Stomach cancer is a common disease found worldwide but its incidence in Australia is comparatively low. Most of patients are above 55 years of age at time of diagnosis. If diagnosed early, there a good chance of cure. Advanced disease is less likely to be cured, however, treatment can still slow down the progression of the cancer.
What is the stomach?
The stomach is a part of gastrointestinal tract and is located in the upper abdomen below the ribs. The food that we eat is passed through the oesophagus (gullet) to the stomach.
The food which reaches the stomach is mixed up with the acid and chemicals produced by the stomach. Then this processed food reaches the duodenum (the first part of small intestine) where it is mixed more with the enzymes produced by the pancreas and the lining of the gut. The digested food is absorbed through the lining of the small intestine.
What is cancer?
Our body is made up of millions of tiny cells. There are many different cells in our body performing different action. Cancer is a disease of cell in which the affected cells function abnormally and start multiplying at an uncontrolled pace. As there are many types of cells, there are different kinds of cancer depending on the cell being affected.
A malignant tumour is a growth made up of millions of cancer cells. Malignant tumours damage nearby organs by invading them they also can spread to other parts of the body causing secondary tumours (metastases).
There are different types of cancer, some cancers are serious and some can be treated easily if diagnosed at an early stage. The outlook (prognosis) depends on the type and size of cancer and whether it has spread.
What is stomach cancer?
Cancer of stomach is one of the most common cancers worldwide (especially Japan and China) but it is less common in Australia. It is found more in males and tend to occur mostly in people over the age of 55.
Adenocarcinoma of the stomach
This is the most common type of stomach cancer. It arises from the cells lining the stomach. As cells multiply, the tumour invade through the wall of the stomach and affect near by organs such as the pancreas or liver. Cancer cells may spread up into the oesophagus or down into the duodenum. Cancer cells may spread via the lymph channels to the lymph nodes or via the blood into the liver or other distant organs.
Gastric (stomach) lymphoma
This is cancer of the lymphatic tissue present within the wall of the stomach.
GIST (Gastrointestinal Stromal Tumour)
This is a tumour arising from the muscle layer of the stomach wall. Click here to read more about Gastrointestinal Stromal Tumour - GIST.
Carcinoid tumour of the stomach
This is a slow growing cancer of the hormones producing cells present in the lining of the stomach.
What causes stomach cancer?
Caner arise from one abnormal cell. The reason of why a cell starts to multiply out of control is still not fully understood but a damage to the genes is the likely cause. Most people develop stomach cancer without an obvious cause but there are certain risk factors that predispose to stomach cancer:
1. Increasing age
2. Pernicious anaemia. This is a type of anaemia caused by lack of vitamin B12.
3. Certain foods such as a salty, pickled and smoked food.
5. Helicobacter pylori (H pylori) infection. This is a bug that infects the lining of the stomach.
6. Previous stomach resection e.g. surgery for stomach ulcers in the past.
7. Family history. Rarely stomach cancer runs in families.
8. Blood group type A
What are the symptoms of stomach cancer?
Early cancer does not cause symptoms. As the cancer grow it may cause:
1. Discomfort in the upper abdomen after eating
2. Indigestion, loss of appetite and feeling sick and full after eating
3. Weight loss
4. Symptoms of anaemia from gradual loss of blood
5. Vomiting of blood or passage of blood in stool often causing the stool to become black.
6. Feeling tired easily
7. Difficulty with swallowing due to block of the stomach.
8. Various symptoms due to spread of cancer to other parts of the body.
How is stomach cancer diagnosed?
Gastroscopy (upper GI endoscopy): A gastroscope is a flexible telescope passed through the mouth under sedation. It examines the oesophagus, stomach and the duodenum. In addition to being able to see, the gastroscope has a channel that admits a small forceps to take a small amount of tissue (biopsy). The biopsy is examined under microscope to determine if there is cancer. A biopsy is essential to confirm the diagnosis of cancer.
What are the tests to determine the extent and spread (i.e. stage) of stomach cancer?
Once the diagnosis of stomach cancer is made other test are done to determine the extent and spread of the cancer (stage). This is called staging of the cancer. The common tests include:
1. CT scan
2. MRI scan
3. Ultrasound scan
4. Endoscopic ultrasound
5. Staging laparoscopy
The purpose of staging is to determine:
1. Depth of cancer penetration through the stomach wall.
2. Spread to lymph nodes.
3. Spread to distant organs of the body (metastases).
4. Spread on the inside of the abdominal cavity.
The extent and spread of cancer (stage) determines the best treatment methods and gives a reasonable indication of the future outlook (prognosis).
What are the treatment options for stomach cancer?
There are three options for treatment: surgery, chemotherapy, and /or radiotherapy.
The best treatment depends on the stage of cancer and the general health of patient. After a thorough assessment of the condition and a full discussion with the patient three different aims of treatment emerge:
1. To cure the cancer. Stomach cancer in early stages can be cured in some patients. Surgery with or without chemotherapy is essential if the aim is cure.
2. To control the cancer: If cure is not realistic, it is often possible to slow the progress with chemotherapy with or without radiotherapy.
3. To ease symptoms: If cure is not possible, symptoms can be eased with different methods such as painkillers, food supplements and anti nausea medications.
Surgery for stomach cancer:
Early cancer can be cured with surgery. Surgery involve removing the most of the stomach (subtotal gastrectomy) or all of the stomach (total gastrectomy). The lymph nodes related to the stomach are also removed and these are examined for spread to determine if chemotherapy is needed too.
Advanced cancer that is not possible to cure can still benefit from surgery to ease symptoms. Removal of the cancer or bypass of the stomach may be used to bypass blockage by cancer.
Occasionally surgery can be done laparoscopically (key-hole surgery).
Chemotherapy for stomach cancer:
Anti-cancer medicine kill cancer cells. Chemotherapy can be used together with surgery to cure the cancer (called adjuvant chemotherapy) or used to ease symptoms only (called palliative chemotherapy).
Radiotherapy for stomach cancer:
Radiotherapy uses high energy x-rays to kill cancer cells. It is sometimes used to reduce the size of cancer which is causing symptoms or stop the bleeding from a cancer that is not suitable for surgery.
What is the outlook (prognosis) of stomach cancer?
Early cancer limited to the stomach can be cured with surgery. Unfortunately, most cases in Australia are not diagnosed at an early stage.
If cancer has spread through the wall of the stomach or to other parts of the body, a cure is less likely. Still, treatment with chemotherapy can reduce the progression of the cancer.