Stomach Cancer – Causes, Signs and symptoms

Stomach Cancer

Also called: Gastric Cancer

Reviewed By:
Mark Oren, M.D., FACP

Summary

Stomach cancer, also called gastric cancer, is a malignant cell growth that begins in the cells of the stomach and invades the surrounding healthy cells.  Stomach cancer is less common in the United States than in some other countries. In the past, it was one of the leading causes of cancer deaths in the U.S. However, the incidence of the disease has declined due to possible improvements with food handling and storage and better treatment of infections.

The stomach is a sac-like digestive organ located in the abdomen that is composed of five layers.  The innermost layer, called the mucosa, is the most common site for the start of stomach cancer.  From the mucosa, it can spread into the outer layers of the stomach lining and beyond to other tissues and organs.

Adenocarcinoma takes up 90 to 95 percent of stomach cancer cases, according to the American Cancer Society (ACS). This cancer develops from the glandular cells of the innermost lining (mucosa).  Other less common stomach cancers can develop in lymph tissue (lymphoma), hormone-producing cells (carcinoid tumors) or certain nerve cells(gastrointestinal stromal tumors or GIST).

The causes of stomach cancer are unknown but diet and certain bacteria infections have been strongly linked to the disease. In addition, smoking and obesity are considered risk factors for stomach cancer. Age plays a role in stomach cancer susceptibility with two-thirds of the cases occurring in individuals 65 years of age and older. Lifestyle and dietary changes can significantly impact a person’s risk of developing this cancer.

The signs and symptoms of stomach cancer rarely appear in the early stages of the disease. For this reason, stomach cancer often goes undetected until the later stages. The signs and symptoms of the disease can include abdominal pain, indigestion, bloating and unexplained weight loss. As the disease progresses, patients may develop jaundice and exhibit blood in their stools.

Diagnosis typically involves compiling the patient’s medical history, physical examination, blood tests, stool tests (e.g., fecal occult blood test) and imaging tests such as CAT scan and MRI. Biopsies of the suspected tissue are taken to identify cell type and rate of growth.

Treatment for stomach cancer often involves surgery, usually a partial or a total gastrectomy (removal of stomach tissue), as well as chemotherapy and radiation therapy. In many patients, treatment will use a combination of these therapies.

The overall 5-year survival rate for individuals with stomach cancer in the United States is about 23 percent, according to the ACS. The relatively low survival rate is due to the difficulty in detecting the cancer in its early stages. If stomach cancer is found and treated early, the 5-year survival rate increases to nearly 60 percent. In addition, cancers located in the lower portion of the stomach tend to have a better survival rate than those in the upper section. Early detection significantly improves the prognosis (outlook) for individuals diagnosed with this disease.

About stomach cancer

Stomach cancer, also called gastric cancer, is the malignant growth of cells in the stomach that can eventually invade the surrounding healthy cells. Stomach cancer often begins in the innermost lining of the stomach and metastasizes (spreads) outside of the stomach to the surrounding lymph nodes and organs. In more advanced stages, the cancer cells can spread to organs such as the lungs, liver, pancreas, colon, bones and ovaries in women.

The stomach is a sac-like organ located in the abdomen beneath the diaphragm and above the intestines that collects food and liquids after they travel through the esophagus. It is within the stomach that gastric juices mix with the food as part of the digestive process. The stomach is made of five layers.  The five layers of the stomach are:

  • Mucosa. Innermost layer where cancer typically first appears. Stomach acid and gastric enzymes are produced by the glands in this layer.
  • Submucosa. This layer supports the mucosa.
  • Muscularis. This layer is comprised of muscles that move the stomach during the digestive process.
  • Subserosa. The outer “wrapping” layer.
  • Outermost serosa. The outermost layer that protects the inner layers.

Stomach cancer usually begins in the innermost layer (mucosa) and then enters into the outer layers as the malignant cells grow and spread. While there are four main types of stomach cancer, adenocarcinoma is by far the most common, making up 90 to 95 percent of stomach cancer cases according to the American Cancer Society (ACS).

The ACS predicts that about 22,280 Americans will be diagnosed with stomach cancer in 2006. It occurs twice as often in men as in women and two-thirds of cases are found in people 65 years of age and older. The disease was once more common in the United States and was a leading cause of cancer deaths. Improved handling and storage of foods is thought to have contributed to its decline in the United States. Some physicians also believe the increased use of antibiotics to treat infections in children may be related to the lower incidence of the disease.

However, stomach cancer remains more common in some other countries in the world. The higher incidence may be related to less hygienic conditions and poorer refrigeration, which can lead to bacterial infections linked to the disease. In addition, many of these countries each large amounts of foods that are preserved by pickling or smoking – factors that are associated with stomach cancer.

In 2006, the ACS estimates that 11,430 people in the United States will die from stomach cancer. The overall 5-year survival rate for Americans with stomach cancer is 23 percent. If the cancer is detected in the early stages, the 5-year survival rate increases to 60 percent. The prognosis also depends on the location of the cancer. Individuals with cancer in the upper portion of the stomach may have a poorer chance of survival than those with the disease in the distal or lower portion of the stomach.

Stomach cancer is difficult to detect in the early stages because there may be few or no symptoms. For this reason, the overall survival rate for this cancer has not significantly improved during the past 15 years. As with most cancers, prognosis for survival improves with early detection and treatment

Types and differences of stomach cancer

More than 90 percent of stomach cancers are adenocarcinomas that originate in the glandular cells in the mucosa of the stomach’s inner lining, according to the American Cancer Society (ACS). Types of adenocarcinoma of the stomach include:

  • Type 1. This cancer forms in the cells of the stomach closest to the duodenum (beginning of the small intestine). This cancer is associated with infection with H. pylori bacteria and a diet high in certain foods, such as smoked meats.
  • Type 2. This less common type is linked to genetic factors. All the cells of the stomach can be affected. This type is also much more aggressive than type 1, and can quickly grow and spread to the lymph nodes, pancreas, liver and colon.

Rare types of stomach cancers include:

  • Lymphomas. Cancer that affects the immune system cells along the stomach wall. According to the ACS, lymphomas account for 4 percent of stomach cancers. The growth rate of lymphomas varies. Mucosa-associated lymphoid tissue (MALT) lymphomas are often associated with H. pylori infection and may be curable if discovered in the early stages.
  • Carcinoid tumors. Tumors that originate in the stomach’s hormone-producing cells. These tumors are rare and grow and spread slowly to other tissues in the body. According to the ACS, these tumors represent about 3 percent of stomach cancers.
  • Gastrointestinal stromal tumors (GISTs). Rapid-growing tumors that spread quickly to other areas and do not respond well to standard treatment. These rare tumor cells originate from interstitial cells of Cajal, which are part of the autonomic nervous system. GISTs can be found throughout the gastrointestinal tract, but are most common in the stomach.

Risk factors and causes of stomach cancer

The causes of stomach cancer are unknown. However, certain forms of Helicobacter pylori or H. pylori bacteria are strongly associated with this cancer. In fact, it is believed that the large proportion of stomach cancer cases in developing countries are due to this bacteria and a reduced access to antibiotics. Recent studies have suggested, however, that the bacteria may be a greater risk factor for cancer of the lower stomach versus types of upper stomach cancer. The studies may explain why there has been a decline in lower stomach cancer in Western countries that utilize more antibiotics for intestinal conditions.

Foods preserved by drying, smoking, salting or pickling also are strongly associated with the disease. Countries where the diets are heavy in these types of foods have a high incidence of stomach cancer.

In the United States, where stomach cancers are rare, a person’s risk is determined by the presence of one or more risk factors. These factors may increase the likelihood that a person will develop stomach cancer but do not indicate that a person will definitely develop the disease. Some people may not have any risk factors and still develop stomach cancer. Some risk factors are out of a person’s control, and others involve elements that can be altered.

Uncontrollable or inherited risk factors for stomach cancer include:

  • Age. The majority of the cases develop in individuals aged 65 and older.

  • Gender. Men have about twice the risk of this disease than women.

  • Race and ethnicity. Stomach cancer is most common in Asians and Pacific Islanders. African Americans and Hispanics are at higher risk than whites. The cause of this increase is believed to lie primarily in the traditional diets of these groups.

  • Family history of close relative with stomach cancer.

  • Type A blood. Including both positive and negative, type A blood contains antigens (immune system substances) in the red blood cells that may contribute to higher risk. The reason why people with type A blood are more likely to get stomach cancer is unknown.

  • Familial adenomatous polyposis (FAP) or other cancer syndromes.

Medical or infectious conditions that are risk factors include:

  • Helicobacter pylori (H. pylori) bacteria. This bacterial infection of the stomach is strongly associated with stomach cancer, particularly in the lower stomach. Long-term infection with this type of bacteria may lead to inflammation of the stomach lining resulting in pre-cancerous changes.
  • Chronic gastritis (stomach inflammation)

  • Gastric polyps

  • Previous stomach surgery

  • Epstein-Barr virus (virus that causes infectious mononucleosis)

  • Menetrier’s disease (rare disease that alters the lining of the stomach)

  • Pernicious anemia.  This disease causes the stomach to atrophy (become thinner than normal) and produce an inadequate amount of protein, which results in a shortage of red blood cells.

Dietary risk factors include:

  • Nitrates and nitrites used as preservatives in food

  • Salty, smoked or pickled foods or red meats. Research has indicated that eating red meat more than 13 times per week doubles the risk of stomach cancer. The risk increases if the meet is barbecued and cooked well done.

  • Poor refrigeration of foods

  • Obesity

Other lifestyle risk factors include:

  • Smoking

  • Abuse of alcohol

  • Environmental exposure to toxins such as coal products, asbestos, rubber and nickel

  • Low socioeconomic levels

  • Geographic locations where diets of high-salt and pickled foods are common such as Asian, Eastern European and Latin American countries

  • Areas and populations with reduced access to antibiotics to treat medical conditions

Signs and symptoms of stomach cancer

The first sign of stomach cancer may be microscopic internal bleeding that can be detected only by testing for blood in the stool. Signs and symptoms of stomach cancer rarely appear in the early stages, but can include:

  • Indigestion and stomach discomfort
  • Mild nausea
  • Loss of appetite
  • Bloating after eating
  • Heartburn
  • Weakness and fatigue

Symptoms in advanced stages:

  • Blood in stools
  • Black, tarry stools
  • Mild anemia
  • Vomiting blood or after meals
  • Weight loss
  • Persistent and chronic stomach pain
  • Jaundice (yellowing of the skin and the whites of the eyes)
  • Ascites (buildup of fluid in the abdomen)
  • Difficulty swallowing(dysphagia)

Patients exhibiting these symptoms should consult a physician. The above symptoms may indicate any number of less serious conditions, such as peptic ulcer. A physician will prescribe diagnostic tests to determine the cause of the symptoms.

Diagnosis methods for stomach cancer

Physicians will use a variety of diagnostic methods to determine if cancer is present in an individual. Initially, the patient’s medical history will be compiled for possible contributing factors. A thorough physical examination will be completed with particular focus on the abdomen and lymph nodes.

A number of tests may be administered to help identify the location of tumors and diagnose or rule out cancer. If cancer is detected, these tests can determine the type of cancer as well as the stage (spread) of the cancer. Tests and evaluations used to detect stomach cancer can include:

  • Blood tests (e.g., complete blood counts). These tests are taken to determine chemical or hormonal imbalances that may indicate cancer cells in the tissues or organs, or anemia that indicates bleeding from the tumore.

  • Fecal occult blood test (FOBT). A sample of stool (solid waste) is examined chemically for the presence of trace amounts of blood. Simple home FOBT can be conducted by the patient as well. There is a significant incidence of false positives and negatives with FOBT.

  • X-ray. The use of x-rays to create images of the body. X-rays and scans can help to detect if there is metastasis (cancer spread) to the bones or other organs.

  • Barium x-ray. A series of x-rays of the esophagus and stomach are taken after the patient drinks a liquid containing barium, a chalky compound that coats the GI tract and makes it visible on x-ray scans.

  • Computed axial tomography (CAT scan). Cross-sectional images are taken of the body using specialized x-rays and a computer analysis. Contrast medium (dye) may be used to help locate tumors and abnormalities in the body.
  • Magnetic resonance imaging (MRI). Radio wave technology is used to create detailed images of internal organs and tissues in the body.
  • Positron emission tomography (PET) scan. A minimally radioactive sugar is injected into the bloodstream and is rapidly absorbed by the cancer cells, making them detectable by forming hot spots on an image. PET scan can be used to determine the spread of cancer.
  • Bone scan. Radioactive material injected into the bloodstream collects in the bones, and images are taken by scanner. The images detect cancer cells in the bones.

  • Upper endoscopy. A thin lighted tube called an endoscope is guided down the throat and used to check for abnormalities in the esophagus, stomach and duodenum.  The procedure is usually performed with the patient sedated.
  • Endoscopic ultrasound (EUS). An endoscope is used with an ultrasound device. This device is passed through the nose or throat into the stomach, where sound waves are sent to the stomach and images of stomach tumors are produced. This ultrasound is effective in detecting small tumors that may not appear on other imaging tests.
  • Laparoscopy. A thin, lighted instrument is attached to a tiny television camera and inserted into the abdomen through a small incision. Laparoscopy can detect tumors and any metastasis to the surrounding tissue as well.

  • Biopsy. Samples from suspected tissue can be taken during laparoscopy, endoscopy, needle biopsy or surgery. A pathologist views the cells under a microscope to determine the presence of cancer.

  • Genetic testing. DNA is analyzed for genetic alterations that can indicate a predisposition for cancer as well as potential prognosis for survival.

Treatment options for stomach cancer

Factors influencing the patient’s treatment plan include the type and stage of the cancer, the patient’s general health and other contributing factors.  For most patients, a cancer care team will be established to diagnose and plan all aspects of the patient’s treatment. The team is typically headed up by a medical oncologist and may also include:  

  • Radiation oncologist
  • Surgeon
  • Pathologist
  • Gastroenterologist
  • Dietician

The treatment of stomach cancer will depend on a variety of factors. In most cases, patients may receive a combination of the following treatments:

  • Surgery. Surgical removal of cancerous tissue. Surgery is considered the only way to possibly cure stomach cancer.  Curative surgery is performed for stages 0, I, II, and III. These tumors are resectable, meaning they can be surgically removed.  In the later stages, stomach cancer surgery is palliative, meaning it is done to relieve the patient of symptoms, not necessarily cure the cancer. The following types of surgery may be used:

    • Endoscopic mucosal resection. Surgical removal of a tumor or portion of an organ through an endoscope. This procedure is performed in the early stages of cancer and when there is little risk of the cancer spreading to the lymph nodes or surrounding tissues.
    • Subtotal or partial gastrectomy. Removal of the cancerous part of the stomach and in some cases, the first section of the small intestine. This type of surgery is can allow the patient to eat with less difficulty than when the entire stomach is removed.
    • Total gastrectomy. The entire stomach is removed because the cancer is in the middle and upper parts of the stomach. The nearby lymph nodes, parts of the esophagus, small intestine and any other cancerous tissue near the tumor also may be removed. After total gastrectomy, individuals can only eat very small amounts of food at a sitting as they will fill up quickly.
    In the event that the stomach is blocked but the tumor cannot be removed through the above surgeries, the following procedures may be performed:

    • Endoluminal stent placement. A stent (a thin, flexible tube) is inserted to keep a passage open that may have been blocked by a tumor, such as the opening connecting the esophagus to the stomach or a major blood vessel in the stomach.

    • Endoscopic laser surgery. An endoscope with a laser attached is inserted into the body and the tumor is cut out with the laser beam.

    • Electrocautery. An electrical current is sent to create heat that removes lesions or controls bleeding.

  • Chemotherapy. The use of powerful drugs to control the growth of cancer cells by killing them or preventing cell division. This method can be used in addition to surgery to prevent a return of cancer cells or before surgery to make a tumor smaller. In addition, chemotherapy may be used as primary treatment for cancer that has spread to distant organs.
  • Radiation therapy. Use of high energy x-rays to destroy or shrink cancer cells  External beam radiation is the type of radiation typically used for stomach cancer. Research indicates that radiation therapy, particularly when combined with chemotherapy, can be effective in preventing stomach cancer from retuning after surgery.
  • Biological therapy (also called immunotherapy).  This treatment is used to stimulate the immune system to fight the cancerous cells or, in some cases, directly attack the cancer.

  • Clinical trials. A physician may recommend participation in a clinical trial that will test new experimental treatments. Experimental therapies may include new chemotherapy drugs or a variety of combined treatments.

  • Comfort (palliative) care. Patients have the option of receiving treatment for their symptoms without treating the cancer. Stage IV stomach cancer is generally treated with palliative chemotherapy and/or radiation therapy and other treatments because metastasis is extensive. Surgery is palliative at this stage, to stop bleeding, prevent blockages or shrink a tumor.

Prevention methods for stomach cancer

Although the exact causes of stomach cancer are unknown, certain risk factors are strongly correlated. The following lifestyle changes can reduce the likelihood of developing stomach cancer:

  • Quit smoking. Smoking is a major risk factor for stomach cancer. Patients should ask their physician about smoking cessation programs and other methods to quit smoking.

  • Limit alcohol. Too much alcohol consumption can cause chemical changes that may affect cancer cell growth.

  • Improve diet. Patients should consume increased amounts of fresh fruits and vegetables as well as dietary fiber. Individuals should also reduce the consumption of red meats, especially those that are highly processed. Nitrates used for processing meats can contribute to the occurrence of stomach cancer. In addition, individuals should limit their intake of salty, smoked and pickled foods.

  • Maintain healthy weight. Obesity is considered a risk factor for this disease. Maintaining a good weight also contributes to overall health.

  • Avoid occupational and environmental toxins.  Exposure to coal dust, asbestos and nickel may increase the risk of stomach cancer.

Individuals should consult a physician if they have digestive symptoms such as nausea, vomiting, bloating, diarrhea, constipation or abdominal pain. While these may be caused may a number of less serious conditions, they may indicate ulcers caused by infection with H. pylori bacteria. Symptoms of ulcers should be addressed as they can be associated with stomach cancer.

Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, may lower the risk of stomach cancer as well as colorectal cancer, according to the American Cancer Society. However, these drugs can cause internal bleeding, interact dangerously with other drugs and result in other problems. They should not be taken regularly without a physician’s recommendation.

Ongoing research

Scientists are studying many possible new ways to diagnose, treat and prevent stomach cancer, including:

  • Chemopreventionwith antibiotics and antioxidants to find ways to prevent stomach cancer. Ongoing studies are evaluating the role of vitamin C in preventing the disease.
  • Using drugs that boost the immune system to fight cancer cells. Some studies are using interleukins to increas a patient’s immune system while other trials are evaluating vaccines. In passive immunotherapy, scientists are using man-made antibodies to seek and destroy specific cancer cells while avoiding healthy cells in the body.
  • Advanced types of surgery to remove stomach cancer.
  • Delivery of chemotherapy drugs directly through the peritoneum (lining of the abdominal cavity) for a more direct affect. In addition, clinical trials are testing new chemotherapy drugs and combinations.
  • Using sentinel lymph node mapping to identify metastasis (cancer spread).
  • Combination treatments, such as surgery and radiation therapy or chemotherapy, to increase survival rates. Studies are focusing on the benefits of adding radiation therapy and/or chemotherapy before and after surgery in certain patients.

Staging stomach cancer

Stomach cancer is staged by tumor size, level of spread to the lymph nodes and spread to other organs. The staging system is used by physicians to gauge the extent of growth and spread of the cancer cells. The patient’s age, the extent of the spread of the cancer and the condition of the patient’s general health aids in determining the treatment path with the best possible outcomes.

The American Joint Committee on Cancer (AJCC) has developed a more detailed “TNM” staging system used by physicians:

  • “T” describes the extent of tumor growth.
  • “N” describes the extent of lymph node involvement.
  • “M” describes the extent of distant metastasis.

The stages of stomach cancer are quite detailed and will be determined by analysis by a pathologist. A general description of the stages of stomach cancer is as follows:

  • Stage 0. Cancer is located in the inside lining of the stomach only. This is also called carcinoma in situ.

  • Stage I. Cancer may have spread through the innermost and middle layers of the stomach wall. Surrounding lymph nodes may or may not be affected.

  • Stage II. Cancer is located in the innermost, middle and/or outermost layers of the stomach. Unless the outermost layer is involved, cancer is also in several nearby lymph nodes.

  • Stage III. Cancer is located in the middle and/or outermost layers of the stomach and more lymph nodes per layer than in stage II. If any nearby organs are affected, the lymph nodes and distant organs are not.

  • Stage IV. Cancer may be located in nearby organs, lymph nodes and/or it has spread to distant organs.

  • Recurrent. Cancer that recurs after treatment and may return to the stomach or other parts of the body such as liver or lymph nodes.

The following 5-year survival rates for stomach cancer, according to the American Cancer Society:

Stage5-Year Survival Rate
077 percent
I57 to 66 percent
II35 percent
III12 to 17 percent
IV3 percent

Questions for your doctor on stomach cancer

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctors the following questions about stomach cancer:

  1. Do I have any of the risk factors associated with stomach cancer?
  2. What tests will be used to determine if I have stomach cancer?
  3. What type of cancer do I have?
  4. What is the stage of my cancer?
  5. Am I a candidate for surgery? If so, which procedure?
  6. If I have a total gastrectomy, how will it affect my diet and eating?
  7. Will I be able to maintain adequate nutrition following my surgery?
  8. What are my other treatment options?
  9. What are the risks associated with the treatments?
  10. What is the prognosis with my type and stage of cancer?
  11. Can I make any lifestyle changes to reduce my risk of stomach cancer?
  12. What are the odds of other family members developing stomach cancer if I have the disease?
  13. Are there any genetic tests that can help predict the risk of stomach cancer?
  14. Can you refer me to a support group for my cancer?
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