What is stomach cancer?

Stomach cancer occurs when abnormal cells grow uncontrollably in the stomach. The stomach is part of the digestive system, where food is churned and broken down mechanically, aided by stomach acid. The abnormal cells that grow to form a cancer can spread to other parts of the body (metastasize).

Stomach and the digestive system. 


The cause of stomach cancer, as with other cancers, is due to damage to cellular DNA. This damage results in uncontrolled cell growth, which leads to a cancer. Cancers invade nearby tissue, or cells can break off and spread throughout the body (metastasize) via the bloodstream or lymphatic system. The exact causes of this cellular damage to cells in the stomach are not known.


The genetic material of all living cells and some viruses. The full name is deoxyribonucleic acid.

Lymphatic system

A network of vessels, lymph nodes, the spleen and other organs that transport lymph fluid between tissues and bloodstream.

Risk factors

Risk factors for stomach cancer include:

  • Age - most cases of stomach cancer occur in people over 50 years of age;
  • Smoking - smoking doubles the risk of developing stomach cancer;
  • Gender - stomach cancer affects twice as many men as women;
  • Genetics and family history - inheriting genes that increase the risk of cancers of the digestive system, such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (HPNCC);
  • Helicobacter pylori infection - this is the bacteria that can cause stomach ulcers, but it is also associated with an increased risk of developing stomach cancer, and;
  • Partial gastrectomy for ulcer disease - people are more likely to develop stomach cancer decades after having this procedure.


A unit of inheritance (heredity) of a living organism. A segment of genetic material, typically DNA, that specifies the structure of a protein or related molecules. Genes are passed on to offspring so that traits are inherited, making you who you are and what you look like.


An open sore in the skin or mucous membranes such as those of the stomach lining, intestine or mouth.

Familial adenomatous polyposis

An inherited condition, caused by a faulty gene, which leads to multiple polyps in the bowel that invariably develop into bowel cancer by a young age.



This is by far the most common type of stomach cancer. It originates in the glandular cells of the stomach.

Squamous cell cancer

This is a rare type of stomach cancer that originates in squamous cells. These are flat cells located between the glandular cells in the lining of the stomach.

Glandular cells

Specialized cells that secrete materials such as lubricants and hormones.


Treatment outcomes can vary greatly depending on the stage of cancer. It is staged according to the size and location of the cancer, and whether it has spread to nearby or distant lymph nodes, or organs throughout the body.

Stage 0

The cancer has not spread beyond the lining the stomach.

Stage I

The cancer has spread to the first layer of the stomach, but not the muscles.

Stage II

The cancer has spread to the muscle layer of the stomach or the lymph nodes near it.

Stage III

The cancer has spread to the lymph nodes near the stomach and the muscle lining, but not the organs.

Stage IV

The cancer has spread throughout the body to distant organs.

Signs and symptoms

Early stomach cancer may not have any symptoms. Symptoms of stomach cancer can include:

  • Indigestion (heartburn, bloating);
  • Fatigue, nausea and vomiting;
  • Pain or difficulty swallowing;
  • Blood in the vomit or feces;
  • Feeling full after not eating much, and;
  • Loss of appetite and weight loss.

Methods for diagnosis

Your doctor will ask you questions about your medical history and any symptoms you have and feel your abdomen for any abnormalities. If your doctor thinks you might have stomach cancer, they'll refer you to a specialist in diseases of the gastrointestinal tract (gastroenterologist or upper gastrointestinal surgeon).

If stomach cancer is suspected, the following tests can be performed:

Laboratory tests

Complete blood count

Your doctor might order a complete blood count to check for signs of anemia caused by bleeding in the gastrointestinal tract.

Fecal occult blood test

Your doctor might order a fecal occult blood test to look for blood in the stool.


Endoscopic ultrasound

Sound waves are used to create an image of the stomach and nearby structures. During an endoscopic ultrasound, you are sedated and an ultrasound probe is attached to an endoscope and inserted via the throat into the stomach.

Computerized tomography (CT) scan

A computerized tomography scan uses X-rays to develop a 3D image of the body. This can detect small tumors effectively.

Magnetic resonance imaging (MRI)

Magnetic resonance imaging is like a CT scan, but uses magnetism instead of X-rays.

Positron emission tomography (PET)

Positron emission tomography can provide images of the cancer and any sites of cancer spread.


Upper endoscopy

During an upper endoscopy, you will be sedated and a long, narrow telescopic camera will be inserted into your throat to view the upper digestive system. Any suspicious lesions can be biopsied (see below).

Endoscopy.An endoscopy procedure. 


Laparoscopy is a procedure that allows your doctor to see the organs in the abdomen and pelvis. It involves making a small incision in your abdominal wall and inserting a thin device with a camera called a laparoscope. Gas is pumped into the cavity to expand it and give your doctor a clear view. Laparoscopy can be used simply to inspect the pelvic and abdominal areas, but also in conjunction with more complicated surgery, such as removing tissue samples or burning away scar tissue. These more complicated procedures require additional incisions in the abdomen for other instruments to be used. This procedure is often performed after cancer has already been found to check that it hasn't spread, as scans can miss some of the smaller tumors.

Tissue biopsy

Analysis of a biopsy is the only way to determine whether any abnormal cells are cancerous. Biopsies are often taken during an endoscopy, but if a scan indicates a tumor that is located deep in the stomach wall, a biopsy can be then taken using a fine needle guided by ultrasound. The biopsies are sent away for microscopic examination by the pathologist.


The part of the body that lies between the chest and the pelvis.


A deficiency in red blood cells or hemoglobin in the body.


This test involves inserting a thin, flexible, lit tube (endoscope) into the intestines, via the rectum or the throat.

Gastrointestinal tract

The membrane-lined series of organs extending from the mouth to the anus through which food passes during digestion.

Types of treatment


Surgery involves the removal of part or all of the stomach and any cancerous lymph nodes.

Adjuvant therapy

Adjuvant therapy is given after surgery, with the aim of preventing the cancer from returning. It can take the form of radiotherapy, and/or chemotherapy.

Neoadjuvant therapy

Like adjuvant therapy, neoadjuvant therapy also uses one or more of radiotherapy or chemotherapy, but is provided before surgery.


Chemotherapy works by attacking cancer cells and stopping their reproduction. Various medications are used, which can be administered intravenously or orally. They are often given in cycles, followed by rest periods, which help to reduce the toxic side effects of chemotherapy. Your doctor will monitor your dosage and treatment schedule to ensure optimal therapeutic dosage is administered, with minimum side effects.


In this type of therapy, focused X-rays are applied to the area where the tumor is located. Another form of radiation therapy is brachytherapy. This involves implanting radioactive seeds in the tumor or the nearby area, which deliver cell-destroying radiation directly into the tumor. Radiotherapy can be used alone, or in addition to surgery and/or chemotherapy.

Other therapies

Some people diagnosed with cancer seek out complementary and alternative therapies. None of these alternative therapies are known to cure cancer, but some can help people feel better when used together with conventional medical treatment. It is important to discuss any treatments with your doctor before starting them.

Potential complications

Treatment side effects

There are a range of side effects of treatment for stomach cancer, including the following:

  • Dietary problems - surgery can result in loss of appetite, weight loss and vomiting bile. It can also cause dumping syndrome, in which you feel dizzy and faint about 30 minutes after eating. It can also cause problems in calcium absorption and anemia from problems with iron absorption;
  • Radiation enteritis - this is when the intestine becomes inflamed as a result of radiotherapy;
  • Nausea, vomiting and fatigue as a result of chemotherapy and radiotherapy;
  • Altered bowel habits - constipation or diarrhea;
  • Joint and muscle pain can occur after a treatment session and can last a few days;
  • Temporary hair loss from the head and body due to some types of chemotherapy. It will grow back after treatment has ended, and;
  • Tingling in the hands and feet - some chemotherapeutic agents can affect the nerves. It is important to tell your doctor if you develop these symptoms.

Advanced stomach cancer

This is when the cancer spreads to other parts of the body through the bloodstream and lymphatic system. The growth of the cancer in other body parts results in a destructive effect on their function.


A deficiency in red blood cells or hemoglobin in the body.

Lymphatic system

A network of vessels, lymph nodes, the spleen and other organs that transport lymph fluid between tissues and bloodstream.


Survival rates tell you what portion of people with the same type and stage of cancer are still alive a certain length of time (usually 5 years) after they were diagnosed. These numbers can't tell you how long you will live, but they might help give you a better understanding about how likely it is that your treatment will be successful.

It is important to remember survival rates are only an indication, and are based upon the averages of previously treated patients. It is not an absolute prognosis for an individual. It is often difficult to accurately predict an individual's cure or survival rate. Constant advances in treatment are continually improving these statistics.


You may reduce your risk of getting stomach cancer by quitting smoking, maintaining a healthy diet that is high in fresh fruit and vegetables and fiber. You may benefit from receiving treatment for confirmed Helicobacter pylori infection, if necessary. If you have genetic conditions that put you at a greater risk of developing stomach cancer, your doctor may recommend regular screening, where possible.

FAQ Frequently asked questions