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stomach-cancer

Stomach Cancer

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What is stomach cancer?

Stomach cancer, also called gastric cancer, is a cancer that starts in the stomach. To understand stomach cancer, it helps to know about the normal structure and function of the stomach.

The stomach : After food is chewed and swallowed, it enters the esophagus, a tube that carries food through the neck and chest to the stomach. The esophagus joins the stomach at the gastroesophageal (GE) junction, which is just beneath the diaphragm (the thin sheet of breathing muscle under the lungs). The stomach is a sac-like organ that holds food and starts to digest it by secreting gastric juice. The food and gastric juice are mixed and then emptied into the first part of the small intestine called the duodenum.

 

 

Some people use the word stomach to refer to the area of the body between the chest and the pelvic area. The medical term for this area is the abdomen. For instance, some people with pain in this area would say they have a “stomachache,” when in fact the pain could be coming from the appendix, small intestine, colon (large intestine), or other organs in the area. Doctors would call this symptom as abdominal pain, because the stomach is only one of many organs in the abdomen.

Stomach cancer should not be confused with other cancers that can occur in the abdomen, like cancer of the colon (large intestine), liver, pancreas, or small intestine because these cancers may have different symptoms, different outlooks, and different treatments.

Parts of the stomach

The stomach has 5 parts:

Cardia: The first portion (closest to the esophagus)

Fundus: The upper part of the stomach next to the cardia.

Body (corpus): The main part of the stomach, between the upper and lower parts

Antrum: The lower portion (near the intestine), where the food is mixed with gastric juice

Pylorus: The last part of the stomach, which acts as a valve to control emptying of the stomach contents into the small intestine.

The first 3 parts of the stomach (cardia, fundus, and body) are sometimes called the proximal stomach. Some cells in these parts of the stomach make acid and pepsin (a digestive enzyme), the parts of the gastric juice that help digest food. They also make a protein called intrinsic factor, which the body needs to absorb vitamin B12.

The lower 2 parts (antrum and pylorus) are called the distal stomach.

The stomach has 2 curves, which form its inner and outer borders. They are called the lesser curvature and greater curvature, respectively.

Other organs next to the stomach include the colon, liver, spleen, small intestine, and pancreas.

The stomach wall has 5 layers:

The innermost layer is the mucosa. This is where stomach acid and digestive enzymes are made. Most stomach cancers start in this layer.

Next is a supporting layer called the submucosa.

Outside of this is the muscularis propria, a thick layer of muscle that moves and mixes the stomach contents.

The outer 2 layers, the subserosa and the outermost serosa, wrap the stomach.

The layers are important in determining the stage (extent) of the cancer and in helping to determine a person’s prognosis (outlook). As a cancer grows from the mucosa into deeper layers, the stage becomes more advanced and the prognosis is not as good.

Development of stomach cancer

Stomach cancers tend to develop slowly over many years. Before a true cancer develops, pre-cancerous changes often occur in the inner lining (mucosa) of the stomach. These early changes rarely cause symptoms and therefore often go undetected.

Cancers starting in different sections of the stomach may cause different symptoms and tend to have different outcomes. The cancer’s location can also affect the treatment options. For example, cancers that start at the GE junction are staged and treated the same as cancers of the esophagus. A cancer that starts in the cardia of the stomach but then grows into the GE junction is also staged and treated like a cancer of the esophagus. (For more information, see our document, Esophagus Cancer.)

Stomach cancers can spread (metastasize) 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. Lymph nodes are 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 to organs such as the liver, lungs, and bones. If cancer has spread to the lymph nodes or to other organs, the patient’s outlook is not as good.

Types of stomach cancers

Different types of stomach cancer include:

Adenocarcinoma : About 90% to 95% of cancers of the stomach are adenocarcinomas. When the term stomach cancer or gastric cancer is used, it almost always refers to an adenocarcinoma. These cancers develop from the cells that form the innermost lining of the stomach (known as the mucosa).

Lymphoma : These are cancers of the immune system tissue that are sometimes found in the wall of the stomach. About 4% of stomach cancers are lymphomas. The treatment and outlook depend on the type of lymphoma. For more detailed information, see our document, Non-Hodgkin Lymphoma.

Gastrointestinal stromal tumor (GIST) : These are rare tumors that start in very early forms of cells in the wall of the stomach called interstitial cells of Cajal. Some of these tumors are non-cancerous (benign); others are cancerous. Although GISTs can be found anywhere in the digestive tract, most are found in the stomach. For more information, see our document, Gastrointestinal Stromal Tumor (GIST).

Carcinoid tumor : These are tumors that start in hormone-making cells of the stomach. Most of these tumors do not spread to other organs. About 3% of stomach cancers are carcinoid tumors. These tumors are discussed in more detail in our document, Gastrointestinal Carcinoid Tumors.

Other cancers : Other types of cancer, such as squamous cell carcinoma, small cell carcinoma, and leiomyosarcoma, can also start in the stomach, but these cancers are very rare.

What are the risk factors for stomach cancer?

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 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.

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 the age of 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, 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 (chronic atrophic gastritis) and pre-cancerous changes of the inner lining of the stomach .

Patients 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. 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 CDH1gene. Some cancer centers can test for these gene mutations.

Hereditary non-polyposis colorectal cancer (HNPCC) : HNPCC, also known as Lynch syndrome, is an inherited genetic disorder that increases the risk of colorectal cancer. People with this syndrome also have an increased risk of getting stomach cancer (as well as 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 HNPCC, including MLH3, MSH6, TGFBR2, PMS1, and PMS2.

Familial adenomatous polyposis (FAP) : In FAP syndrome, 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 calledhamartomas. 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.

Most cancers are caused by gene changes that happen during a person’s lifetime, but a person’s cancer risk can be higher if they have one of these rare inherited mutations. Doctors can test for certain kinds of gene changes that make a person more likely to get cancer. You can read more in our document, Genetic Testing: What You Need to Know.

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.

Do we know what causes 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.

During the past few years, 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 each cell that carries our genes — the instructions for 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 help cells grow and divide into new cells. They are called oncogenes. Others that slow down cell division, cause cells to die at the right time, or help fix DNA damage are called tumor suppressor genes. Cancers can be caused by DNA changes that turn on oncogenes or turn off tumor suppressor genes.

Inherited changes in some of these types of genes (as explained in the section “What are the risk factors for stomach cancer?”) can increase a person’s stomach cancer risk. But inherited gene changes are responsible for only a small percentage of stomach cancers.

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 external cause.

Can stomach cancer be prevented?

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.

Doctors recommends maintaining 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.

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.

Treating H pylori infection :  It is not yet clear whether 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 may lower the number of pre-cancerous lesions in the stomach and may 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 the section “How is stomach cancer diagnosed?”) 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 viewed under 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 caused by hereditary diffuse gastric cancer syndrome. But it is very important to recognize it, because most people who inherit this condition eventually get stomach cancer. People with a strong family history of stomach cancer should find out if they might have it. If their family history suggests that they might, they can get genetic testing. If the testing shows the person has an abnormal form of the CDH1 gene, many doctors will recommend they have their stomach removed before the cancer develops.

Not all stomach cancers can be prevented

Avoiding risk factors when possible might lower a person’s stomach cancer risk, but it cannot guarantee a person will not get this disease. Early detection may be the best way to improve the chance of successful treatment and reduce the number of deaths caused by stomach cancer, particularly in countries where it is common, and in people with certain inherited syndromes and medical conditions that strongly increase stomach cancer risk.

Can stomach cancer be found early?

Screening is the search for 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 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 the section, “How is stomach cancer diagnosed?”

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

How is stomach cancer diagnosed?

Stomach cancers are usually found when a person goes to the doctor because of signs or symptoms they are having. If stomach cancer is suspected, tests will be needed to confirm the diagnosis.

Signs and symptoms of stomach cancer

Unfortunately, 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

Most of these symptoms are more likely to be caused by things other than cancer, such as a stomach virus. 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.

Medical history and physical exam

When taking your medical history, the doctor will ask you questions about your symptoms (eating problems, pain, bloating, etc.) and possible risk factors to see if they might suggest stomach cancer or another cause. The physical exam gives your doctor information about your general health, possible signs of stomach cancer, and other health problems. In particular, the doctor will feel your abdomen for 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 specializes in diseases of the digestive tract, who will examine you and do further testing.

Upper endoscopy: Upper endoscopy (also called esophagogastroduodenoscopy or EGD) is the main test used to find stomach cancer. It may be used when someone has certain risk factors or when signs and symptoms suggest this disease may be present.

During this test, you are sedated (made sleepy). The doctor passes an endoscope, which is a thin, flexible, lighted tube with a small video camera on the end, down your throat. This lets the doctor see the lining of your esophagus, stomach, and first part of the small intestine. If abnormal areas are seen, biopsies (tissue samples) can be taken using instruments passed through the endoscope. The tissue samples are sent to a lab, where they are looked at under a microscope to see if cancer is present.

When seen through an endoscope, stomach cancer can look like an ulcer, a mushroom-shaped or protruding mass, or diffuse, flat, thickened areas of mucosa known as linitis plastica.

Endoscopy can also be used as part of a special imaging test known as endoscopic ultrasound, which is described below.

Biopsy : Your doctor may suspect cancer if an abnormal-looking area is seen on endoscopy or an imaging test, but the only way to tell for sure if it is really cancer is by doing a biopsy. During a biopsy, the doctor removes a sample of the abnormal area.

Biopsies to check for stomach cancer are most often obtained during upper endoscopy. If the doctor sees any abnormal areas in the stomach lining during the endoscopy, instruments can be passed down the endoscope to biopsy them.

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 areas of possible cancer spread, such as nearby lymph nodes or suspicious areas in other parts of the body.

Testing biopsy samples: Biopsy samples are sent to a lab to be looked at under a microscope. The samples are checked to see if they contain cancer, and if they do, what kind it is (for example, adenocarcinoma, carcinoid, gastrointestinal stromal tumor, or lymphoma).

If a sample contains adenocarcinoma cells, it may be tested to see if it has too much of a growth-promoting protein called HER2/neu (often just shortened to HER2). The HER2/neu gene instructs the cells to make this protein. Tumors with increased levels of HER2/neu are called HER2-positive.

Stomach cancers that are HER2-positive can be treated with drugs that target the HER2/neu protein, such as trastuzumab (Herceptin®). See the section, “Targeted therapies for stomach cancer” for more information.

The biopsy sample may be tested in 2 different ways:

Immunohistochemistry (IHC): In this test, special antibodies that stick to the HER2/neu protein are applied to the sample, which cause cells to change color if many copies are present. This color change can be seen under a microscope. The test results are reported as 0, 1+, 2+, or 3+.

Fluorescent in situ hybridization (FISH): This test uses fluorescent pieces of DNA that specifically stick to copies of the HER2/neu gene in cells, which can then be counted under a special microscope.

Often the IHC test is used first.

If the results are 0 or 1+, the cancer is HER2-negative. People with HER2-negative tumors are not treated with drugs (like trastuzumab) that target HER2.

If the test comes back 3+, the cancer is HER2-positive. Patients with HER2-positive tumors may be treated with drugs like trastuzumab.

When the result is 2+, the HER2 status of the tumor is not clear. This often leads to testing the tumor with FISH.

See Testing Biopsy and Cytology Specimens for Cancer to learn more about different types of biopsies and tests, how the tissue is used in the lab to diagnose cancer, and what the results will tell you.

Imaging tests

Imaging tests use x-rays, magnetic fields, sound waves, or radioactive substances to create pictures of the inside of your body. Imaging tests may be done for a number of reasons, including:

To help find out whether a suspicious area might be cancerous

To learn how far cancer may have spread

To help determine if treatment has been effective

Upper gastrointestinal (GI) series

This is an x-ray test to look at the inner lining of the esophagus, stomach, and first part of the small intestine. This test is used less often than endoscopy to look for stomach cancer or other stomach problems, as it may miss some abnormal areas and does not allow the doctor to take biopsy samples. But it is less invasive than endoscopy, and it might be useful in some situations.

For this test, the patient drinks a white chalky solution containing a substance called barium. The barium coats the lining of the esophagus, stomach, and small intestine. Several x-ray pictures are then taken. Because x-rays can’t pass through the coating of barium, this will outline any abnormalities of the lining of these organs.

A double-contrast technique may be used to look for early stomach cancer. With this technique, after the barium solution is swallowed, a thin tube is passed into the stomach and air is pumped in. This makes the barium coating very thin, so even small abnormalities will show up.

Endoscopic ultrasound : Ultrasound uses sound waves to produce images of organs such as the stomach. During a standard ultrasound, a transducer, which is a wand-shaped probe, is placed on the skin. It gives off sound waves and detects the echoes as they bounce off internal organs. The pattern of echoes is processed by a computer to produce a black and white image on a screen.

In endoscopic ultrasound (EUS), a small transducer is placed on the tip of an endoscope. The endoscope is passed down the throat and into the stomach while the patient is sedated. This lets the transducer rest directly on the wall of the stomach where the cancer is. 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. The picture quality is better than a standard ultrasound because of the shorter distance the sound waves have to travel.

EUS is most useful in seeing how far a cancer may have spread into the wall of the stomach, to nearby tissues, and to nearby lymph nodes. It can also be used to help guide a needle into a suspicious area to get a tissue sample (EUS-guided needle biopsy).

Computed tomography (CT or CAT) scan : The CT scan is an x-ray test that produces detailed cross-sectional images of your body. Instead of taking one picture, like a standard x-ray, a CT scanner takes many pictures as it rotates around you. A computer then combines these pictures into images of slices of the part of your body being studied.

Before the test, you may be asked to drink 1 or 2 pints of a contrast solution and/or receive an intravenous (IV) line through which a contrast dye is injected. This helps better outline structures in your body.

The IV contrast can cause some flushing (redness and warm feeling). Some people are allergic and get hives, or rarely have more serious reactions like trouble breathing and low blood pressure. Be sure to tell the doctor if you have any allergies or have ever had a reaction to any contrast material used for x-rays.

A CT scanner has been described as a large donut, with a narrow table that slides in and out of the middle opening. 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.

CT scans show the stomach fairly clearly and often can confirm the location of the cancer. CT scans 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. The CT scan can help determine the extent (stage) of the cancer and whether surgery may be a good treatment option.

CT-guided needle biopsy: CT scans can also be used to guide a biopsy needle into a suspected area of cancer spread. The patient remains on the CT scanning table while a doctor moves a biopsy needle through the skin toward the mass. CT scans are repeated until the needle is within the mass. A fine-needle biopsy sample (tiny fragment of tissue) or a core-needle biopsy sample (a thin cylinder of tissue) is then removed and looked at under a microscope.

Magnetic resonance imaging (MRI) scan : MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed by the body and then released in a pattern formed by the type of body tissue and by certain diseases. A computer translates the pattern into a very detailed image of parts of the body. A contrast material might be injected just as with CT scans, but this is used less often.

Most doctors prefer to use CT scans to look at the stomach. But an MRI may sometimes provide 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 is confining and can upset people with a fear of enclosed spaces. Special, open MRI machines can help with this if needed, although the images may not be as sharp in some cases. The MRI machine makes loud buzzing noises that you may find disturbing. Some places provide headphones to block this noise out.

Positron emission tomography (PET) scan : In this test, radioactive substance (usually a type of sugar related to glucose, known as FDG) is injected into a vein. (The amount of radioactivity used is very low and will pass out of the body over the next day or so.) Because cancer cells are growing faster than normal cells, they use sugar much faster, so they take up the radioactive material. 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 picture of areas of radioactivity in the body.

PET is sometimes useful if your doctor thinks the cancer might have spread but doesn’t know where. The picture is not finely detailed like a CT or MRI scan, but it provides helpful information about the whole body. This test can be useful for spotting cancer that has spread beyond the stomach and wouldn’t be treatable by surgery.

Some machines can do both a PET and CT scan at the same time (PET/CT scan). This lets the doctor compare areas of higher radioactivity on the PET with the more detailed appearance of that area on the CT.

PET scans and PET/CT can 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. Before having this test, ask your doctor if the results could potentially change your treatment plan.

Chest x-ray : This test can help find out if the cancer has spread to the lungs. It might also determine if there are any serious lung or heart diseases present. This test is not needed if a CT scan of the chest has been done..

Laparoscopy : If this procedure is done, it is usually only after stomach cancer has already been found. Although CT or MRI scans can create detailed pictures of the inside of the body, they can miss some tumors, especially if they are very small. Doctors might do a laparoscopy before any other surgery to help confirm a stomach cancer is still only in the stomach and can be removed completely with surgery.

This procedure is done in an operating room with the patient under general anesthesia (in a deep sleep). A laparoscope (a thin, flexible tube) is inserted through a small surgical opening in the patient’s side. The laparoscope has a small video camera on its end, which sends pictures of the inside of the abdomen to a TV screen. Doctors can look closely at the surfaces of the organs and nearby lymph nodes, or even take small samples of tissue or of fluid in the abdomen (called peritoneal washings) to make sure the cancer hasn’t spread and that all the cancer can be removed. Sometimes laparoscopy is combined with ultrasound to give a better picture of the cancer.

Lab tests : When looking for signs of stomach cancer, a doctor may order a blood test called a complete blood count (CBC) to look for anemia (which could be caused by internal bleeding). A fecal occult blood test may be done to look for blood in stool (feces).

The doctor might recommend other tests if cancer is found, especially if you are going to have surgery. For instance, blood tests will be done to make sure your liver and kidney functions are normal. If surgery is planned or you are going to get medicines that can affect the heart, you may also have an electrocardiogram (EKG) and echocardiogram (an ultrasound of the heart) to make sure your heart is functioning well.

How is stomach cancer staged?

The stage of a cancer is a description of how far the cancer has spread. The stomach cancer’s stage is an important factor in choosing treatment options and predicting a patient’s outlook (prognosis).

There are actually 2 types of stages for stomach cancer.

The clinical stage of the cancer is the doctor’s best estimate of the extent of the cancer, based on the results of physical exams, endoscopy, biopsies, and any imaging tests (such as CT scans) that have been done. These exams and tests are described in the section “How is stomach cancer diagnosed?”

If surgery is done, the pathologic stage can be determined using the same test results used for the clinical stage, plus what is found from tissues removed during surgery.

The clinical stage is used to help plan treatment. Sometimes, though, the cancer has spread further than the clinical stage estimates. Because the pathologic stage is based on what was found at surgery, it can more accurately predict the patient’s outlook. The staging described here is the pathologic stage.

A staging system is a way for members of the cancer care team to describe the extent of a cancer’s spread. The system most often used to stage stomach cancer in the United States is the American Joint Commission on Cancer (AJCC) TNM system. The TNM system for staging contains 3 key pieces of information:

T describes the extent of the primary tumor (how far it has grown into the wall of the stomach and into nearby organs).

N describes the spread to nearby (regional) lymph nodes.

M indicates whether the cancer has metastasized (spread) to distant parts of the body. The most common sites of distant spread of stomach cancer are the liver, the peritoneum (the lining of the space around the digestive organs), and distant lymph nodes. Less common sites of spread include the lungs and brain.

Numbers or letters appear after T, N, and M to provide more details about each of these factors:

The numbers 0 through 4 indicate increasing severity.

The letter X means “cannot be assessed” because the information is not available.

The letters “is” refer to carcinoma in situ, which means the tumor is only in the top layer of mucosa cells and has not yet invaded deeper layers of tissue.

This system is for staging all stomach cancers except those starting in either the gastroesophageal junction (where the stomach and the esophagus meet) or in the cardia (the first part of the stomach) and growing into the gastroesophageal junction. Those cancers are staged (and often treated) like cancers of the esophagus.

T categories of stomach cancer

Nearly all stomach cancers start in the innermost layer of the stomach wall (the mucosa). The T category describes how far through the stomach’s 5 layers the cancer has invaded.

The innermost layer is the mucosa. The mucosa has 3 parts: epithelial cells, which lie on top of a layer of connective tissue (the lamina propria), which is on top of a thin layer of muscle (the muscularis mucosa).

Under the mucosa is a supporting layer called the submucosa.

Below this is the muscularis propria, a thick layer of muscle that moves and mixes the stomach contents.

The next 2 layers, the subserosa and the outermost serosa, act as wrapping layers for the stomach.

TX: The main (primary) tumor cannot be assessed.

T0: No signs of a main tumor can be found.

Tis: Cancer cells are only in the top layer of cells of the mucosa (innermost layer of the stomach) and have not grown into deeper layers of tissue such as the lamina propria or muscularis mucosa. This stage is also known as carcinoma in situ.

T1: The tumor has grown from the top layer of cells of the mucosa into the next layers below such as the lamina propria, the muscularis mucosa, or submucosa.

T1a: The tumor is growing into the lamina propria or muscularis mucosa.

T1b: The tumor has grown through the lamina propria and muscularis mucosa and into the submucosa.

T2: The tumor is growing into the muscularis propria layer.

T3: The tumor is growing into the subserosa layer.

T4: The tumor has grown into the serosa and may be growing into a nearby organ (spleen, intestines, pancreas, kidney, etc.) or other structures such as major blood vessels.

T4a: The tumor has grown through the stomach wall into the serosa, but the cancer hasn’t grown into any of the nearby organs or structures.

T4b: The tumor has grown through the stomach wall and into nearby organs or structures.

N categories of stomach cancer

NX: Nearby (regional) lymph nodes cannot be assessed.

N0: No spread to nearby lymph nodes.

N1: The cancer has spread to 1 to 2 nearby lymph nodes.

N2: The cancer has spread to 3 to 6 nearby lymph nodes.

N3: The cancer has spread 7 or more nearby lymph nodes.

N3a: The cancer has spread to 7 to 15 nearby lymph nodes.

N3b: The cancer has spread to 16 or more nearby lymph nodes.

M categories of stomach cancer

M0: No distant metastasis (the cancer has not spread to distant organs or sites, such as the liver, lungs, or brain).

M1: Distant metastasis (the cancer has spread to organs or lymph nodes far away from the stomach).

TNM stage grouping

Once the T, N, and M categories have been determined, this information is combined and expressed as a stage, using the number 0 (zero) and the Roman numerals I through IV. This is known as stage grouping. Some stages are split into substages, indicated by letters.

Stage 0: Tis, N0, M0 : This is stomach cancer in its earliest stage. It has not grown beyond the inner layer of cells that line the stomach (Tis). The cancer has not spread to any lymph nodes (N0) or anywhere else (M0). This stage is also known ascarcinoma in situ.

Stage IA: T1, N0, M0 :  The cancer has grown beneath the top layer of cells in the mucosa into tissue below, such as the connective tissue (lamina propria), the thin muscle layer (muscularis mucosa), or the submucosa (T1). The cancer has not spread to any lymph nodes (N0) or anywhere else (M0).

Stage IB: Any of the following: 

T1, N1, M0: The cancer has grown into the layer of connective tissue (lamina propria), and may have grown into the thin layer of muscle beneath it (muscularis mucosa) or deeper into the submucosa (T1). Cancer has also spread to 1 or 2 lymph nodes near the stomach (N1), but not to any distant tissues or organs (M0).

OR

T2, N0, M0: The cancer has grown into the main muscle layer of the stomach wall, called the muscularis propria (T2). It has not spread to nearby lymph nodes (N0) or to any distant tissues or organs (M0).

Stage IIA: Any of the following:

T1, N2, M0: The cancer has grown beneath the top layer of cells of the mucosa into the layer of connective tissue (lamina propria), thin muscle layer (muscularis mucosa), or the submucosa (T1). It has spread to 3 to 6 nearby lymph nodes (N2). It has not spread to distant sites (M0).

OR

T2, N1, M0: The cancer has grown into the main muscle layer of the stomach called the muscularis propria (T2). It has spread to 1 or 2 nearby lymph nodes (N1), but has not spread to distant sites (M0).

OR

T3, N0, M0: The cancer has grown through the main muscle layer into the subserosa, but has not grown through all the layers to the outside the stomach (T3). It has not spread to any nearby lymph nodes (N0) or to distant tissues or organs (M0).

Stage IIB: Any of the following:

T1, N3, M0: The cancer has grown beneath the top layer of cells of the mucosa into the layer of connective tissue (lamina propria), the thin muscle layer, or the submucosa (T1). It has spread to 7 or more nearby lymph nodes (N3). It has not spread to distant tissues or organs (M0).

OR

T2, N2, M0: The cancer has grown into the main muscle layer, called the muscularis propria (T2). It has spread to 3 to 6 nearby lymph nodes (N2), but it has not spread to distant tissues or organs (M0).

OR

T3, N1, M0: The cancer has grown into the subserosa layer, but not through all the layers to the outside of the stomach (T3). It has spread to 1 or 2 nearby lymph nodes (N1), but has not spread to distant tissues or organs (M0).

OR

T4a, N0, M0: The cancer has grown completely through all the layers of stomach wall into the outer covering of the stomach (the serosa), but it has not grown into nearby organs or tissues, such as the spleen, intestines, kidneys, or pancreas (T4a). It has not spread to any nearby lymph nodes (N0) or distant sites (M0).

Stage IIIA: Any of the following:

T2, N3, M0: The cancer has grown into the main muscle layer, called

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