What Is Stomach Cancer?
Stomach cancer (also called gastric cancer) starts in the stomach.
After food has been chewed and swallowed, it passes down a tube called the esophagus and empties 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 can all vary depending on where the cancer begins.
The stomach itself is made up of 5 layers. Starting from the inside and working out:
The innermost layer is called the mucosa - This is where the stomach acid and digestive juices are made
Next is a supporting layer called the submucosa
This is surrounded by the muscularis, a layer of muscle that moves and mixes the stomach contents.
The next 2 layers, the subserosa and the serosa (the outermost layer) act as wrapping for the stomach.
Most of the time stomach cancer starts in the mucosa .
Stomach cancer probably grows slowly over many years. Before a true cancer develops, there are usually changes that take place in the lining of the stomach. These early changes rarely produce symptoms and therefore often are not noticed.
Stomach cancer can spread in several different ways.
It can grow through the wall of the stomach and eventually grow into nearby organs.
It can also spread to the lymph nodes and then through the lymph system. If cancer spreads this way, the outlook for a cure gets worse.
When stomach cancer is more advanced, it can travel through the bloodstream and form deposits of cancer cells in organs such as the liver, lungs, and bones.
Most cancers of the stomach are of a type called adenocarcinomas . This cancer develops from cells that form the lining of the innermost layer, the mucosa. The term “stomach cancer” almost always refers to this type of cancer.
Lymphomas, gastric stromal tumors, and carcinoid tumors are other, much less common, tumors that are found in the stomach.
How Many People Get Stomach Cancer?
We know that there will be about 22,280 new cases of stomach cancer in the United States in 2006.
About 11,430 people will die of this disease.
Two thirds of the people found to have stomach cancer are older than 65.
The risk of a person getting stomach cancer in their lifetime is about 1 in 100.
Stomach cancer is much more common in some countries other than the United States. It was once a leading cause of cancer deaths in this country but it is now much less common. The reasons for this decline are not completely known, but they may be linked to more use of refrigeration for food storage and less use of salted and smoked foods. Some doctors think that an important factor is the use of antibiotics to treat infections in children. These drugs can kill the bacteria (Helicobacter pylori) that may be a major cause of this disease.
What Causes Stomach Cancer?
Scientists have found several risk factors that make a person more likely to develop stomach cancer.
The major risk factors for stomach cancer are listed below:
Bacteria infection: Many doctors think that infection with bacteria called Helicobacter pylori may be a major cause of stomach cancer. Long-term infection with this germ can lead to inflammation and damage to the inner layer of the stomach, a possible pre-cancerous change. This bacterium is also linked to some types of lymphoma of the stomach. But most people who carry this germ in their stomachs never develop cancer.
Diet: An increased risk of stomach cancer is linked to diets high in smoked foods, salted fish and meats, and pickled vegetables. On the other hand, eating whole grain products and fresh fruits and vegetables that contain vitamins A and C appears to lower the risk of stomach cancer.
Tobacco and alcohol abuse: Smoking just about doubles the risk of stomach cancer for smokers. While some studies have linked alcohol use to stomach cancer, this is not certain.
Obesity: Being very overweight (obese) is a major cause of many cancers, including cancer of the stomach.
Earlier stomach surgery: Stomach cancer is more likely to occur in people who have had part of their stomach removed to treat other problems such as ulcers.
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 anemia (a shortage of red blood cells). Patients with this disease also have a slightly increased risk of stomach cancer.
Menetrier disease: This rare disease involves changes in the stomach lining that in turn are linked to a risk of stomach cancer.
Gender: Stomach cancer is more than twice as common in men as it is in women.
Ethnicity: The rate of stomach cancer is higher in Hispanics and African Americans than in non-Hispanic whites. The highest rates are seen in Asian/Pacific Islanders.
Age: There is a sharp increase in stomach cancer after the age of 50.
Type A blood: For unknown reasons, people with type A blood have a higher risk of getting stomach cancer.
Family history: People with several close relatives who have had stomach cancer are more likely to develop this disease. Also, some families have a gene change (mutation) that puts them at greater risk for getting colorectal cancer and a slightly higher risk of stomach cancer.
Stomach polyps: Polyps are small mushroom-like growths of the lining of the stomach. Most types of polyps do not increase the risk of stomach cancer. But one type (adenomatous polyps) sometimes develops into stomach cancer.
Geography: Stomach cancer is most common in Japan, China, Southern and Eastern Europe, and South and Central America. This disease is less common in Northern and Western Africa, Melanesia, South Central Asia, and North America.
Epstein-Barr virus: This virus causes “mono” (infectious mononucleosis). It has been found in the stomach cancers of some people.
While there are many risk factors for stomach cancer, we do not know exactly how these factors cause cells of the stomach to become cancerous. 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 grow abnormally and form cancers. Most of the gene changes that are linked to stomach cancer take place after birth. Only a very few are inherited.
How Is Stomach Cancer Found?
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 benefits 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:
unintended weight loss and lack of appetite
pain in the area of the stomach (abdominal pain)
vague discomfort in the abdomen, often above the navel
a sense of fullness just below the chest bone after eating a small meal
heartburn, indigestion, or ulcer-type symptoms
nausea
vomiting, with or without blood
swelling of the abdomen
Of course, many of these symptoms can be caused by conditions other than cancer. But if you have any of these problems and they don’t go away, you should check with your doctor.
What Tests Will be Performed If Cancer Is Suspected ?
If there is any reason to suspect stomach cancer, your doctor will ask you questions about risk factors and symptoms and do a complete physical exam. The doctor will feel your abdomen to see if there is any swelling that might mean a tumor.
You may need to have further tests to find out if the disease is really present and if so, to see how far it has spread. Here are some of the tests that might be done.
Upper endoscopy : In this test, a thin, flexible, lighted tube (called an endoscope) is placed down the patient’s throat. With this tube, the doctor can see the lining of the esophagus, stomach, and the first part of the small intestine. If anything looks not normal, tissue samples can be removed. These samples are looked at under a microscope to see if cancer is present and, if so, what type of cancer it is. A person having this test is made sleepy (sedated) before it starts, so there should be no discomfort.
Upper GI (gastrointestinal) series: People having this test drink a liquid containing barium that coats the lining of the esophagus, stomach, and first part of the small intestine. Then several x-rays are taken. Sometimes after drinking the liquid, the person swallows baking soda crystals, which creates air in the stomach. This makes the barium coating very thin so that even small abnormalities will show up.
Ultrasound: For this test, sound waves are used to produce pictures of internal organs. Most people know about ultrasound because it is used to create a picture of the baby during pregnancy. Ultrasound can also be done with a probe placed into the stomach through the mouth or nose. In this case, it can help tell how far the cancer has spread within the stomach or into nearby tissues and lymph nodes.
CT scan (computed tomography): This test uses a special x-ray machine that takes pictures from many angles. The pictures are combined by a computer to produce detailed cross-sectional images. The CT scan can help show if and where stomach cancer has spread. It can also be used to guide a biopsy needle into an area that might be cancer. The needle is used to take a small sample of tissue for testing in the lab.
CT scans take longer than regular x-rays and you need to lie still on a table while they are being done. You may also have an IV (intravenous) line through which a contrast "dye" is injected.
PET scan (positron emission tomography): In this test, a special kind of radioactive sugar is injected into the patient’s vein. The sugar collects in areas that have cancer and a scanner can spot these areas. This test is useful for finding cancer that has spread beyond the stomach. It may also help in staging the cancer (see below).
MRI scan (magnetic resonance imaging): Like CT scans, MRIs display a cross-section of the body. But MRI uses powerful magnets instead of radiation. MRI scans also take longer than CT scans—often up to an hour. A contrast dye might be injected just as with CT scans, but is used less often. Most doctors prefer to use CT scans, but sometimes an MRI can provide more information.
Chest x-rays: These can be used to tell if the cancer has spread to the lungs.
Laparoscopy : A thin, flexible tube is placed into the patient’s side through a small incision and transmits a picture of the inside of the abdomen to a video screen. The doctor can use this before surgery to see if all cancer can be removed and to spot spread of the cancer.
Lab tests: These may include a blood test called a complete blood count (CBC) to look for anemia, and a fecal occult blood test, which looks for small amounts of blood in the stool.
Staging
Staging is the process of finding out how far the cancer has spread. This is very important because the treatment and the outlook for your recovery depend on the stage of the cancer.
After stage 0 (cancer that has not grown beyond the layer of cells that line the stomach), stages are labeled using Roman numerals I through IV (1-4). In general, the lower the number, the less the cancer has spread. A higher number, such as stage IV (4), means a more serious cancer.
After looking at your test results, the doctor will tell you the stage of your cancer. Be sure to ask your doctor to explain your stage in a way you understand. This will help you both decide on the best treatment for you
How Is Stomach Cancer Treated?
No matter what stage of stomach cancer you have, there is treatment. The choice of treatment you receive depends on many factors. The place and stage of the tumor are very important, of course. But other factors include your age, your overall health, and your personal wishes.
The main treatments for stomach cancer are
surgery
chemotherapy
radiation therapy
Often the best approach involves using 2 or more of these treatment methods. Your recovery is one goal of your cancer care team. If a cure is not possible, treatment is aimed at relieving symptoms such as trouble eating, pain, or bleeding. Before you start treatment it is important that you understand the goal of your treatment-- whether it is to cure or to relieve symptoms.
Surgery
Depending on the type and stage of your cancer, surgery might be used to remove the cancer and that part of the stomach where it is attached. The surgeon will try to leave behind as much normal stomach as possible.
At this time, surgery is the only way to cure stomach cancer. If you have stage 0, I, II, or IIII cancer, and if you are healthy enough, an attempt should be made to treat the cancer by completely removing it.
Even if the cancer is too widespread to be completely removed by surgery, an operation could help prevent bleeding from the tumor or keep the stomach from becoming blocked. This type of surgery is known as palliative, meaning that it relieves or prevents symptoms but is not expected to cure the cancer.
There are 3 main types of surgery for stomach cancer .
Endoscopic mucosal resection : Resection refers to the removal of a tumor or part of an organ by cutting it out. With this method, the cancer is removed through the endoscope. This can be done only for very early cancers where the chance of spread to the lymph nodes is very low.
Subtotal (partial) gastrectomy : This approach can be used if the cancer is in the lower part of the stomach close to the intestines. Only part of the stomach is removed, sometimes along with the first part of the small intestine. Eating is much easier with this approach rather than when the whole stomach is removed.
Total gastrectomy: This method is used if the cancer is in the middle or upper part of the stomach. The surgeon removes the entire stomach. Because the stomach holds and digests food, when it is removed a person will fill up after only a few mouthfuls. To solve this problem, the surgeon will try to make a new "stomach" out of intestinal tissue. No matter how effective this is, people who have had a total gastrectomy can only eat a small amount of food at a time. Because of this, they must eat more often.
If surgery is done to cure the cancer, the lymph nodes and some of the fatty tissue (omentum) around the stomach are removed as well. If the cancer has spread beyond the stomach to the spleen, it will be removed too.
Many surgeons believe that the chances of a cure are better if all of the lymph nodes near the stomach are removed. But it usually takes a skilled surgeon with experience in operating on stomach cancer to do this. It is important to ask your surgeon about his or her experience in operating on stomach cancer. Because stomach cancer can also spread to lymph nodes that are farther away in the abdomen, some doctors believe that these also must be removed. But not all doctors agree.
Surgery for stomach cancer is very hard to do and can lead to serious problems. These could include:
bleeding from the surgery
blood clots
damage during the operation to nearby organs such as the gallbladder and the pancreas
Rarely, the new connections between the ends of the stomach and esophagus or small intestine may not hold together completely and leak. Such complications, which could be fatal, were more common in the past. Today, only about 1% to 2% of people die after this surgery.
Other side effects may develop after recovery from surgery. These could include
heartburn
abdominal pain, especially after eating
shortages of some vitamins.
The stomach is important in helping the body absorb certain vitamins. If some parts of the stomach are removed, the doctor will prescribe vitamin supplements. Some of these can only be taken by injection. After stomach surgery, most people will need to change their diets, eating smaller, more frequent meals.
It is crucial to talk to your doctor about the surgery you are going to have. Some surgeons try to leave behind as much of the stomach as they can so that patients will have fewer problems later. But the tradeoff is that the cancer might be more likely to come back.
Chemotherapy
Chemotherapy refers to the use of drugs to kill cancer cells. Usually the drugs are given into a vein or by mouth. Once the drugs enter the bloodstream, they spread throughout the body. Chemotherapy is useful in treating cancer that has spread.
Chemotherapy may be used as the main treatment for stomach cancer that has spread to distant organs. It is being studied as an added treatment given either before or after surgery. So far, studies have found that chemotherapy may help relieve symptoms for some people, especially those whose cancer has spread to other areas of the body. There is also some evidence that chemotherapy together with radiation therapy may delay the cancer coming back and extend the life of people with advanced stomach cancer.
While chemotherapy drugs kill cancer cells, they also damage some normal cells and this can lead to side effects. These side effects depend on the type of drugs used, the amount given, and the length of treatment. You could experience some of these temporary side effects:
fatigue
nausea and vomiting
diarrhea
loss of appetite
hair loss (it grows back after treatment ends)
mouth sores
a higher risk of infection caused by a shortage of white blood cells
bruising or bleeding after minor cuts caused by a shortage of blood platelets
shortness of breath from low red blood cell counts
Most of these side effects go away when treatment is over. If you have any problems with side effects, be sure to tell your doctor or nurse, as there are often ways to help.
Radiation Therapy
Radiation therapy is treatment with high-energy rays (such as x-rays) to kill or shrink cancer cells. Radiation coming from a machine outside the body (external radiation) is the type often used to treat stomach cancer.
After surgery, radiation therapy can be used to kill very small areas of cancer that cannot be seen and removed during surgery. Some studies suggest that radiation, especially when combined with chemotherapy, can delay or prevent the cancer from coming back after surgery and may help people to live longer. Radiation can also be used to ease symptoms such as pain, bleeding, and trouble eating.
Side effects from radiation therapy can include mild skin problems, nausea, vomiting, diarrhea, or fatigue. These usually go away a few weeks after treatment is finished. Radiation therapy may make the side effects of chemotherapy worse. Talk with your doctor about these side effects since there are ways to relieve them.
Stomach Cancer Survival Rates
The 5-year relative survival rate is the percentage of patients who are alive at least 5 years after the cancer is found. Those who die of other causes are not counted. Of course, patients might live more than 5 years after diagnosis. These 5-year survival rates are based on people with stomach cancer first treated more than 5 years ago. People treated today may have a more favorable outlook.
The overall 5-year survival rate of people with stomach cancer in the United States is about 23% . One reason for this is that most stomach cancers are found at an advanced stage. The outlook for survival is better if the cancer is in the lower part of the stomach than if it is in the upper part.
While numbers provide an overall picture, keep in mind that every person’s situation is unique and statistics can’t predict exactly what will happen in your case. Talk with your cancer care team if you have questions about your personal chances of a cure, or how long you might survive your cancer. They know your situation best.
