomy (removal of part of the stomach) or total gastrectomy (removal of the entire stomach) is often the main treatment for these cancers. Nearby lymph nodes are removed as well.

Some small stage 0 cancers can be treated by endoscopic resection. In this procedure the cancer is removed through an endoscope passed down the throat. This is done more often in Japan, where stomach cancer is often detected early during screening. It is rare to find stomach cancer so early in the United States, so this treatment has not been used as much here. If it is done, it should be at a cancer center that has a great deal of experience with this technique.

Stage I

Stage IA: People with stage IA stomach cancer typically have their cancer removed by total or subtotal gastrectomy. The nearby lymph nodes are also removed. Endoscopic resection may rarely be an option for some small T1a cancers. No further treatment is usually needed after surgery.

Stage IB: The main treatment for this stage of stomach cancer is surgery (total or subtotal gastrectomy). Chemotherapy (chemo) or chemoradiation (chemo plus radiation therapy) may be given before surgery to try to shrink the cancer and make it easier to remove.

After surgery, patients whose lymph nodes (removed at surgery) show no signs of cancer spread are sometimes observed without further treatment, but often doctors will recommend treatment with either chemoradiation or chemo alone after surgery (especially if the patient didn’t get one of these before surgery). Patients who were treated with chemo before surgery may get the same chemo (without radiation) after surgery.

If cancer is found in the lymph nodes, treatment with either chemoradiation, chemo alone, or a combination of the two is often recommended.

If a person is too sick (from other illnesses) to have surgery, they may be treated with chemoradiation if they can tolerate it. Other options include radiation therapy or chemo alone.

Stage II

The main treatment for stage II stomach cancer is surgery to remove all or part of the stomach, the omentum, and nearby lymph nodes. Many patients are treated with chemo or chemoradiation before surgery to try to shrink the cancer and make it easier to remove. Treatment after surgery may include chemo alone or chemoradiation.

If a person is too sick (from other illnesses) to have surgery, they may be treated with chemoradiation if they can tolerate it. Other options include radiation therapy or chemo alone.

Stage III

Surgery is the main treatment for patients with this stage disease (unless they have other medical conditions that make them too ill for it). Some patients may be cured by surgery (along with other treatments), while for others the surgery may be able to help control the cancer or help relieve symptoms.

Some people may get chemo or chemoradiation before surgery to try to shrink the cancer and make it easier to remove. Patients who get chemo before surgery will probably get chemo after, as well. For patients who don’t get chemo before surgery and for those who have surgery but have some cancer left behind, treatment after surgery is usually chemoradiation.

If a person is too sick (from other illnesses) to have surgery, they may be treated with chemoradiation if they can tolerate it. Other options include radiation therapy or chemo alone.

Stage IV

Because stage IV stomach cancer has spread to distant organs, a cure is usually not possible. But treatment can often help keep the cancer under control and help relieve symptoms. This might include surgery, such as a gastric bypass or even a subtotal gastrectomy in some cases, to keep the stomach and/or intestines from becoming blocked (obstructed) or to control bleeding.

In some cases, a laser beam directed through an endoscope (a long, flexible tube passed down the throat) can destroy most of the tumor and relieve obstruction without surgery. If needed, a stent (a hollow metal tube) may be placed where the esophagus and stomach meet to help keep it open and allow food to pass through it. This can also be done at the junction of the stomach and the small intestine.

Chemo and/or radiation therapy can often help shrink the cancer and relieve some symptoms as well as help patients live longer, but is usually not expected to cure the cancer. Combinations of chemo drugs are most commonly used, but which combination is best is not clear.

Targeted therapy can also be helpful in treating advanced stomach cancers. Trastuzumab (Herceptin) can be added to chemotherapy for patients whose tumors are HER2-positive. Ramucirumab (Cyramza) may also be an option at some point. It can be given by itself or added to chemo. The immunotherapy drug pembrolizumab (Keytruda) might also be an option at some point.

Because these cancers can be hard to treat, new treatments being tested in clinical trials may benefit some patients.

Even if treatments do not destroy or shrink the cancer, there are ways to relieve pain and symptoms from the disease. Patients should tell their cancer care team about any symptoms or pain they have right way, so they can be managed effectively.

Nutrition is another concern for many patients with stomach cancer. Help is available ranging from nutritional counseling to placement of a tube into the small intestine to help provide nutrition for those who have trouble eating, if needed.

Recurrent cancer

Cancer that comes back after initial treatment is known as recurrent cancer. Treatment options for recurrent disease are generally the same as they are for stage IV cancers. But they also depend on where the cancer recurs, what treatments a person has already had, and the person’s general health.

Clinical trials or newer treatments may be an option and should always be considered.

Early-stage stomach cancer rarely causes symptoms. This is one of the reasons stomach cancer is so hard to detect early. The signs and symptoms of stomach cancer can include:

• Poor appetite
• Weight loss (without trying)
• Abdominal (belly) pain
• Vague discomfort in the abdomen, usually above the navel
• A sense of fullness in the upper abdomen after eating a small meal
• Heartburn or indigestion
• Nausea
• Vomiting, with or without blood
• Swelling or fluid build-up in the abdomen
• Blood in the stool
• Low red blood cell count (anemia)

Most of these symptoms are more likely to be caused by things other than cancer, such as a stomach virus or an ulcer. They may also occur with other types of cancer. But people who have any of these problems, especially if they don’t go away or get worse, should check with their doctor so the cause can be found and treated.

Since symptoms of stomach cancer often do not appear until the disease is advanced, only about 1 in 5 stomach cancers in the United States is found at an early stage, before it has spread to other areas of the body.

Chemotherapy (chemo) uses anti-cancer drugs that are injected into a vein or given by mouth as pills. These drugs enter the bloodstream and reach all areas of the body, making this treatment useful for cancer that has spread to organs beyond where it started.

Chemo can be used in different ways to help treat stomach cancer:

• Chemo can be given before surgery for stomach cancer. This, known as neoadjuvant treatment, can shrink the tumor and possibly make surgery easier. It may also help keep the cancer from coming back and help patients live longer. For some stages of stomach cancer, neoadjuvant chemo is one of the standard treatment options. Often, chemo is then given again after surgery.
• Chemo may be given after surgery to remove the cancer. This is called adjuvant treatment. The goal of adjuvant chemo is to kill any cancer cells that may have been left behind but are too small to see. This can help keep the cancer from coming back. Often, for stomach cancer, chemo is given with radiation therapy after surgery. This combination is called chemoradiation. This may be especially helpful for cancers that could not be removed completely by surgery.
• Chemo may be given as the primary (main) treatment for stomach cancer that has spread (metastasized) to distant organs. It may help shrink the cancer or slow its growth, which can relieve symptoms for some patients and help them live longer.

Doctors give chemo in cycles, with each period of treatment followed by a rest period to allow the body time to recover. Each cycle typically lasts for a few weeks.

A number of chemo drugs can be used to treat stomach cancer, including:

• 5-FU (fluorouracil), often given along with leucovorin (folinic acid)
• Capecitabine (Xeloda^®)
• Carboplatin
• Cisplatin
• Docetaxel (Taxotere^®)
• Epirubicin (Ellence^®)
• Irinotecan (Camptosar^®)
• Oxaliplatin (Eloxatin^®)
• Paclitaxel (Taxol^®)

Depending on the situation (including the stage of the cancer, the person’s overall health, and whether chemo is combined with radiation therapy), these drugs may be used alone or combined with other chemotherapy or targeted drugs.

Some common drug combinations used when surgery is planned include:

• ECF (epirubicin, cisplatin, and 5-FU),which may be given before and after surgery
• Docetaxel or paclitaxel plus either 5-FU or capecitabine, combined with radiation as treatment before surgery
• Cisplatin plus either 5-FU or capecitabine, combined with radiation as treatment before surgery
• Paclitaxel and carboplatin, combined with radiation as treatment before surgery

When chemo is given with radiation after surgery, a single drug such as 5-FU or capecitabine may be used.

To treat advanced stomach cancer, ECF may also be used, but other combinations may also be helpful. Some of these include:

• DCF (docetaxel, cisplatin and 5-FU)
• Irinotecan plus cisplatin
• Irinotecan plus 5-FU or capecitabine
• Oxaliplatin plus 5-FU or capecitabine

Many doctors prefer to use combinations of 2 chemo drugs to treat advanced stomach cancer. Three-drug combinations can have more side effects, so they are usually reserved for people who are in very good health and who can be followed closely by their doctor.

Side effects of chemotherapy

Chemo drugs attack cells that are dividing quickly, which is why they work against cancer cells. But other cells in the body, such as those in the bone marrow (where new blood cells are made), the lining of the mouth and intestines, and the hair follicles, also divide quickly. These cells can also be affected by chemo, which can lead to side effects. The type of side effect depends on the type of drugs, the amount taken, and the length of treatment. Short-term side effects common to most chemotherapy drugs can include:

• Nausea and vomiting
• Loss of appetite
• Hair loss
• Diarrhea
• Mouth sores
• Increased chance of infection (from a shortage of white blood cells)
• Bleeding or bruising after minor cuts or injuries (from a shortage of platelets)
• Fatigue and shortness of breath (from a shortage of red blood cells)

These side effects are usually short-term and go away once treatment is finished. For example, hair will usually grow back after treatment ends. Be sure to tell your cancer care team about any side effects you have because there are often ways to lessen them. For example, you can be given drugs to prevent or reduce nausea and vomiting.

Some chemotherapy drugs have specific side effects. You should be given specific information about each drug you are receiving and you should review it before you start treatment.

Neuropathy: Cisplatin, oxaliplatin, docetaxel, and paclitaxel can damage nerves outside the brain and spinal cord. This can sometimes lead to symptoms (mainly in the hands and feet) such as pain, burning or tingling sensations, sensitivity to cold or heat, or weakness. In most cases this goes away once treatment is stopped, but it may be long-lasting in some patients. Oxaliplatin can also affect nerves in the throat, causing throat pain that is worse when trying to eat or drink cold liquids or foods. This pain can lead to trouble swallowing or even breathing, and can last a few days after treatment.

Heart damage: Doxorubicin, epirubicin, and some other drugs may cause permanent heart damage if used for a long time or in high doses. For this reason, doctors carefully control the doses and use heart tests such as echocardiograms or MUGA scans to monitor heart function. Treatment with these drugs is stopped at the first sign of heart damage.

Hand-foot syndrome can occur during treatment with capecitabine or 5-FU (when given as an infusion). This starts out as redness in the hands and feet, which can then progress to pain and sensitivity in the palms and soles. If it worsens, blistering or skin peeling can occur, sometimes leading to open, painful sores. There is no specific treatment, although some creams may help. These symptoms gradually get better when the drug is stopped or the dose is decreased. The best way to prevent severe hand-foot syndrome is to tell your doctor when early symptoms come up, so that the drug dose can be changed.

To learn more, see Chemotherapy.

Cancer survivors can be affected by a number of health problems, but often their greatest concern is facing cancer again. If a cancer comes back after treatment it is called a recurrence. But some cancer survivors may develop a new, unrelated cancer later. This is called a second cancer. No matter what type of cancer you have had, it is still possible to get another (new) cancer, even after surviving the first.

Unfortunately, being treated for cancer doesn’t mean you can’t get another cancer. People who have had cancer can still get the same types of cancers that other people get. In fact, certain types of cancer and cancer treatments can be linked to a higher risk of certain second cancers.

Survivors of stomach cancer can get any type of second cancer. They do not get second cancers at an increased rate overall, but they do have an increased risk of cancers of the thyroid and small intestine.

Follow-up after treatment

After completing treatment for stomach cancer, you should still see your doctor regularly and may have tests to look for signs the cancer has come back or spread. Experts do not recommend any additional testing to look for second cancers in patients without symptoms. Let your doctor know about any new symptoms or problems, because they could be caused by the cancer coming back or by a new disease or second cancer.

Survivors of stomach cancer should follow the American Cancer Society guidelines for the early detection of cancer and stay away from tobacco products. Smoking increases the risk of many cancers.

To help maintain good health, survivors should also:

• Get ot and stay at a healthy weight
• Adopt a physically active lifestyle
• Eat a healthy diet, with an emphasis on plant foods
• Limit alcohol to no more than 1 drink per day for women or 2 per day for men

These steps may also lower the risk of some cancers.

See Second Cancers in Adults for more information about causes of second cancers.

A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t be changed.

But, 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.

Scientists have found several risk factors that make a person more likely to get stomach cancer.  Some of these can be controlled, but others cannot.

Gender

Stomach cancer is more common in men than in women.

Age

There is a sharp increase in stomach cancer rates in people over age 50. Most people diagnosed with stomach cancer are between their late 60s and 80s.

Ethnicity

In the United States, stomach cancer is more common in Hispanic Americans, African Americans, Native Americans, and Asian/Pacific Islanders than it is in non-Hispanic whites.

Geography

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.

Helicobacter pylori infection

Infection with Helicobacter pylori (H pylori) bacteria seems to be a major cause of stomach cancer, especially cancers in the lower (distal) part of the stomach. Long-term infection of the stomach with this germ may lead to inflammation (called chronic atrophic gastritis) and pre-cancerous changes of the inner lining of the stomach. 

People with stomach cancer have a higher rate of H pylori infection than people without this cancer. H pylori infection is also linked to some types of lymphoma of the stomach. Even so, most people who carry this germ in their stomach never develop cancer.

Stomach lymphoma

People who have had a certain type of lymphoma of the stomach known as mucosa-associated lymphoid tissue (MALT) lymphoma have an increased risk of getting adenocarcinoma of the stomach. This is probably because MALT lymphoma of the stomach is caused by infection with H pylori bacteria.

Diet

An increased risk of stomach cancer is seen in people with diets that have large amounts of smoked foods, salted fish and meat, and pickled vegetables. Nitrates and nitrites are substances commonly found in cured meats. They can be converted by certain bacteria, such as H pylori, into compounds that have been shown to cause stomach cancer in lab animals.

On the other hand, eating lots of fresh fruits and vegetables appears to lower the risk of stomach cancer. 

Tobacco use

Smoking increases stomach cancer risk, particularly for cancers of the upper portion of the stomach near the esophagus. The rate of stomach cancer is about doubled in smokers.

Being overweight or obese

Being overweight or obese is a possible cause of cancers of the cardia (the upper part of the stomach nearest the esophagus), but the strength of this link is not yet clear.

Previous stomach surgery

Stomach cancers are more likely to develop in people who have had part of their stomach removed to treat non-cancerous diseases such as ulcers. This might be because the stomach makes less acid, which allows more nitrite-producing bacteria to be present. Reflux (backup) of bile from the small intestine into the stomach after surgery might also add to the increased risk. These cancers typically develop many years after the surgery.

Pernicious anemia

Certain cells in the stomach lining normally make a substance called intrinsic factor (IF) that we need to absorb vitamin B12 from foods. People without enough IF may end up with a vitamin B12 deficiency, which affects the body’s ability to make new red blood cells and can cause other problems as well. This condition is called pernicious anemia. Along with anemia (too few red blood cells), people with this disease have an increased risk of stomach cancer.

Menetrier disease (hypertrophic gastropathy)

In this condition, excess growth of the stomach lining causes large folds in the lining and leads to low levels of stomach acid. Because this disease is very rare, it is not known exactly how much this increases the risk of stomach cancer.

Type A blood

Blood type groups refer to certain substances that are normally present on the surface of red blood cells and some other types of cells. These groups are important in matching blood for transfusions. For unknown reasons, people with type A blood have a higher risk of getting stomach cancer.

Inherited cancer syndromes

Some inherited conditions may raise a person’s risk of stomach cancer.

Hereditary diffuse gastric cancer

This inherited syndrome greatly increases the risk of developing stomach cancer. This condition is rare, but the lifetime stomach cancer risk among affected people is about 70% to 80%. Women with this syndrome also have an increased risk of getting a certain type of breast cancer. This condition is caused by mutations (defects) in the CDH1 gene.

Lynch syndrome or hereditary non-polyposis colorectal cancer (HNPCC)

Lynch syndrome (formerly known as HNPCC) is an inherited genetic disorder that increases the risk of colorectal cancer, stomach cancer, and some other cancers. In most cases, this disorder is caused by a defect in either the MLH1 or MSH2 gene, but other genes can cause Lynch syndrome, including MLH3, MSH6, TGFBR2, PMS1, and PMS2.

Familial adenomatous polyposis (FAP)

In FAP, people get many polyps in the colon, and sometimes in the stomach and intestines as well. People with this syndrome are at greatly increased risk of getting colorectal cancer and have a slightly increased risk of getting stomach cancer. It is caused by mutations in the APC gene.

BRCA1 and BRCA2

People who carry mutations of the inherited breast cancer genes BRCA1 or BRCA2 may also have a higher rate of stomach cancer.

Li-Fraumeni syndrome

People with this syndrome have an increased risk of several types of cancer, including developing stomach cancer at a relatively young age. Li-Fraumeni syndrome is caused by a mutation in the TP53 gene.

Peutz-Jeghers syndrome (PJS)

People with this condition develop polyps in the stomach and intestines, as well as in other areas including the nose, the airways of the lungs, and the bladder. The polyps in the stomach and intestines are a special type called hamartomas. They can cause problems like bleeding or blockage of the intestines. PJS can also cause dark freckle-like spots on the lips, inner cheeks and other areas. People with PJS have an increased risk of cancers of the breast, colon, pancreas, stomach, and several other organs. This syndrome is caused by mutations in the gene STK1.

A family history of stomach cancer

People with first-degree relatives (parents, siblings, or children) who have had stomach cancer are more likely to develop this disease.

Some types of stomach polyps

Polyps are non-cancerous growths on the lining of the stomach. Most types of polyps (such as hyperplastic polyps or inflammatory polyps) do not seem to increase a person’s risk of stomach cancer, but adenomatous polyps – also called adenomas – can sometimes develop into cancer.

Epstein-Barr virus (EBV) infection

Epstein-Barr virus causes infectious mononucleosis (also called mono). Almost all adults have been infected with this virus at some time in their lives, usually as children or teens.

EBV has been linked to some forms of lymphoma. It is also found in the cancer cells of about 5% to 10% of people with stomach cancer. These people tend to have a slower growing, less aggressive cancer with a lower tendency to spread. EBV has been found in some stomach cancer cells, but it isn’t yet clear if this virus actually causes stomach cancer.

Certain occupations

Workers in the coal, metal, and rubber industries seem to have a higher risk of getting stomach cancer.

Common variable immune deficiency (CVID)

People with 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, including atrophic gastritis and pernicious anemia. They are also more likely to get gastric lymphoma and stomach cancer.

There are many known risk factors for stomach cancer, but it is not known exactly how these factors cause cells of the stomach lining to become cancerous. This is the subject of ongoing research.

Several changes thought to be pre-cancerous can occur in the stomach lining.

In chronic atrophic gastritis, the normal glands of the stomach are either decreased or absent. There is also some degree of inflammation (the stomach cells are damaged by cells of the immune system). Atrophic gastritis is often caused by H pylori infection. It can also be caused by an autoimmune reaction, in which a person’s immune system attacks the cells lining the stomach. Some people with this condition go on to develop pernicious anemia or other stomach problems, including cancer. It is not known exactly how this condition might progress to cancer.

Another possible pre-cancerous change is intestinal metaplasia. In this condition, the normal lining of the stomach is replaced with cells that closely resemble the cells that usually line the intestine. People with this condition usually have chronic atrophic gastritis as well. How and why this change occurs and progresses to stomach cancer is not well understood. This might also be related to H pylori infection.

Recent research has provided clues on how some stomach cancers form. For instance, H pylori bacteria, particularly certain subtypes, can convert substances in some foods into chemicals that cause mutations (changes) in the DNA of the cells in the stomach lining. This may also explain why certain foods such as preserved meats increase a person’s risk for stomach cancer. On the other hand, some of the foods that might lower stomach cancer risk, such as fruits and vegetables, contain antioxidants that can block substances that damage a cell’s DNA.

Scientists have made a lot of progress in understanding how certain changes in DNA can cause normal stomach cells to grow abnormally and form cancers. DNA is the chemical in cells that carries our genes, which control how our cells function. We look like our parents because they are the source of our DNA. But DNA affects more than how we look.

Some genes control when cells grow and divide into new cells:

• Genes that help cells grow and divide are called oncogenes.
• Genes that help keep cell division under control or cause cells to die at the right time are called tumor suppressor genes.

DNA changes that turn on oncogenes or turn off tumor suppressor genes can cause cancers.

Inherited mutations (abnormal changes) in some genes (as explained in Stomach Cancer Risk Factors ) can increase a person’s stomach cancer risk. These are thought to cause only a small percentage of stomach cancers. Still, genetic testing can be done to look for the gene mutations that can cause some inherited cancer syndromes. You can read more in Genetics and Cancer.

Most of the gene changes that lead to stomach cancer occur after birth. Some of these changes might be caused by risk factors such as H pylori infection or tobacco use. But other gene changes may just be random events that sometimes happen inside cells, without having an outside cause.

There is no sure way to prevent stomach cancer, but there are things you can do that could lower your risk.

Diet, nutrition, body weight, and physical activity

The dramatic decline of stomach cancer in the past several decades is thought to be a result of people reducing many of the known dietary risk factors. This includes greater use of refrigeration for food storage rather than preserving foods by salting, pickling, and smoking. To help reduce your risk, avoid a diet that is high in smoked and pickled foods and salted meats and fish.

A diet high in fresh fruits and vegetables can also lower stomach cancer risk. Citrus fruits (such as oranges, lemons, and grapefruit) may be especially helpful,  but grapefruit and grapefruit juice can change the blood levels of certain drugs you take, so it’s important to discuss this with your health care team before adding grapefruit to your diet.

The American Cancer Society recommends that people eat a healthy diet, with an emphasis on plant foods. This includes eating at least 2½ cups of vegetables and fruits every day. Choosing whole-grain breads, pastas, and cereals instead of refined grains, and eating fish, poultry, or beans instead of processed meat and red meat may also help lower your risk of cancer.

Studies that have looked at using dietary supplements to lower stomach cancer risk have had mixed results so far. Some studies have suggested that combinations of antioxidant supplements (vitamins A, C, and E and the mineral selenium) might reduce the risk of stomach cancer in people with poor nutrition to begin with. But most studies looking at people who have good nutrition have not found any benefit to adding vitamin pills to their diet. Further research in this area is needed.

Although some small studies suggested that drinking tea, particularly green tea, may help protect against stomach cancer, most large studies have not found such a link.

Being overweight or obese may add to the risk of stomach cancer. On the other hand, being physically active may help lower your risk.

The American Cancer Society recommends staying at a healthy weight throughout life by balancing calorie intake with physical activity.  Aside from possible effects on the risk of stomach cancer, losing weight and being active may also have an effect on the risk of several other cancers and health problems. The full recommendations can be found in the American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer Prevention.

Avoiding tobacco use

Tobacco use can increase the risk of cancers of the proximal stomach (the portion of the stomach closest to the esophagus). Tobacco use increases the risk for many other types of cancer and is responsible for about one-third of all cancer deaths in the United States. If you don’t use tobacco, don’t start. If you already do and want help quitting, call the American Cancer Society at 1-800-227-2345.

Treating H pylori infection

It is not yet clear if people whose stomach linings are chronically infected with the H pylori bacteria but who do not have any symptoms should be treated with antibiotics. This is a topic of current research. Some early studies have suggested that giving antibiotics to people with H pylori infection might lower the number of pre-cancerous lesions in the stomach and reduce the risk of developing stomach cancer. But not all studies have found this. More research is needed to be sure that this is a way to prevent stomach cancer in people with H pylori infection.

If your doctor thinks you might have H pylori infection, there are several ways to test for this:

• The simplest way is a blood test that looks for antibodies to H pylori. Antibodies are proteins the body’s immune system makes in response to an infection. A positive H pylori antibody test result can mean either that you are infected with H pylori or that you had an infection in the past that is now cleared.
• Another approach is to have an endoscopy procedure (see Tests for Stomach Cancer) to take a biopsy sample of the stomach lining. This sample can be used for chemical tests for this kind of bacteria. Doctors can also identify H pylori in biopsy samples seen with a microscope. The biopsy sample can also be cultured (placed in a substance that promotes bacterial growth) to see if H pylori grows out of the sample.
• There is also a special breath test for the bacteria. For this test, you drink a liquid containing urea. If H pylori is present, it will chemically change the urea. A sample of your breath is then tested for these chemical changes.

Aspirin use

Using aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen, seems to lower the risk of stomach cancer. These medicines can also lower the risk of developing colon polyps and colon cancer. But they can also cause serious (and even life-threatening) internal bleeding and other potential health risks in some people.

Most doctors consider any reduced cancer risk an added benefit for patients who take these drugs for other reasons, such as to treat arthritis. But doctors do not routinely recommend taking NSAIDs specifically to prevent stomach cancer. Studies have not yet determined for which patients the benefits of lowering cancer risk would outweigh the risks of bleeding complications.

For people at greatly increased risk

Only a small percentage of stomach cancers are known to be caused by hereditary diffuse gastric cancer syndrome. But it's very important to recognize it, because most people who inherit this condition eventually get stomach cancer.  A personal history of invasive lobular breast cancer before age 50 as well as having close family members who have had stomach cancer suggests that they might be at risk for having this syndrome. These people can talk to a genetics professional about getting genetic testing. If the testing shows the person has a mutation (abnormal change) in the CDH1 gene, many doctors will recommend they have their stomach removed before the cancer develops. Another hereditary cancer syndrome with an increased risk for stomach cancer is Lynch syndrome.

Screening is testing for a disease, such as cancer, in people without symptoms. In countries such as Japan, where stomach cancer is very common, mass screening of the population has helped find many cases at an early, curable stage. This may have reduced the number of people who die of this disease, but this has not been proven.

Studies in the United States have not found that routine screening in people at average risk for stomach cancer is useful, because this disease is not that common. On the other hand, people with certain stomach cancer risk factors may benefit from screening.  If you have any questions about your stomach cancer risk or about the benefits of screening, please ask your doctor.

Some of the tests that could be used for screening, such as upper endoscopy, are described in Tests for Stomach Cancer.

Because routine screening for stomach cancer is not done in the United States, most people with this disease are not diagnosed until they have certain signs and symptoms that point to the need for medical tests.

Eating right can be hard for anyone, and may have gotten tougher during cancer treatment. This is especially true for cancers that affect the digestive tract, such as stomach cancer. The cancer or its treatment can affect how you eat and absorb nutrition. Nausea can be a problem during and after some treatments, and you may have lost your appetite and some weight.

If you have lost or are losing weight, or if you are having trouble eating, do the best you can. Eat what appeals to you. Eat what you can, when you can. You might find it helps to eat small portions every 2 to 3 hours until you feel better. Now is not the time to restrict your diet. Try to keep in mind that these problems usually improve over time. Your cancer team may refer you to a dietitian, an expert in nutrition who can give you ideas on how to fight some of the side effects of your treatment.

If part or all of your stomach has been removed, you might need to eat smaller amounts of food more often. Your doctor or nutritionist may also recommend that you stay upright for some time after eating. Your health care team can help you adjust your diet if you are having problems eating.

Some patients with stomach cancer have problems with nausea, diarrhea, sweating, and flushing after eating. This is called dumping syndrome. When part or all of the stomach is removed, the food that is swallowed quickly passes into the intestine, leading to these symptoms after eating. These symptoms often get better over time.

Some people may need nutritional supplements to help make sure they get the nutrition they need. Some people may even need a feeding tube, usually called a jejunostomy tube (or J-tube), put into the small intestine. This is done through a small hole in the skin over the abdomen during a minor operation. A J-tube allows liquid nutrition to be put directly into the small intestine to help prevent weight loss and improve nutrition. Less often, the tube may be placed into the lower part of the stomach instead. This is known as a gastrostomy tube or G-tube.