Stomach Cancer

What is stomach cancer?

The stomach is part of the digestive system and functions to contain, break down and digest the food we eat. It is a hollow, muscular organ shaped like a large pouch, located in the upper abdomen, under the ribs. The upper part of the stomach connects to the oesophagus and the lower part leads to the small intestine.

Stomach cancer or gastric cancer can affect any part of the stomach. The cancer can form an ulcer or a mass within the stomach which can spread throughout the entire wall of the stomach.

How common is stomach cancer?

Stomach cancer is the 8th most common cancer in males in Singapore and the 10th most common cancer among females in Singapore. It more commonly occurs in men and individuals aged between 50 and 70 years old.

What are the types of stomach cancer?

There are different types of stomach cancer, classified by the type of cell where the cancer begins. The most common type which accounts for 90-95% of stomach cancers is adenocarcinoma, which starts in the glandular cells of the stomach lining.

Other types of stomach cancer include gastrointestinal stromal tumours (GIST), which form in the interstitial cells of Cajal, gastric lymphoma, which is a cancer of the immune system tissue found in the stomach wall and neuroendocrine tumours or carcinoid tumours, which start in the hormone-producing cells of the stomach.

What are the symptoms of stomach cancer? 

There are often no or mild symptoms in the early stages of stomach cancer. When the cancer progresses, some symptoms may show.

Symptoms of stomach cancer may include:

• Persistent indigestion (reflux) or a burning sensation after meals (heartburn)
• Upper abdominal discomfort or pain after a meal
• Feeling bloated after eating
• Feeling very full after a small meal
• Loss of appetite
• Unexplained and unintentional weight loss
• Nausea or vomiting
• Blood in the stools or black stools

When should you see a doctor?

Make an appointment with your doctor if you have any signs or symptoms that worry you.

How is stomach cancer prevented? 

There are several ways to lower the risk of stomach cancer:

• Reduce the consumption of salted and preserved foods
• Adopt a diet with high intake of fruits and vegetables. Vitamin A and C, in particular, appear to lower the risk of stomach cancer.
• Avoid smoking and inhaling second-hand smoke
• Exercise regularly and maintain a healthy weight

What are the risk factors of stomach cancer?

While the exact cause of stomach cancer is unknown, several factors have been found to play a role in its development. These risk factors include:

• A chronic infection by a bacteria called helicobacter pylori
• Gastroesophageal reflux disease
  
• A diet high in salted or preserved (cured/smoked/pickled) foods
• A diet low in fruits and vegetables
• Smoking and alcohol
• Family history of stomach cancer
• Hereditary syndromes such as familial adenomatous polyposis (FAP), Li-Fraumeni syndrome, hereditary nonpolyposis colorectal cancer (HNPCC) and Peutz-Jeghers syndrome
• Medical conditions that may contribute to stomach cancer such as:
  • Anaemia (megaloblastic anaemia and pernicious anaemia)
  • Previous stomach operation with partial removal of the stomach (gastrectomy)
  • A stomach disorder called atrophic gastritis, which results in lower than normal production of digestive juices
  • Stomach polyps

These risk factors are more commonly seen in people who have stomach cancer. Having one or more of these risk factors does not mean that you will develop stomach cancer. Stomach cancer may still develop in patients with none of the above risk factors.

How is stomach cancer diagnosed?

Tests and procedures used to diagnose stomach cancer include:

• Upper endoscopy or gastroscopy
  

  During the procedure, an endoscope (a thin fibre-optic tube containing a small camera) is passed through the mouth and down the throat to check for abnormal areas in the oesophagus, stomach and duodenum.

• Biopsy
  

  If any suspicious areas are discovered during the endoscopy, a tissue sample may be taken and sent to the lab for testing and analysis.

• Barium meal X-ray
  

  The patient will be given a liquid containing barium to swallow. This outlines the stomach wall to help locate any tumours or abnormal areas. X-rays of the oesophagus and stomach will then be taken.

• Faecal occult blood test
  

  A lab test performed to determine the presence or absence of hidden (occult) blood in the stool.

If stomach cancer is diagnosed, further tests may be required to determine if the cancer has spread and to determine the stage of the cancer. Some of the tests include:

• Computerised Tomography (CT) Scan
  

  A CT scan is a type of scan where x-ray beams are rotated around the body to produce a series of x-ray images photographed from different angles. A CT scan is able to show the stomach clearly to confirm the location of the cancer. This test can also be used to look for cancer that has spread to the lymph nodes, liver or abdomen.

• Positron Emission Tomography (PET) Scan

  Positron Emission Tomography (PET) scan uses radiation to produce 3-D images of the body. Due to the unique characteristics of stomach cancer, PET scan may not be able to detect certain types of stomach cancer.
  

• Exploratory surgery
  

  Exploratory surgery may be recommended to look for signs that the cancer has spread beyond the stomach. This is usually performed laparoscopically (via key-hole surgery), where several small incisions are made and a special camera is inserted into the abdominal cavity to check for the spread of the cancer.

How is stomach cancer treated? 

There are a few effective treatment options for stomach cancer. In general, treatment for stomach cancer depends on the following factors:

• Size, location and extent of the tumour
• Stage of the disease when the cancer is found
• Patient’s general state of health

The main treatment for stomach cancer is surgery. However chemotherapy and radiotherapy may also be required for some patients. Endoscopic resection may be possible for very early cancers confined to the mucosa. In advanced stage disease, chemotherapy is generally used in combination with surgery, and radiotherapy may also be administered.

New treatment approaches such as immunotherapy, have been shown in clinical trials to be effective for certain types of stomach cancer.

An individual with cancer should be assessed by a specialist to determine which treatment is best suited for them.

Surgery

Surgery for stomach cancer is known as gastrectomy. There are two types of gastrectomy:

• Partial or subtotal gastrectomy is the removal of a part of the stomach. After a partial gastrectomy, the surgeon will connect the remaining portion of the stomach to the oesophagus or the small intestine, depending on which part of the stomach was removed.
• Total gastrectomy is the removal of the entire stomach, suspicious lymph nodes near the stomach and other surrounding tissue. After a total gastrectomy, the surgeon will connect the oesophagus directly to the small intestine.

Chemotherapy

Chemotherapy is sometimes recommended after surgery if there is a risk that the cancer might return. It may also be used before surgery to shrink the cancer, so that it is more likely to be removed completely during surgery.

In patients with advanced stomach cancer, chemotherapy may be used alone or with targeted drug therapy.

Radiotherapy

Radiotherapy uses powerful energy beams to kill cancer cells. It can also be used before surgery to shrink the cancer so that it is more easily removed during surgery. In some instances, the doctor may recommend radiotherapy to reduce the risk of a cancer recurrence after surgery.

Targeted therapy

Targeted drug treatments work by blocking specific weaknesses present within cancer cells, causing the cancer cells to die. Targeted drug therapy is usually combined with chemotherapy for treating advanced or recurrent stomach cancer.

Immunotherapy

Immunotherapy is a drug treatment that helps a patient’s immune system fight cancer. Immunotherapy may be recommended if the stomach cancer is advanced, recurs or spreads to other parts of the body.

How can you prepare for stomach cancer surgery? 

Your surgeon will perform a comprehensive medical work-up including blood tests and scans to see if you are suitable for surgery and advise you on the risks involved.

Before surgery, the anaesthesia team will also assess your fitness for surgery and advise you on various aspects of general anaesthesia and pain control after surgery.

What can you expect after stomach cancer surgery?

Post-surgery, you will be put on an intravenous infusion (drip through a vein) to replace your body’s fluids until you are ready for fluids, followed by soft, then solid foods. You may experience rumbling noises, nausea, cramps, diarrhoea or dizziness 10 to 30 minutes after eating. This is known as “dumping syndrome” and usually disappears in 3 to 12 months.

After recovering from surgery, you will be given regular outpatient appointments to see your team of doctors. During these appointments, you may have blood tests and scans to check if the cancer recurs.

It is important to follow your doctor's advice, keep to your clinic visits and do the recommended scans, so that timely treatment can be administered if the cancer or other problems occur.

Is stomach cancer curable if caught early?

There are many factors that influence the prognosis of patients with stomach cancer, such as the location, type and stage of the cancer, as well as the patient's age and overall health. Stomach cancer is usually most treatable when it is found early, before the cancer has spread to other parts of the body.

Is stomach cancer an aggressive cancer?

Yes, stomach cancer can be aggressive, especially in its advanced stages. However, the outlook can vary depending on the stage at which it is diagnosed and other factors.

How long can stomach cancer go undetected?

Stomach cancer can be difficult to detect in its early stages because it often produces no symptoms. As the cancer progresses, the symptoms that appear such as persistent indigestion or upper abdominal discomfort or bloating can be mistaken for normal gastrointestinal issues. Stomach cancer can go undetected for some time before the symptoms become concerning enough for the patient to go for diagnostic testing.