Bowel cancer, also known as colon, rectal or colorectal cancer, occurs when abnormal cells grow uncontrollably…
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 (metastasise).
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 (metastasise) via the bloodstream or lymphatic system. The exact causes of this cellular damage to cells in the stomach are not known.
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.
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.
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.
The cancer has not spread beyond the lining the stomach.
The cancer has spread to the first layer of the stomach, but not the muscles.
The cancer has spread to the muscle layer of the stomach or the lymph nodes near it.
The cancer has spread to the lymph nodes near the stomach and the muscle lining, but not the organs.
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 faeces;
- 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:
Complete blood count
Your doctor might order a complete blood count to check for signs of anaemia caused by bleeding in the gastrointestinal tract.
Faecal occult blood test
Your doctor might order a faecal occult blood test to look for blood in the stool.
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.
Computerised tomography (CT) scan
A computerised tomography scan uses X-rays to develop a 3D image of the body. This can detect small tumours 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.
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).
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 tumours.
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 tumour 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.
Types of treatment
Surgery involves the removal of part or all of the stomach and any cancerous lymph nodes.
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.
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 tumour is located. Another form of radiation therapy is brachytherapy. This involves implanting radioactive seeds in the tumour or the nearby area, which deliver cell-destroying radiation directly into the tumour. Radiotherapy can be used alone, or in addition to surgery and/or chemotherapy.
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.
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 anaemia 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 diarrhoea;
- 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.
Prognosis varies according to the type and stage of the cancer, but the overall five-year survival rate for stomach cancer, in Australia as of 2010, is 27%. For those who survive the first year, the survival rate almost doubles to 51%.
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 fibre. 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.