5.MAR.2018 3 MIN READ | 3 MIN READ

Stomach cancer is still the 4th most common cancer worldwide, despite a rapid decline in recent decades. But what causes it? Dr Melvin Look has the answers.

Dr Melvin Look, general surgeon at Mount Elizabeth Hospital, explains what you need to know about gastric cancer and stomach infections.

What is stomach cancer? 

Stomach cancer, also known as gastric cancer, occurs when the cells lining the walls of the stomach become cancerous. A mass, or ulcer, may form within the stomach, causing initial symptoms like heartburn, stomach pain, nausea and loss of appetite. 

The highest rates of gastric cancer are found in Asia, Eastern Europe and South America. In Singapore, it is the 7th most common cancer in males and the 9th most common cancer in females. And in certain subgroups, the risk is much higher. The lifetime risk for gastric cancer in Chinese men, for example, is about 1 in 50. 

Despite advancements in surgery and medical knowledge, most patients in Singapore are still diagnosed with stomach cancer at a late stage, which makes it difficult to treat. Unfortunately, unlike countries like Japan and Korea, Singapore doesn’t have any established screening programmes to detect new cases at an early stage.

What are the symptoms of stomach cancer?

Symptoms of stomach cancer
The earliest symptoms of stomach cancer include:

  • Indigestion
  • Heartburn
  • Feeling bloated
  • Nausea 
  • Loss of appetite

However, these symptoms can be caused by several different conditions, so it’s important to speak to your doctor for a proper diagnosis. 

Later symptoms may include:

  • Stomach pain or swelling
  • Blood in your stool
  • Vomiting
  • Weight loss
  • Trouble swallowing 
  • Tiredness

What causes stomach cancer?

Your stomach has 5 parts:

  • Cardia: The top part, closest to your food pipe
  • Fundus: The upper part, where undigested food is stored
  • Body (corpus): The main part, where your food is partially digested
  • Antrum: The lower part, where the food mixes with gastric juice
  • Pylorus: The bottom part, which acts as a valve to the small intestine

Cancers that originate from the cardia are usually associated with obesity and gastroesophageal reflux (GERD), while those in the antrum and pylorus are usually linked to the helicobacter pylori infection, smoking, a high intake of salty and smoked foods, and a family history of stomach cancer. 

Other things that may increase your risk include:

  • Type A blood
  • Epstein-Barr Virus (EBV)
  • Working in coal, metal, timber or rubber industries
  • Exposure to asbestos

What’s an helicobacter pylori (H. pylori) infection?

H. pylori infection
H. pylori is a type of bacteria that lives in the stomach. In some cases, it can cause inflamed ulcers to the grow in the lining of the stomach and intestines. This makes it more likely for mutated cells to develop and become cancerous. 

No one really knows where the bacteria originally came from or how it was first introduced to humans, but poor hygiene and contaminated food are likely factors in its spread. Almost 60% of adults carry the bacteria, but most of them won’t even know it. 

If you do have symptoms, they can include:

  • Ache or burning stomach pain
  • Nausea
  • Loss of appetite
  • Feeling bloated
  • Excessive burping

A course of antibiotics can rid your body of the infection. 

What’s the Epstein-Barr Virus (EBV)?

EBV is the virus that causes mononucleosis, or ‘mono’. It causes flu-like symptoms, including fever, fatigue, rash, sore throat, swollen glands and weak muscles. But again, like H. pylori, you can have it and not even know it. And the virus can stay in your body and become active again, even months or years later.

Unfortunately, there is no specific treatment for mono. The best way to avoid catching it is to stay away from people who have mono symptoms. 

While the link between EBV and stomach cancer is relatively new, about 9% of stomach cancers are thought to be associated with it.  

Will treating an H. pylori infection reduce my risk of cancer?

Reducing risk of cancer
Overall population studies do suggest that reducing the number of H. pylori infections can help to reduce the number of cancer cases. In one such study, the incidence of stomach cancer actually decreased by 25%. Therefore, early diagnosis of H. pylori could help to reduce your risk of developing cancer in the future.

If you have any of the symptoms of an H. pylori infection, consult your doctor. They can perform a non-invasive test to rule out other possible causes. A gastroscopy (a small camera inserted down your oesophagus) can also check for any signs or symptoms of stomach cancer at the same time.

 

References

Alempijevic, A., Milosavljevic, T. & Sokic-Milutinovic, A. (2015, November 7). Role of Helicobacter pylori Infection in Gastric Carcinogenesis: Current Knowledge and Future Directions. World Journal of Gastroenterology 21(41): 11654-11672.

Chen, T.H., Chiu, H.M. & Lee, Y.C., et al. (2013). The Benefit of Mass Eradication of Helicobacter pylori Infection: a Community-Based Study of Gastric Cancer Prevention. Gut 62: 676-682.

Dan, Y.Y., So, J.B. & Yeoh, K.G. (2006). Endoscopic Screening for Gastric Cancer. Clinical Gastroenterology and Hepatology 4: 709-716.

Fock, K.M, Katelaris, P. & Sugano, K., et al. (2009). Second Asia-Pacific Consensus Guidelines for Helicobacter pylori Infection. Journal of Gastroenterology and Hepatology 24: 1587-1600.

González, C.A., Liso, J.M. & Pardo, M.L., et al. (2010). Gastric Cancer Occurrence in Preneoplastic Lesions: a Long-Term Follow-Up in a High-Risk Area in Spain. International Journal of Cancer 127(11):2654-2660.

Okamoto, S., Uemura, N. & Yamamoto, S., et al. (2001). Helicobacter pylori Infection and the Development of Gastric Cancer. New England Journal of Medicine 345(11):784-789.

Singapore Cancer Registry. Interim Annual Report. Trends in Cancer Incidence in Singapore 2010-2014.

5.MAR.2018
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Look Chee Meng Melvin
General Surgeon
Mount Elizabeth Hospital

Dr Melvin Look is a general surgeon practising at Parkway East Hospital. He underwent further training at the National Cancer Center Hospital in Tokyo on a Ministry of Health Fellowship in Upper Gastrointestinal Cancer Surgery and also spent a year working in the Royal Infirmary of Edinburgh, United Kingdom, as an honorary consultant in upper gastrointestinal surgery. Other training awards he received include a TTSH Scholarship in Advanced Laparoscopic Surgery at the Mount Sinai Medical Centre, New York, and an International Cancer Fellowship from the Union Internationale Contre le Cancer for the Treatment of Peritoneal Cancer at the Washington Cancer Institute in Washington DC.