Stomach cancer (also called gastric cancer) starts in the stomach. There are a few types, but almost all cases are adenocarcinomas of the stomach, tumors that develop from the cells that form the mucosa, the innermost lining of the stomach.
Most people use the word “stomach” to refer to the body below the chest and above the pelvis. The medical word for this area, though, is “abdomen.” What you might call a stomachache, doctors call abdominal pain because the stomach is only one of many organs in the abdomen, including the small intestine, large intestine or colon, and pancreas.
Stomach cancer should not be confused with other cancers that can occur in the abdomen—these cancers have different symptoms, different outlooks, and different cancer treatments.
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.
The stomach has five parts:
- Cardia. The part closest to the esophagus, where chewed food comes from the mouth through the chest.
- Fundus. The upper part of the stomach next to the cardia.
- Body or corpus. The main part of the stomach, between the upper and lower parts.
- Antrum. The lower portion near the small intestine, where food mixes 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 stomach wall has five layers, which are important in determining the stage of stomach cancer, plus treatment and prognosis:
- Mucosa. The innermost layer, where stomach acid and digestive enzymes are made. Most stomach cancers start in this layer.
- Submucosa. A supporting layer.
- Muscularis propria. A thick layer of muscle that moves and mixes the stomach contents.
- Subserosa. One of two outer layers that wrap the stomach.
- Outermost serosa. The other outer layer.
Stomach cancer occurs when cells in these layers—most often the mucosa—begin growing out of control. This happens because of genetic mutations in these cells. We still don’t know the exact cause of stomach cancer, but research has identified several risk factors, including a stomach infection from the H. pylori bacteria.
As a cancer grows from the mucosa into deeper layers, the stage becomes more advanced. Stomach cancers typically develop slowly over many years. Before a true cancer develops, pre-cancerous changes often occur in the mucosa—these early changes rarely cause symptoms and often go undetected.
Types of stomach cancer
Adenocarcinomas. About 90% to 95% cancers of the stomach are adenocarcinomas. These cancers develop from the mucosa, the mucus-producing cells that line the stomach.
Lymphomas. These are cancers of the immune system tissue that are sometimes found in the wall of the stomach. Stomach cancer treatment and outlook depend on the type of lymphoma.
Gastrointestinal stromal tumor (GIST). These rare tumors 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. Although GISTs can be found anywhere in the digestive tract, most are found in the stomach.
Carcinoid tumor. These tumors start in hormone-making cells of the stomach. Most of these tumors do not spread to other organs.
Stomach cancer symptoms
See your provider if you experience any of these signs and symptoms:
- Fatigue and stomach pain
- Feeling bloated after eating, or feeling full after eating small amounts
- Severe, persistent heartburn or indigestion
- Unexplained, persistent nausea and/or vomiting
- Unintentional weight loss
Risk factors of Stomach cancer
Factors that increase your risk of stomach cancer include:
- A diet high in salty and smoked foods, and low in fruits and vegetables
- Family history of stomach cancer
- H. pylori infection
- Long-term stomach inflammation
- Pernicious anemia
- Stomach polyps
Questions and answers (FAQs)
Your cancer multidisciplinary team will include a nutritionist, who will set up your new diet as part of your treatment plan. Your diet will depend on the type of surgery you had. For the most part, you diet will be similar to what it was before surgery, but you will have to make some changes in what you eat and how you eat. Many patients find it’s best to eat in small quantities throughout the day, especially after a total gastrectomy.
Often stomach cancer does not present with any symptoms in the early stages. In addition, initial symptoms are often confused with other stomach conditions.
H. pylori. About half the population in the U.S. has some sort of H. pylori infection, but the vast majority will not develop stomach cancer from it.
Stomach cancer treatment and recovery
Your gastrointestinal oncology team will work with you to create the best treatment plan for your situation.
Your treatment plan may include any or all of these treatments:
Surgery for resectable cancer
The main treatment for stomach cancer. Your surgeon will know the right procedure for your case:
- Endoscopic resection. Endoscopic mucosal resection and endoscopic submucosal resection can be used only to treat some very early-stage cancers, where the chance of spread to the lymph nodes is very low. The surgeon passes an endoscope down the throat and into the stomach. Surgical tools can be passed through the endoscope to remove the tumor and part of the normal stomach wall around it.
- Subtotal (partial) gastrectomy. Often recommended if the cancer is only in the lower part of the stomach. Only part of the stomach is removed, sometimes along with part of the esophagus or the first part of the small intestine. The remaining section of stomach is then reattached. Some lymph nodes are also removed.
- Total gastrectomy. Done if the cancer has spread throughout the stomach. It is also often advised if the cancer is in the upper part of the stomach, near the esophagus. The surgeon removes the entire stomach, nearby lymph nodes, and omentum, and may remove the spleen and parts of the esophagus, intestines, pancreas, or other nearby organs. The end of the esophagus is then attached to part of the small intestine.
Palliative surgery for unresectable cancer
For people with unresectable stomach cancer, palliative surgery can often still be used to help control the cancer or to help prevent or relieve symptoms or complications.
- Subtotal gastrectomy. Removing the part of the stomach with the tumor can help treat problems such as bleeding, pain, or blockage in the stomach, even if it does not cure the cancer.
- Gastric bypass (gastrojejunostomy). Tumors in the lower part of the stomach may eventually grow large enough to block food from leaving the stomach. To bypass the lower part of the stomach, the surgeon attaches part of the small intestine (the jejunum) to the upper part of the stomach, allowing food to leave the stomach through the new connection.
- Endoscopic tumor ablation. An endoscope is used to guide a laser beam to vaporize parts of the tumor. This can be done to stop bleeding or help relieve a blockage without surgery.
- Stent placement. Another option to keep a tumor from blocking the opening at the beginning or end of the stomach is to use an endoscope to place a stent—a hollow metal tube—in the opening.
- Feeding tube placement. Some people with stomach cancer are not able to eat or drink enough to get adequate nutrition. We can place a feeding tube through the skin of the abdomen and into the distal part of the stomach or the small intestine and deliver liquid nutrition.
- Radiofrequency ablation. A special probe with tiny electrodes that kill cancer cells.
- Cryosurgery. An instrument that freezes and destroys abnormal tissue.
- Chemotherapy. Drugs that destroy cancer cells, usually by stopping the cancer cells’ ability to grow and divide. We often use more than one drug at a time for maximum results.
- Targeted therapy or novel therapy. Drugs that target the cancer’s specific genes, proteins, or the tissue environment that contributes to cancer growth and survival. In recent years, targeted therapy has proven to be increasingly successful at controlling myeloma and improving a prognosis.
- Immunotherapy or biologic therapy. Uses materials made either by the body or in a laboratory to improve, target, or restore immune system function.
- Other drug therapy. We may give steroids alone or at the same time as targeted therapy or chemotherapy.
- Radiation therapy. High-energy X-rays or other particles that destroy cancer cells.
Stomach cancer diagnosis
To properly diagnose stomach cancer, your provider will first take your medical history and perform a physical exam. This includes an assessment of symptoms, checking your overall health and feeling your abdomen for any abnormal changes. Then, if necessary, your doctor will refer you to a gastroenterologist, who specializes in diseases of the digestive tract.
Further diagnostic testing may include:
- Upper endoscopy or esophagogastroduodenoscopy (EGD). The main test used to find stomach cancer. Your gastroenterologist uses an endoscope—a flexible, lighted tube with a small video camera on the end—to see the lining of your esophagus, stomach, and first part of the small intestine. The endoscope can also take a biopsy sample.
- Endoscopic ultrasound (EUS). Uses sound waves to produce images of the stomach.
- Biopsy. The only way to tell for sure if it is definitively cancer is by doing a biopsy. Biopsies to check for stomach cancer are most often obtained during upper endoscopy, where your doctor takes a sample of the abnormal area and sends it to a lab for examination. The samples are checked to see if they contain cancer, and if they do, what type of stomach cancer.
- Imaging tests. X-rays, magnetic fields, sound waves, or radioactive substances to create pictures of the inside of your body.
- Computed tomography (CT or CAT) scan. Uses X-rays to make detailed, cross-sectional images of your body. Unlike a regular x-ray, a CT scan creates detailed images of the soft tissues in the body. CT scans can also be used to guide a biopsy needle into a suspected area of cancer spread, called a CT-guided needle biopsy.
- Magnetic resonance imaging (MRI) scan. Like CT scans, MRI scans show detailed images of soft tissues in the body.
- Positron emission tomography (PET) scan. A PET scan can look for possible areas of cancer spread in all areas of the body at once.
- PET/CT scan. We can do both a PET and CT scan at the same time.
Stomach cancer stages
Part of a diagnosis is determining the stage of stomach cancer, which helps direct the proper treatment. The stages of adenocarcinoma of the stomach or esophagus include:
- Stage I. At this stage, the tumor is limited to the top layer of tissue that lines the inside of the esophagus or stomach. Cancer cells also may have spread to a limited number of nearby lymph nodes.
- Stage II. The cancer at this stage has spread deeper, growing into a deeper muscle layer of the esophagus or stomach wall. Cancer may also have spread to more of the lymph nodes.
- Stage III. At this stage, the cancer may have grown through all the layers of the esophagus or stomach and spread to nearby structures. Or it may be a smaller cancer that has spread more extensively to the lymph nodes.
- Stage IV. This stage indicates that the cancer has spread to distant areas of the body.
Five-year stomach cancer survival rates
Number of Patients Diagnosed – UCHealth 282 – State of Colorado – 1,090
Number of Patients Surviving – UCHealth 98 – State of Colorado – 280
*n<30, 5 Year Survival – (Date of diagnosis 1/1/2010–12/31/2014)
National Cancer Institute (NCI). Stomach (Gastric) Cancer (https://www.cancer.gov/types/stomach)
MedlinePlus: National Library of Medicine. Stomach Cancer (https://medlineplus.gov/stomachcancer.html)
National Center for Biotechnology Information (NCBI): National Library of Medicine. of (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3406280/)