Does H. Pylori Cause Cancer?

H. pylori is one of the most common bacteria. According to NIH, With approximately 50% of the global population infected with H. pylori at least once, this small organism is not to be looked down upon. 

From abdominal pain to nausea and vomiting, H. pylori infection can cause a myriad of gastroenterological problems. While these symptoms are bad on their own, can they spiral into something more sinister… like cancer? 

 The short answer is yes: it can increase the risk of stomach cancer. However, such cases are rare, and highly preventable with timely and accurate treatment. Read on to find out more about H. pylori infection, how it can increase the risk of stomach cancer, and how to get a full recovery! 

H. Pylori Cause Cancer?


What is H. Pylori?

Helicobacter pylori (H. pylori) is a spiral-shaped bacteria that grows in the stomach lining (gastric mucosa) and upper part of the small intestines (duodenum).  

The stomach has an acidic environment to digest food and kill harmful bacteria. However, H. pylori can neutralise the stomach acid using an enzyme urease to convert urea to ammonia, which is alkaline. Hence, the bacteria can bypass the body’s defense mechanism and survive. In addition, the bacteria can attach itself to the stomach lining to hide from an immune attack. 

As the bacteria grow into the stomach tissues, the stomach lining degrades, causing inflammation (gastritis). Gastric acid can escape the stomach and injure the surrounding stomach cells, creating peptic ulcers. If left untreated, it can increase the risk of developing stomach (gastric) cancer.  

In Singapore, H. pylori has affected 31% of the population. Most cases are asymptomatic. However, if the infection has led to inflammation or stomach ulcers, patients may experience some symptoms including: 

  • Nausea 
  • Stomach pain 
  • Bloating 
  • Vomiting 
  • Burping 
  • Unexplained weight loss 
  • Loss of appetite  
  • Indigestion 


How is H. pylori infection transmitted and diagnosed?

H. pylori is passed from person to person through saliva such as kissing. Consuming food or drinks contaminated with the bacteria is another way of getting infected. The infection route continues as the bacteria resides in vomit or stool, which can be transmitted if one does not wash their hands after using the washroom. 

To determine if you have H. pylori infection, the doctor will perform one or more of these tests:  

  • Blood test: A small blood sample is extracted to test for antibodies against the bacteria.  
  • Stool test: You will need to provide a small stool sample, which will be tested for the presence of the bacteria.  
  • Breath test: The bacteria can convert urea to carbon dioxide and ammonia. Hence, a high carbon dioxide level is indicative of H. pylori infection. This can be tested by drinking a solution containing radioactive urea and collecting your breath via a collection bag. The presence of radioactive carbon dioxide in the bag is a positive result for H. pylori infection.  

If the results are ambiguous, the doctor may perform an endoscopy, which is a more invasive but conclusive approach that involves the insertion of an endoscope, a flexible tube with a camera allowing the doctor to inspect the gastrointestinal tract for signs of damage. This is typically accompanied by a biopsy, which is the extraction of a small tissue sample which will be tested for H. pylori.   

H. Pylori test


Does H. Pylori Cause Cancer?

Simply put, H. pylori can increase the risk of developing cancer.  

 If the infection is left untreated, the bacteria can grow and weaken the stomach lining. This allows the stomach acid to leave the stomach environment and damage the stomach cells, causing stomach ulcers. Overtime, this can lead to chronic gastritis, which is the inflammation of the stomach.  

 Constant inflammation could lead to constant cell death or repair, which makes cells highly susceptible to mutations, which are changes in the DNA sequences. This can trigger abnormal cell growth, leading to stomach (gastric) cancer.  

 In fact, H. pylori has been classified as a carcinogen (cancer-causing agent) by the International Agency for Research on Cancer. While rare, it leads to several types of stomach cancers 


Non-cardia gastric adenocarcinoma 

Non-cardia gastric adenocarcinoma is a type of cancer that begins in the glandular (mucus-producing) cells of the stomach and spreads to the lower sections of the stomach.  

 Chronic inflammation weakens the stomach lining, making it more susceptible to damage. Additionally, H. pylori can produce a specific protein called CagA, which can bind to stomach cells and trigger cell proliferation (abnormal cell growth), which could lead to the formation of tumours. 


Mucosa-associated lymphoid tissue (MALT) lymphoma 

MALT lymphoma is a slow-growing cancer that begins at the mucosal lining (MALT) of the gastrointestinal tract. MALT contains many lymphocytes, which are part of the lymphatic system that produces immune cells like your antibodies.  

H.pylori can produce a specific protein called CagA (cytotoxin-associated antigen), which can suppress the growth of lymphoid cells. This reduces the production of antibodies and other immune cells, hence the body is unable to kill off the bacteria or protect itself from other pathogens. 

 But how does this cause cancer? Usually, old or damaged cells have to die and get digested from the body. However, CagA protein inhibits the ability of lymphocytes to trigger apoptosis (cell death). Hence, abnormal B cells with mutations that can cause cancer will accumulate, eventually forming a tumour in the MALT which contains these mutated lymphocytes.   

The correlation between H. pylori infection and MALT lymphoma has been supported by various studies. They found that patients who received antibiotics also experienced a regression of MALT lymphoma. Since antibiotics target bacteria and not cancer cells directly, this trend shows that H. pylori plays a role in cancer growth.  

Luckily, MALT lymphoma is usually slow-growing and highly treatable.  


Colorectal cancer 

Colorectal cancer is the tumour growth along the colon lining (large intestines). H. pylori infection increases the secretion of gastrin, which is a hormone that triggers acid secretion in the stomach. Excessive gastrin can also stimulate the proliferation of rectal cells, increasing the risk of developing colorectal cancer.  


Risk Factors and Prevention

The main risk of H.pylori infection is a lack of good hygiene. Hence, always make sure to wash your hands after using the restrooms and ensure that your food and water sources are clean before consumption.  

With that said, having H. pylori infection does not mean you will get stomach cancer. Other factors such as smoking, having a family history of stomach cancer, or prior surgery for gastrointestinal conditions also increase the risk of developing gastric cancer.  

While genetic factors are out of our control, you can still take proactive steps to improve your lifestyle habits. Try to avoid smoking, excessive drinking, and processed foods that are high in salt as it could damage the stomach lining. Instead, opt for fresh fruits and vegetables which are known to strengthen the body’s protection against infection. Whole grains and nuts high in vitamin C and polyphenols are great for protecting the stomach lining and preventing bacteria colonisation.  

In addition to a good diet, consistent exercise also goes a long way in improving your muscular and cardiovascular health, which lowers the risk of cancer. Try to incorporate at least 30 minutes of exercise per day. It can be anything that gets your heart rate up: running, swimming, CrossFit, Zumba, and more! If you are busy or intimidated by the idea of exercising, start small: take a 10-minute walk per day. You can always increase the duration and intensity once you feel more comfortable.  


Treatment Options 

Getting treatment early reduces the likelihood of the infection turning to cancer. The treatment is typically a 2-pronged approach to eradicate the bacteria and allow the stomach to recover from the acid contamination: 

 Antibiotics. To prevent the bacteria from developing antibiotic resistance, two or more different antibiotics are prescribed.  

  • Proton pump inhibitors (PPI). Drugs such as omeprazole and lansoprazole prevent the stomach from producing acid. This mitigates the damage of gastric juice around the stomach tissues.   
  • Histamine blockers. Histamine is a hormone that triggers acid production. Similar to proton pump inhibitors, blocking histamine production reduces the acidity of gastric juices as well.  

 It is important to consult a doctor to determine which combination of treatment is best suited for your needs. You are typically required to test for H. pylori again 4 weeks after treatment.  



H. pylori is a common pathogen that can lead to various complications, including stomach cancer. Thankfully, with the availability of antibiotics and a good prognosis, most people recover quickly. 

Having H. pylori infection does not mean you will get cancer. Other factors such as exposure to carcinogens like cigarettes, poor diet, or genetic causes play a role as well.  

 No matter what condition you may have, the same rule applies: early diagnosis increases the chances of early recovery. If you experience any symptoms that could indicate a H. pylori infection, seek a professional immediately.  


Protect Your Health Today 

If you want to seek reassurance on your stomach condition, you can have a thorough discussion with Dr. Kum Cheng Kiong at the Centre for Screening and Surgery. Our clinic specializes incancer screening and treatment of cancersat an early stage with minimally invasive procedures. Call us to book an appointment today! 

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