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What Is Stomach Cancer?

Stomach (gastric) cancer is cancer that starts in the cells lining the stomach. The stomach is an organ on the left side of the upper abdomen that digests food. The stomach is part of the digestive tract, a series of hollow, muscular organs joined in a long, twisting tube from the mouth to the anus. The digestive tract processes nutrients in foods that are eaten and helps pass waste material out of the body:

  • Food moves from the throat to the stomach through a tube called the esophagus.
  • After food enters the stomach, it is broken down by stomach muscles that mix the food and liquid with digestive juices.
  • After leaving the stomach, partly digested food passes into the small intestine and then into the large intestine.
  • The end of the large intestine, called the rectum, stores the waste from the digested food until it is pushed out of the anus during a bowel movement.

Types of stomach cancer

Adenocarcinoma of the stomach begins in the mucus-producing cells in the innermost lining of the stomach. Nearly all stomach cancers are adenocarcinomas.

Adenocarcinoma of the stomach is divided into two main classes, depending on where it forms in the stomach:

  • Gastric cardia cancer begins in the top inch of the stomach, just below where it meets the esophagus.
  • Non-cardia gastric cancer is cancer that begins in all other sections of the stomach.

Adenocarcinoma of the stomach also may be described as intestinal or diffuse, depending on how the cells look under a microscope:

 

  • Intestinal adenocarcinomas are well differentiated, meaning the cancer cells look similar to normal cells under a microscope.
  • Diffuse adenocarcinomas are undifferentiated or poorly differentiated, meaning the cancer cells look different from normal cells under a microscope. Diffuse adenocarcinomas tend to grow and spread more quickly than the intestinal type and be harder to treat.

Gastroesophageal junction adenocarcinoma (GEJ) is a cancer that forms in the area where the esophagus meets the gastric cardia. GEJ may be treated similarly to stomach cancer or esophageal cancer.

Gastrointestinal neuroendocrine tumors are cancers that begin in neuroendocrine cells (a type of cell that is like a nerve cell and a hormone-making cell) that line the gastrointestinal tract. Neuroendocrine cells make hormones that help control digestive juices and the muscles used in moving food through the stomach and intestines.  Learn about gastrointestinal neuroendocrine tumors.

Gastrointestinal stromal tumors (GIST) begin in nerve cells that are found in the wall of the stomach and other digestive organs. GIST is a type of soft tissue sarcoma.  Learn about gastrointestinal stromal tumors. 

Primary gastric lymphoma is a type of non-Hodgkin lymphoma that forms in the stomach. Most primary gastric lymphomas are either mucosa-associated lymphoid tissue (MALT) gastric lymphoma or diffuse large B-cell lymphoma of the stomach.  

Rarely, other types of cancer, such as squamous cell carcinoma, small cell carcinoma, and leiomyosarcoma, can also begin in the stomach. 

Stomach Cancer Causes and Risk Factors

Stomach cancer is caused by certain changes to the way stomach cells function, especially how they grow and divide into new cells. There are many risk factors for stomach cancer, but many do not directly cause cancer. Instead, they increase the chance of DNA damage in cells that may lead to stomach cancer. To learn more about how cancer develops, see What Is Cancer?.  

A risk factor is anything that increases the chance of getting a disease. Some risk factors for stomach cancer, like tobacco use, can be changed. However, risk factors also include things people cannot change, like their age and family history. Learning about risk factors for stomach cancer is important because it can help you make choices that might prevent or lower your risk of getting it.  

Who gets stomach cancer

Stomach cancer is the fifth most common cancer worldwide. It is more common in countries in East Asia, Eastern Europe, and South and Central America than in the United States and other Western countries.

Anyone can get stomach cancer. In the United States, the disease occurs more often among Black, Hispanic, Asian/Pacific Islander, and American Indian/Alaska Native individuals than among White individuals. Males are nearly twice as likely as females to be diagnosed with stomach cancer, and Black males are nearly twice as likely as White males to die of it. In recent years, stomach cancer rates have been increasing in younger females, particularly among Hispanic females. Stomach cancer can be diagnosed at any age, but the risk increases as a person gets older.

Stomach Cancer Causes and Risk Factors

Stomach cancer is caused by certain changes to the way stomach cells function, especially how they grow and divide into new cells. There are many risk factors for stomach cancer, but many do not directly cause cancer. Instead, they increase the chance of DNA damage in cells that may lead to stomach cancer. To learn more about how cancer develops, see What Is Cancer?.  

A risk factor is anything that increases the chance of getting a disease. Some risk factors for stomach cancer, like tobacco use, can be changed. However, risk factors also include things people cannot change, like their age and family history. Learning about risk factors for stomach cancer is important because it can help you make choices that might prevent or lower your risk of getting it.  

There are several risk factors for stomach cancer. Different risk factors may increase the risk of cancer in different parts of the stomach. For example, Helicobacter pylori (H. pylori) infection increases the risk of cancer in the lower and middle part of the stomach, while obesity and gastroesophageal reflux disease (GERD) increase the risk of cancer in the upper stomach.

Other medical conditions

The risk of stomach cancer is increased in people who have 

  • chronic atrophic gastritis (thinning of the stomach lining caused by long-term inflammation of the stomach) 
  • atrophic gastritis with intestinal metaplasia (a condition in which the cells that line the stomach are replaced by cells that normally line the intestines) 
  • Epstein-Barr virus infection
  • pernicious anemia (an autoimmune condition in which the intestines can’t properly absorb vitamin B12, resulting in a low red blood cell count)
  • obesity (excess body weight) 
  • gastroesophageal reflux disease (a condition in which stomach acid repeatedly flows back into the esophagus)

Stomach Cancer Symptoms

Early on, stomach cancer usually doesn’t have symptoms, making it hard to detect. Symptoms usually begin after the cancer has spread.   

When symptoms of early-stage stomach cancer do occur, they may include  

  • indigestion and stomach discomfort
  • a bloated feeling after eating
  • mild nausea
  • loss of appetite
  • heartburn

Symptoms of advanced stomach cancer (cancer has spread beyond the stomach to other parts of the body) may include the symptoms of early-stage stomach cancer and

  • blood in the stool  
  • vomiting  
  • weight loss for no known reason  
  • stomach pain  
  • jaundice (yellowing of eyes and skin)  
  • ascites (build-up of fluid in the abdomen)  
  • trouble swallowing  

These symptoms may be caused by many conditions other than stomach cancer. It’s important to check with your doctor if you have any of these symptoms. Your doctor will ask when your symptoms started and how often you’ve been having them. If it is stomach cancer, ignoring symptoms can delay treatment and make it less effective.  

Stomach Cancer Treatment

Different types of treatments are available for stomach cancer. You and your cancer care team will work together to decide your treatment plan, which may include more than one type of treatment. Many factors will be considered, such as the stage of the cancer, your overall health, and your preferences. Your plan will include information about your cancer, the goals of treatment, your treatment options and the possible side effects, and the expected length of treatment.    

Endoscopic mucosal resection

Endoscopic mucosal resection is a procedure that uses an endoscope to remove carcinoma in situ and early-stage cancer from the lining of the digestive tract. An endoscope is a thin, tube-like instrument with a light and a lens and tools to remove tissue.

Stomach Cancer Treatment

Surgery

Surgery is a common treatment for stomach cancer. The type of surgery depends on where the cancer is located.   

Other treatments may be given in addition to surgery:  

  • Treatment given before surgery is called preoperative therapy or neoadjuvant therapy. Chemotherapy may be given before surgery to shrink the tumor and reduce the amount of tissue that needs to be removed during surgery. Chemoradiation given before surgery, to shrink the tumor, is being studied.  
  • Treatment given after surgery, to lower the risk that the cancer will come back, is called adjuvant therapy. After the doctor removes all the cancer that can be seen, some patients may be given chemotherapy, radiation therapy, or both to kill any cancer cells that are left.    

Gastrectomy

Gastrectomy, the removal of part or all of the stomach, is the main surgery for stomach cancer:  

  • Subtotal gastrectomy is the removal of the part of the stomach that contains cancer, nearby lymph nodes, and parts of other tissues and organs near the tumor. The spleen may also be removed. 
  • Total gastrectomy is the removal of the entire stomach, nearby lymph nodes, and parts of the esophagus, small intestine, and other tissues near the tumor. The spleen may also be removed. Then the surgeon attaches the esophagus to the small intestine so the patient can continue to eat and swallow.

Endoluminal stent placement

Endoluminal stent placement may be done when the tumor blocks the passage into or out of the stomach. In this procedure, the surgeon places a stent (a thin, expandable tube) from the esophagus to the stomach or from the stomach to the small intestine to allow the patient to eat normally.

Endoluminal laser therapy

Endoluminal laser therapy is a procedure in which an endoscope (a thin, lighted tube) with a laser attached is used as a knife to open a gastrointestinal blockage.

Gastrojejunostomy

Gastrojejunostomy is the removal of the part of the stomach with cancer that is blocking the opening into the small intestine. Then the surgeon connects the stomach to the jejunum (a part of the small intestine) to allow food and medicine to pass from the stomach into the small intestine.

Radiation therapy

Radiation therapy uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. Stomach cancer is sometimes treated with external radiation therapy. This type of radiation therapy uses a machine outside the body to send radiation toward the area of the body with cancer.

Chemotherapy

Chemotherapy (also called chemo) uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. 

Chemotherapy for stomach cancer is usually systemic, meaning it is injected into a vein or given by mouth. When given this way, the drugs enter the bloodstream to reach cancer cells throughout the body.  

Targeted therapy

Targeted therapy uses drugs or other substances to identify and attack specific cancer cells. Your doctor may suggest biomarker tests to help predict your response to certain targeted therapy drugs.

Immunotherapy

Immunotherapy helps a person’s immune system fight cancer. Your doctor may suggest biomarker tests to help predict your response to certain immunotherapy drugs. Learn more about Biomarker Testing for Cancer.   

Immunotherapy drugs used to treat stomach cancer include  

  • nivolumab
  • pembrolizumab

These drugs work in more than one way to kill cancer cells. They are also considered targeted therapy because they target specific changes or substances in cancer cells.    

Hyperthermic intraperitoneal chemotherapy (HIPEC)

Regional chemotherapy is a method of placing chemotherapy directly into an organ or a body cavity, such as the abdomen, to mainly affect cancer cells in those areas.   

A type of regional chemotherapy called hyperthermic intraperitoneal chemotherapy, or hot chemotherapy, is being studied to treat stomach cancer and may be offered at certain treatment centers. After the surgeon has removed as much of the cancer as possible during surgery, a chemotherapy drug, such as mitomycin or cisplatin, is warmed and pumped directly into the peritoneal cavity through a thin tube for about 2 hours. The surgeon then drains the chemotherapy from the abdomen and rinses the abdomen before closing the incision.   

Follow-up testing

Some tests that were done to diagnose or stage the cancer may be repeated to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests. These tests are sometimes called follow-up tests or check-ups.

You may also have blood tests for tumor markers such as CEA and CA 19-9. Increased levels of these markers may mean your stomach cancer has come back.