Stomach cancer, or gastric cancer, is a malignancy that develops in the lining of the stomach. The stomach is an organ in the upper abdomen that stores and digests food.
The stomach has four tissue layers: the mucosa, submucosa, muscle layer and outer layer. The mucosa is the inner-most layer that produces digestive juices (specifically hydrochloric acid and pepsin) to break down food, and mucus to protect the lining of the stomach. The second inner-most layer, the submucosa, supports the mucosa layer, and provides blood and nutrients to the stomach. It contains a variety of blood vessels, lymphatic vessels, and nerves. The next layer is the muscle layer, also known as the muscularis externa, which is responsible for producing contractions to further help break down food and push it to the small intestine. The outer-most layer is the serosa, which is a smooth, protective membrane that surrounds the stomach.
Stomach cancers are more common in males, and are generally found in people over 60 years old. However, anyone can develop this disease.
Types of Stomach Cancer
There are several types of stomach cancers, which can be categorised by the type of cells they develop from.
Gastric Adenocarcinomas
Gastric adenocarcinomas are the most common form of stomach cancer. Adenocarcinomas are cancers arising from mucus-producing glands in organs, and start in the mucosa of the stomach. Gastric adenocarcinomas can be aggressive, but can have a good prognosis when caught early.
Linitis Plastica
Linitis plastica, also known as gastric scirrhous carcinoma, is a very rare form of stomach cancer that is classified as a form of gastric adenocarcinoma. It develops in the lining of the stomach and spreads to the muscles of the stomach wall, making it thick, hard and rubbery. Once this occurs, the stomach can't hold as much food, and doesn't move as much as it should during digestion. Linitis plastica is often aggressive, and may not have as good of a prognosis as other stomach cancers.
Gastric Lymphomas
Gastric lymphomas are stomach cancers that often develop from lymphocytes in the lining of the stomach. It is a type of non-Hodgkin lymphoma (cancer of the lymphatic system) that affects the immune system. They are often slow-growing, and may carry a good prognosis.
Gastrointestinal Stromal Tumours (GISTs)
A gastrointestinal stromal tumour (GIST) is a rare type of sarcoma (cancer arising from bones or soft tissues) that forms in lining of the gastrointestinal tract. More specifically, they develop in interstitial cells of Cajal (ICC), which play a critical role in the intestinal contractions required for digestion. For more information on GISTs, please refer to the Rare Cancers Australia Gastrointestinal Stromal Tumours (GIST) page.
Rare forms of Stomach Cancer
These forms of stomach cancer are very rare:
Treatment
If stomach cancer is detected, it will be staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.
Cancers can be staged using the TNM staging system:
- T (tumour) indicates the size and depth of the tumour.
- N (nodes) indicates whether the cancer has spread to nearby lymph nodes.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for stomach cancer may include:
- Surgery, potentially including:
- Subtotal or partial gastrectomy (partial removal of the stomach).
- Total gastrectomy (complete removal of the stomach).
- Lymphadenectomy (removal of affected lymph nodes).
- Surgery to insert a feeding tube (often required after surgery on the stomach).
- Chemotherapy.
- Radiation therapy.
- Targeted therapy.
- Immunotherapy.
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia treatment options page.
Risk factors
While the cause of stomach cancer remains unknown, some of the following factors may increase the risk of you developing the disease:
- Being over 60 years old.
- Having had a previous infection of Helicobacter pylori (H. pylori).
- Having had a previous partial gastrectomy.
- Having a history of smoking tobacco.
- Low red blood cell levels.
- Having a family history of stomach cancer.
- Having certain genetic conditions, such as:
- Chronic inflammation of the stomach (also known as chronic gastritis).
- Being overweight or obese.
- Excessive alcohol consumption.
- Having a diet with high salt content.
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Early symptoms
Symptoms of a stomach cancer may include:
- Unexplained weight loss and/or loss of appetite.
- Difficulties swallowing.
- Indigestion, which may carry its own set of symptoms:
- Abdominal pain/burning.
- Heartburn.
- Frequent burping.
- Reflux.
- Nausea and/or vomiting.
- Abdominal pain.
- Feeling full after eating small quantities of food.
- Abdominal swelling and/or bloating.
- Fatigue.
- Anaemia.
- Vomit with blood in it.
- Discoloured stools.
Not everyone with the symptoms above will have cancer, but see your general practitioner GP if you are concerned.
Diagnosis/diagnosing
If your doctor suspects you have a stomach cancer, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment.
Physical examination
Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities.
Imaging & blood tests
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), barium x-ray and/or positron emission tomography (PET scan), depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.
Endoscopy & biopsy
An endoscopy is a surgical procedure that involves inserting a long, flexible tube with a light and small camera through oesophagus and into the stomach. You will be given a sedative or anaesthetic throughout the procedure. You will be asked to fast for several hours prior to the procedure. An endoscopy is often done as a day surgery. Your doctor will discuss the risks and any possible complications prior to the procedure.
Throughout the procedure, your doctor may also perform an endoscopic ultrasound to guide the needle during a biopsy, or to check for signs of cancer metastasis. If any abnormalities are observed, your doctor will remove a small tissue sample for analysis.
Prognosis (Certain factors affect the prognosis and treatment options)
While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on the rate and depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. Generally, early-stage stomach cancers have a better prognosis and survival rates. However, if the cancer is advanced and has spread, the prognosis may not be as good and there may be a higher risk of cancer recurrence. It is very important to discuss your individual circumstances with your doctor to better understand your prognosis.
References
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.